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IntroductionWhen locating the different electronic parts in the semiconductor electronics area, voltage regulators are a critical component that is used to determine the reliability and efficacy of the power circuit. These are actually three essential components of the stable DC supply that will deliver the unchanged output voltage to provide the necessary power, even if it should encounter any changes in input voltage or load variations. This article delves into the intricacies of voltage regulators, focusing on the two primary types: linear [efficient, low-noise] and switching regulators [more compact, inefficient, noisy design]. It forms the fundamental part of the investigation by exposing the existing loopholes, the comparison between new and old approaches, the novel design, and the tips on the improvement aspects. Linear Voltage RegulatorsLinear Voltage regulators are straightforward, and the most common varieties are the ones that are applied in the widest range of circuits. They have resistance characteristics through emptying the excess voltage in the form of heat, which eventually generates the output voltage equal to or lower than what has to be expected. Sure, what also comes with widespread uses of linear regulators being simple to operate, accurate and long-lasting is the same strong demand for this kind of regulator. There are three fundamental components of a linear voltage regulator: the series are passed through as examples, for instance, bipolar junction transistor and field-effect transistor. Another feature is that the device has a feedback circuit that senses the output voltage and tweaks as necessary to keep the pass element measurement and levels reasonably stable. The linear regulators can give us the possibility to obtain very good output voltages that have low noise, and by this, their linearity is stable and load-regulated. The humble linear regulator is not without its shortcomings, a major one being its tendency to produce heat while changing current into voltage. One of the major issues that may have arisen in the circuit would have been the power dissipation. Consequently, a large heatsink would have been required to lower temperatures as a larger power consumption is needed, especially since the difference between the input and output voltages is great.Switching Voltage RegulatorsSwitching voltage regulators or SMPS (switch-mode power supply) are proven to be an alternative to linear regulators because of their efficiency and economy. The underlying technique used in these controllers to obtain a constant output is the use of the inductive and capacitive properties and the rapid turning off of the input voltage just after the controlled system starts. The regulators' switching output is much more efficient than linear regulators, which constitutes a big advantage for all, even more so reaching 90% efficiency in some cases. The so-called high-frequency factor does not differ from the classic factor in that the extra voltage is not converted to heat because, being on and off as needed, the transformation element gets switched "on". Even though the switch regulators have a broader range of input voltages and can deliver step-up and step-down conversion, resulting in a breakdown is a consequence of them being limited to a single switch frequency. However, a switching regulator is not simpler than a linear regulator, as the latter has fewer components. In contrast, a switching regulator needs such components as a switching transistor, an inductor, and a control circuit. These features can also lead to increased cost and signal integrity issues, e.g., pumping noise and electromagnetic interference (EMI). Comparison Between Linear and Switching RegulatorsVoltage regulators can be classified as linear and switching voltage regulators. They are categorized with their different features and trading to meet their various applications. Linear regulators are usually simpler, economical, and feature much less noise, but they are best for situations where low power and low noise circuitry are needed. Apart from those, they are better in efficiency compared to other converters when the input and output tension changes, as there is no power wasted because of the pass element. Nonetheless, a switching converter is a superior technology that allows for a wider variation of operating voltages and uses less energy. In some cases, by virtue of their low-temperature heat dissipation ability, they play a vital role in generating heat as a result of the source power disintegration, particularly when it comes to high-power devices as well as battery-powered devices. The cost-added convenience of the switching regulators is realized in operations where a large gap of voltages exists between the input and output; that is, the voltage drops when the power is stepped up or stepped down. Applications of Voltage RegulatorsVoltage regulators find a wide range of applications in the semiconductor electronics industry, including: Power Supplies:Voltage regulators are the core component of power supply units, and their standard operations are to keep the constant and level output voltage necessary for most of the electric tools. Microcontroller and Microprocessor Circuits:The regulators play the role of fine tuners, ensuring a clean supply voltage within the permissible range so that microcontrollers and microprocessors sensitive to voltage variation get the required voltage. Analog and Digital Circuits:Voltage regulators give life to the designed analog and digital circuits, which contain operational amplifiers, data converters and digital logic gates. Thus, their proper working is ensured. Automotive Electronics:The phenomenon is that the car's battery voltage is constantly preserved through the comprehensive protection circuit's regulator, around the nominal value level, subserving various electronic components. Portable Electronics:Energy supply units such as smartphones, laptops, and wearable devices are crucial for portability. Increasing the endurance of portable gadgets is strategic. Industrial and Medical Equipment:A great variety of components from different types of plants and clinical diagnostics system manufacturers make them an essential tool to ensure the success of such mission-critical tasks by keeping error-free and on-time running. Design Considerations for Voltage RegulatorsWhen designing voltage regulators, engineers must consider several important factors, including: Input and Output Voltage Ranges: Regulating the voltage is important in an electric power system as the input and output voltage variation in different units needs to be handled and well controlled by the regulator. Load Requirements:The regulator needs to maintain the required current and power output while keeping the voltage of the output between zero and 12V constant. Efficiency and Heat Dissipation:The concentrations of heat closed time and performance efficiency are to be very carefully fixed in the linear regulator so that it can work and subsequently have no thermal issues. Transient Response and Stability:This regulator shall be equipped to respond quickly to any changes in the load variations or output voltage values that form its task. Noise and EMI:Noise and electromagnetic interference (EMI) in the circuit should be correctly isolated and taken care of whenever possible; the regulator should be in such a way that it doesn't generate noise and EMI. Cost and Size: The device has to be a greener option, and the price should be bearable and apparent to the user so that it can fit in the space available for the application. Future Trends and Technologies in Voltage RegulationThe field is constantly developing and gives birth to new technologies and approaches that are directly related to the exploration of the semiconductor picture of high-speed transition requirements. Some of the key future trends and technologies in voltage regulation include:Wide-bandgap Semiconductors:The high-power and high-frequency applications are undoubtedly a domain for the adoption of wide-bandgap semiconductor materials: silicon carbide (SiC) and gallium nitride (GaN).Integrated Voltage Regulators: On-chip voltage regulators are being incorporated into SoC (System on a Chip) designs, which means the electronic systems are less bulky and more comprehensible.Advanced Control and Monitoring:Control algorithms for voltage regulation and tech enhancements of monitoring devices are in progress, and in the not-so-long term, more sophisticated and adaptive power management becomes possible.Wireless Power Transfer:Stand radios coupled with charging technology allow for limitless power intensities and flexibility in terms of remote charging, applicable to portable and wearable devices.Energy Harvesting and Storage:The combination of the voltage regulators together with the energy harvesting and storage systems (e.g., solar cells and batteries) creates the perfect conditions to make the systems autonomous and a lot more eco-friendly. ConclusionBetween the linear and the switching voltage regulators, a profound distinction needs to be created in addition to understanding their usage, which is essential for building electronic circuits that are both efficient and reliable. As the new high-tech grows more quickly and faster, it gives all the possibility that voltage regulators will be needed and will participate in the developed technology systems and complicated electronic devices. This is such a small overview, but the main issues associated with voltage regulations in the semiconductor electronics industry are mentioned in it. So, this overview is aimed at professionals and enthusiasts who want to know about the essence of the problem.

What is a LED?Video related to LEDLED Colours and materialsHow do LEDs work?Types of LedsCalculating LEDs resistor valueHow to Test LED LightsThe warning of LEDs useLEDs FAQWhat is a LED?LED = Light Emitting Diode. An LED must be prevented against transferring too much current because its electrical behavior differs significantly from that of a light. Typically, this is done by connecting a resistor in series with the LED. Never attach an LED directly to a power source or battery.LEDs must be wired in the proper direction; the diagram may be labeled with the letters an or + for the anode and k or - for the cathode (yes, it really is k, not c, for cathode). In the case of spherical LEDs, the cathode is the short lead and there may be a slight flat on the body. Although the cathode is the larger electrode within the LED if you can see it, this is not a recognized method of identification.LEDs Video related to LEDVideo Description: This video is mainly talk about how to design LED circuits, how to calculate resistor size, how to protect LED, how long will a battery power a circuit, how to calculate resistor power rating, how to connect LED and much more. LED Colours and materialsThe semiconductor material, not the coloring of the "package," determines the color of an LED (the plastic body). All colors of LEDs are available in uncolored, diffused (milky), or clear (commonly referred to as "water clear") packaging. The colored packaging is also offered in diffused (the typical type) and clear forms. White and blue LEDs could cost more than the other colors.ColorWavelength (nm)Voltage Drop (V)Semiconductor MaterialInfrared> 760< 1.9Gallium ArsenideInfrared> 760< 1.9Aluminium Gallium ArsenideRed610 - 7601.6 -2.0Aluminium Gallium ArsenideRed610 - 7601.6 -2.0Gallium Arsenide PhosphideRed610 - 7601.6 -2.0Aluminium Gallium Indium PhosphideRed610 - 7601.6 -2.0Gallium PhosphideOrange590 - 6102.0 -2.1Gallium Arsenide PhosphideOrange590 - 6102.0 -2.1Aluminium Gallium Indium PhosphideOrange590 - 6102.0 -2.1Gallium PhosphideYellow570 - 5902.1 -2.2Gallium Arsenide PhosphideYellow570 - 5902.1 -2.2Aluminium Gallium Indium PhosphideYellow570 - 5902.1 -2.2Gallium PhosphideGreen500 - 5701.9 -4.0Gallium Indium PhosphideGreen500 - 5701.9 -4.0Aluminium Gallium Indium PhosphideGreen500 - 5701.9 -4.0Aluminium Gallium PhosphideGreen500 - 5701.9 -4.0Indium Gallium NitrideBlue450 - 5002.5 -3.7Zinc SelenideBlue450 - 5002.5 -3.7Indium Gallium NitrideBlue450 - 5002.5 -3.7Silicon CarbideBlue450 - 5002.5 -3.7SiliconViolet400 - 4502.8 -4.0Indium gallium NitridePurplemultiple types2.4 -3.7Dual Blue/Red LEDsPurplemultiple types2.4 -3.7Blue with Red PhosphorPurplemultiple types2.4 -3.7White with Purple Plasticultraviolet< 4003.1 -4.4Diamondultraviolet< 4003.1 -4.4Boron Nitrideultraviolet< 4003.1 -4.4Aluminium Nitrideultraviolet< 4003.1 -4.4Aluminium Gallium Nitrideultraviolet< 4003.1 -4.4Aluminium gallium Indium NitridePinkmultiple types3.3Blue with phosphorPinkmultiple types3.3Yellow with Red, Orange or Pink phosporPinkmultiple types3.3White with Pink pigmentWhiteBroad spectrum3.5Blue/UV diode with Yellow Phosphor How do LEDs work?A P-type semiconductor (which has a higher hole concentration) and an N-type semiconductor are combined to create LEDs, which are semiconductor light sources (larger electron concentration). The P-N junction's electrons and holes will join once more when a strong enough forward voltage is applied, releasing energy in the form of light.LEDs (Light Emitting Diodes) transform electrical energy directly into light as opposed to conventional light sources, which first convert electrical energy into heat before turning it into light. This results in efficient light creation with minimal electricity waste.LEDs Emit Light Types of LedsDual In-Line Package (DIP) LEDs:The first LED chips were DIP ones, which are what most people think of when considering LED lights. Despite being more established than its more recent counterparts, DIP LED chips are still in use and are more frequently seen integrated into electronics because of their small size. However, they are not very strong and can only provide a small amount of brightness.DIP LEDs Surface Mounted Diode (SMD) LEDs:These are likely the most popular sort of LED chip available; they are installed and soldered onto the circuit board. They are more adaptable when it comes to encasing them within smaller electronics or across other forms of lighting, such as strip lighting, because they are brighter than their DIP counterparts and are also smaller. Three diodes can fit on a single SMD chip, allowing you to produce a variety of colors and provide customers more options. The LED market has undergone this significant progress. SMD 3528 and SMD 5050, both of which measure 5mm in width, are the two most used SMD chip sizes.SMD LEDs Chip on Board (COB) LEDs:The most recent advancement in LED technology is represented by these chips. Out of the three, COB LED chips are the brightest since they can frequently fit nine or more diodes onto a single chip. In what ways does this affect LED lighting? First off, it increases lighting efficiency by improving brightness-to-energy output. They can therefore be utilized with a variety of various lighting types. However, it's important to keep in mind that a COB LED chip's circuitry prevents it from emitting a wide variety of colors.COB LEDs Calculating LEDs resistor valueTo limit the current flowing through an LED, a resistor must be connected in series with the LED; otherwise, the LED will burn out fairly immediately. R, the resistor's value, is determined by:R = (VS - VL) / IR = resistor value in ohms (ohm).VS = supply voltage.VL = LED voltage (2V, or 4V for blue and white LEDs).I = LED current in amps (A) The LED current needs to be lower than what your LED is capable of handling. Since the The maximum current for typical 5mm diameter LEDs is frequently 20mA; however, many circuits can work with 10mA or 15mA. Divide the mA current by 1000 to convert it to amps (A) for the calculation.If the projected value is unavailable, pick the nearest larger standard resistor value so that the current will be a little less than what you chose. If you choose a higher resistor value to reduce the current, the LED will be less bright (for example, to extend the battery life).The color of the LED affects the voltage VL of the LED. The voltage of red LEDs is the lowest; yellow and green have a somewhat higher value. The highest voltages are used in blue and white LEDs. You can use 2V for red, yellow, and green LEDs and 4V for blue and white LEDs for the majority of applications where the precise value is not crucial. According to Ohm's law, the resistor's resistance, R = V/I, is determined by:V = voltage across the resistor (= VS - VL in this case) I = the current through the resistorSo R = (VS - VL) / IResistor Value How to Test LED LightsStep One: Use a MultimeterGet a digital multimeter with a diode reading capability. Simple multimeters only measure voltages, amps, and ohms. A multimeter with a diode setting is required to test LED lighting. Mid-range to high-range multimeters, which are more likely to offer this capability than affordable versions, can be found online or at your neighborhood hardware store.Multimeter Step Two: Connect the black and red test leadsTo the outlets on the front of the multimeter, attach the red and black test leads. The positive charge is in the red lead. The input marked "COM" should be connected in with the black lead, which is the negative.Multimeter Connect Step Three: Select the diode setting on the multimeter's dialTo move your multimeter's front dial from the "off" position, turn it clockwise. Up till you reach the diode setting, keep twisting it. The diode setting may be represented by the diode circuit symbol if it is not labeled explicitly. The cathode and the anode of a diode are both visually represented by the diode symbol. In this digital multimeter dial picture, we need to set the multimeter’s dial on 14 to test diode.Multimeter dial Step Four: The red probe should be connected to the anode and the black probe to the cathodeThe cathode end of the LED, which is typically the shorter prong, should be touched with the black probe. The red probe should then be pressed against the anode, which is the longer prong. Ensure that the black probe is connected before the red probe because doing so can result in inaccurate readings. During this test, be sure the cathode and anode are not in contact with one another since this could prevent electricity from flowing through the LED light and affect your results. Throughout the test, the red and black probes must not come into contact. After making the connections, the LED ought should turn on.Diode test Step Five: Verify the reading on the digital multimeter displayA healthy LED light should show a voltage of about 1600 mV when the probes are in contact with the cathode and anode. If during the test there is no reading displayed on your screen, repeat the procedure to ensure that the connections were completed correctly. This can indicate that the LED light isn't functioning if the test was done correctly. The transformer needs to be changed if your supply does not provide any output voltage. LED lights need to be replaced if there is voltage present at the output. The warning of LEDs useIn general, it is not a good idea to connect multiple LEDs in parallel with just one resistor shared between them. Only the lowest voltage LED will light if the other LEDs require slightly different voltages, and the higher current running through it could damage the other LEDs. One resistor can be used to successfully link identical LEDs in parallel, but since resistors are so inexpensive and the current utilized is the same as connecting the LEDs separately, this rarely provides any significant benefit.LEDs in parallelInstead, we should do as follows: Connecting LEDs in seriesConnecting LEDs in series LEDs FAQWhat can the LEDs be applied to?LEDs (Light Emitting Diodes) are mostly used to illuminate items and even spaces. Due to its small size, low energy consumption, long lifespan, and versatility in terms of use in many applications, it is applied everywhere. LED usage and applications include TV backlighting. How many types that LEDs own?Fundamentally, LED lighting uses three major forms of LED technology: DIP, SMD, and COB. What is LED and how it works?When an electric current passes through a semiconductor device called a light-emitting diode (LED), the LED emits light. When current flows through an LED, the electrons and holes recombine and produce light. How long do LED lights last?The longer lifespan of LED lighting fixtures is one of its main benefits. The most durable LED light fixtures have been evaluated to survive as long as 100,000 hours, whereas incandescent light bulbs were designed to last roughly 1,000 hours. On average, LED light bulbs last at least 20 years before needing to be replaced. Which is not a benefit of LED?On a capital cost basis, LEDs are now more expensive (price per lumen) than the majority of conventional lighting solutions.

Introduction RF power amplifier is an important part of various wireless transmitters. In the front-end circuit of the transmitter, the power of the RF signal generated by the modulation oscillator circuit is very small, and it needs to go through a series of amplification-buffer stage, intermediate amplification stage, and final power amplification stage to obtain enough RF power before feeding. In order to obtain a sufficiently large RF output power, a RF power amplifier must be used. RF Power Amplifier Design: The Basics Catalog Introduction Ⅰ Requirements of RF Power Amplifier Ⅱ Types of Power Amplifier in Use Ⅲ Parameters of RF Power Amplifier Design Ⅳ Key Feature: Non-Linearity 4.1 Nonlinear Characteristics 4.2 Influence of Nonlinear Characteristics Ⅴ FAQ Ⅰ Requirements of RF Power Amplifier With the vigorous development of modern digital mobile communication technology, users have more requirements on the performance of wireless communication equipment. To achieve stable and high-speed data transmission in various environments is one of the main goals of future mobile communication system researchers. The RF power amplifier is the last stage of the transmitter. It amplifies the modulated frequency band signal to the required power, ensuring that the receiver in the coverage area can receive a satisfactory signal level, but it cannot interfere too much with the communication of adjacent channels, and meanwhile try to keep the amplified high-power signal without distortion. The requirements of these different aspects make the users of power amplifiers have to consider many factors in all aspects. So you should get a full knowledge of RF power amplifiers. Figure 1. Classic RF Power Amplifier Circuit Ⅱ Types of Power Amplifier in Use What are the main types of RF amplifiers for such an important device?1) According to the operating frequency bandsAccording to the working frequency band, it can be divided into narrowband RF power amplifier and broadband RF power amplifier. The former generally uses frequency selective networks as load circuits, such as LC resonant circuits. The latter does not use the frequency selection network as the load loop, but employs the transmission line with a wide frequency response as the load.2) According to the network propertiesAccording to the nature of the matching network, power amplifiers can be divided into non-resonant power amplifiers and resonant power amplifiers. The matching network of the non-resonant power amplifier is a non-resonant system, such as high-frequency transformers, transmission line transformers and other non-resonant systems, and its load properties are purely resistive, where this is also called reactance properties.3) According to current conduction angleBased on it, RF power amplifiers can be divided into class A, AB, B, C, D, E and so on. The differences between these categories can be seen in the following table: Classification Conduction Angle Efficiency Linearity Application Class A Θ=360° ≤30% Very good Small Signal Low Power Amplification Class B Θ=180° ≤60% Lower than class A For High Power Class C Θ<180° About 60% Nonlinear amplifier For High Power Class AB 180°<Θ<360° 30%~60% Better than class B Small signal works in class A, large signal works in class B Class D Work in switch mode 80% Very good, only good for low frequencies Switch mode amplifier Class E Work in switch mode 90% Completely nonlinear amp Switch mode amplifier In the classification of amplifiers, we often talk about amplifiers of class A to E according to the conduction angle. Class A power amplifier is a linear amplifier, its response to the sine-wave  input is a sine-wave output, generally without distortion amplification, and the output frequency is the same as the input frequency. Since class A amplifiers do not require additional filtering circuitry, their packages can be small and cost less. The output of a class B amplifier is a half sine wave of the input, resulting in half-wave distortion, which produces many harmonics. The output power and efficiency of the class C working state are the highest among these working states, and most of the amplifiers used for radio frequency work in the class C. Figure 2. Class A Amplifier Load Curve   Ⅲ Parameters of RF Power Amplifier Design RF power amplifiers are electronic circuits that comprehensively consider issues such as output power, excitation level, power consumption, distortion, efficiency, size and weight. In the transmitting system, the output power of the RF power amplifier can be as small as mW and as large as several kW, but this refers to the output power of the final power amplifier. In order to achieve high power output, the last stage must have a sufficiently high excitation power level. At the same time, it has other important indicators, as follows:1) Operating FrequencyGenerally speaking, it refers to the linear operating frequency range of the amplifier. If the frequency starts at DC, the amplifier is considered to be a DC amplifier.2) GainThe working gain is the main indicator to measure the amplification ability of the amplifier. Here it is defined as the ratio of the power delivered to the load by the amplifier output port to the power actually delivered by the signal source to the amplifier input port.Gain flatness refers to the variation range of amplifier gain in the entire operating frequency band under a certain temperature, and is also a main indicator of the amplifier. Figure 3. Output Power and 1dB Compression Point (P1dB) Referring to the Figure 3, when the input power exceeds a certain amount, the gain of the transistor begins to decrease, and the end result is that the output power saturates. When the gain of the amplifier deviates from a constant or is 1dB lower than other small signal gains, this point is the famous 1dB compression point (P1dB). Generally speaking, the power capacity of an amplifier is expressed by the 1dB compression point.3) EfficientSince the power amplifier is a power component, it needs to consume the supply current. Therefore, the efficiency of the power amplifier is extremely important to the efficiency of the whole system. Power efficiency is the ratio of the RF output power of the amplifier to the DC power supplied to the transistors.ηp=RF Output Power/DC Input Power4) Intermodulation Distortion (IMD)Intermodulation distortion refers to the mixed components of two or more input signals with different frequencies passing through a power amplifier. This is due to the nonlinear nature of the amplifier. Among them, because the third-order intermodulation product is very close to the fundamental signal, it has the greatest influence, so the third-order intermodulation is the most important consideration for the related products. The lower the third-order intermodulation product, the better.5) Third-order Intermodulation Cut-off Point (IP3)The intersection point of the extension line of the fundamental wave signal output power and the extension line of the third-order intermodulation in Fig is called the third-order intermodulation cut-off point, which is represented by the symbol IP3. It is also an important indicator of nonlinearity. When the output power is constant, the greater the output power of the third-order intermodulation cut-off point, the better the linearity of the power amplifier.6) Dynamic RangeThe dynamic range of a power amplifier generally refers to the difference between the minimum detectable signal and the maximum input power in the linear operating region. Naturally, this value must be as large as possible.7) Harmonic DistortionWhen the input signal increases to a certain level, the power amplifier will generate a series of harmonics due to its work in the nonlinear region. For high-power amplifier systems, filters are generally required to reduce harmonics below 60dBc.8) Input/Output VSWR (Voltage Standing Wave Ratio)This is also a very important indicator of how well the amplifier matches the overall system. The deterioration of the input-output ratio will lead to the deterioration of the gain fluctuation and group delay of the system. However, it is difficult to design a power amplifier with a high VSWR. In general systems, the input VSWR of the power amplifier is required to be lower than 2:1.The main technical indicators of RF power amplifiers are output power and efficiency. Therefore how to improve them is the core of the design goals of RF power amplifiers. Usually in the RF power amplifier, the fundamental frequency or a certain harmonic can be selected by the LC resonant circuit to achieve distortion-free amplification. In addition to this, the harmonic components in the output should be as small as possible to avoid interference with other channels. Figure 4. Increase the Power of the RF Input Signal Ⅳ Key Feature: Non-Linearity In an ideal amplifier, the output signal should faithfully reflect the input signal, that is, the waveform should be the same. But in fact, for many reasons, the input signal cannot be exactly the same waveform as the input signal, which is called amplifier distortion.Amplifier distortion mainly includes frequency distortion (linear distortion) and waveform distortion (non-linear distortion). The former mainly refers to the difference in gain and delay of the amplifier for different frequency components; the latter refers to the same frequency, the output signal and the input signal are not linear. Frequency distortion is represented by spectral changes in the frequency domain, while nonlinear distortion is represented by changes in the time-domain waveform. Non-linear distortion is different from frequency distortion mainly because a large number of new frequency components are generated. The nonlinear distortion of the power amplifier is mainly discussed here. 4.1 Nonlinear Characteristics From the small-signal model and input characteristic curve of an ideal transistor, it can be seen that the transistor amplifier itself is not an ideal linear device, and at the same time, due to the influence of parasitic parameters, the linearity is further reduced. But within a certain power range, the transistor can be regarded as linear amplification. For power amplifier designers, how to obtain higher output power and improve linearity is the key.For a transistor amplifier, its volt-ampere characteristics can be described as follows: A power series expansion can be used to describe the volt-ampere characteristics of the device: In the formula, an(n=0,1,2,3,…) is a coefficient related to the circuit characteristics. Usually, the larger the n, the smaller the value of the coefficient an. When the nonlinear device in the circuit is represented by a power series, the number of series terms taken depends entirely on the magnitude of the signal amplitude and the required precision. 4.2 Influence of Nonlinear Characteristics The influence of the nonlinear characteristics of the device on the amplifier can be discussed in two cases. One is when there is only one signal at the input end, and the other is when the input end has one to two other signals in addition to the useful signal.🔺Only one signal at the inputLet the signal at the input end be , and substitute it into formula 2, at this time there is When the amplitude of the input signal is large and the effect of the cubic term must be considered, the fundamental frequency signal obtained from formula 2 is: Figure 5. 1dB Compression Point (PA) A3 in formula 3 is usually a negative value, that is, y1(t) decreases as the input signal amplitude increases, a phenomenon called gain compression.The "1dB compression point" is often used in engineering to measure the linear performance of the device. The 1dB compression point is defined as the input signal power P1dB that reduces the gain by 1dB from the linear gain. As shown in Figure 5. According to the definition of 1dB compression point and formula 3, we can get 🔺Two signals at the input.The signal amplified at the input end of the amplifier is generally not a single tone signal, but a spectral signal composed of a certain bandwidth. Due to the nonlinearity of the device, a large number of combined interference frequency components other than the useful signal will be generated at the output end. In addition, the combined frequency components of two or more interfering signals may also cause interference to the useful signal. Have an assumption: Substitute into formula 1, where It can be seen from the above formula that the fundamental frequency components of ω1 and ω2 are generated by the first and third power terms: A total of multiple frequency components are generated: ω1 , ω2 , ω1 ± ω2, 2ω1 - ω2, 2ω2 - ω1 , 3ω1 - 2ω2, 3ω2 - 2ω1.The difference frequency 2ω1 - ω2, 2ω2 - ω1 in the combined frequency is generated by the cubic term. The combination of these two signal frequencies is just within the sideband range of the signal frequency, which may cause interference to adjacent channels, and is one of the main indicators of transmission signal. Figure 6. Intermodulation Signal Interference This interference is caused by the mutual modulation of the two signals, so it is called intermodulation interference. At the same time, it is generated by a cubic term, so it is also called third-order intermodulation interference in engineering.When the third-order intermodulation interference is an important indicator of the communication machine, it is often measured by the intermodulation distortion ratio IMR and the third-order intermodulation blocking point IP3 in engineering. IMR is defined as the ratio of the amplitude of the third-order intermodulation product to the amplitude of the fundamental signal at a certain input amplitude. Definition of IP3: When the third-order intermodulation component increases to be equal to the fundamental frequency component, the receiver cannot receive normally, so there is a . Figure 7. Third-order Intermodulation Blocking Point 🔺Sideband Signals Figure 8. Sideband Signals and the Spectrum In fact, most of the sideband signals are generated outside the bandwidth after the useful signals of different frequencies within the bandwidth are modulated with each other. That is, the sideband signal rises faster than the in-band signal, and the spectral mask in the above figure becomes more and more flat. The increase of sideband signals will cause interference to adjacent channels, so the IEEE 802.11 protocol has strict requirements on the spectrum template, as shown in the Figure 9. Figure 9. DSSS Signal Modulation Spectral Mask Figure 10. OFDM 20MHz Bandwidth Signal Spectral Mask For the power amplifier, its nonlinear characteristics will increase the sideband of the modulated signal, and the sideband amplitude is not easily suppressed by other networks such as filters, and it is easy to cause design difficulties. Therefore, when choosing a PA, not only should pay attention to the maximum linear output that it can achieve, but also whether it can meet the sideband spectrum requirements at this output power.🔺Other Effects of NonlinearityIn addition to the previously mentioned gain drop, which generates a large number of harmonic components, as well as third-order intermodulation and sidebands, nonlinearity can also cause signal and EVM to deteriorate, etc.   Ⅴ FAQ 1. What is RF power amplifier?A radio frequency power amplifier (RF power amplifier) is a type of electronic amplifier that converts a low-power radio-frequency signal into a higher power signal. 2. How does RF power amplifier work?An RF amplifier is actually a tuned amplifier that enables the input signal of broadcast or transmitted information to control an output signal. The RF amplifier uses frequency-determining networks to convert the input signal into an output signal that will provide the required response at a given frequency. 3. What is the most efficient class of RF power amplifier?Class C AmplifierThe Class C Amplifier design has the greatest efficiency but the poorest linearity of the classes of amplifiers mentioned here. The previous classes, A, B and AB are considered linear amplifiers, as the output signals amplitude and phase are linearly related to the input signals amplitude and phase. 4. How do I choose an RF power amplifier?Considerations When Choosing An RF Power Amplifier:Gain.Operating Frequency.Output Power Level.Efficiency.Linearity.Mismatch Tolerance.Noise Level. 5. What are the advantages of RF amplifier?Following are the RF Amplifier advantages:The RF amplifier offers greater gain i.e. better sensitivity. It offers better selectivity and hence it has ability to select wanted signals from multiple input signals at the RF receiver. 6. What are the different types of RF amplifiers?Amplifier TypesBroadband AmplifiersGain Block AmplifiersLog AmplifiersVariable Gain AmplifiersLow Noise AmplifiersCoaxial and Waveguide Power AmplifiersLinear AmplifiersBi-Directional Amplifiers 7. What is RF amplifier circuit?A radio frequency power amplifier (RF power amplifier) is a type of electronic circuit that converts a low-power radio-frequency signal into a higher power signal. 8. Is Class D amplifier better than a class AB?The most common audio power amplifier operates in the Class-AB mode. It provides the greatest amount of output power with the least amount of distortion. ... Class-D amplifiers are switches that are more efficient and produce less heat than their Class-AB equivalents. 9. What are RF amplifiers used for?Whenever people need to magnify a radio frequency signal into a higher power signal, the RF amplifier plays a pivotal role. They are used in commercial and defense avionics, space and deep space, electronic warfare, naval applications, mobile internet, satellite communication, and wireless communications. 10. Which amplifier is used in RF amplifier?RF power amplifiers using LDMOS (laterally diffused MOSFET) are the most widely used power semiconductor devices in wireless telecommunication networks, particularly mobile networks. LDMOS-based RF power amplifiers are widely used in digital mobile networks such as 2G, 3G, and 4G.

Introduction Automotive connectors are a component that very common for electronic engineering technicians. Its function is very simple: it sets up a bridge of communication between the blocked or isolated circuits in the circuit, so that the current flows and the circuit realizes the predetermined function. The form and structure of automotive connectors are ever-changing. They are mainly composed of four basic structural components, namely: contacts, shells (depending on the types), insulators, and accessories. Common Automotive Electrical Connections Catalog Introduction Ⅰ Automotive Connectors Ⅱ Basic Structure Ⅲ Design Criteria Ⅳ Automotive Connector Development Trends Ⅴ Connector Selection Ⅵ Performance Standard for Automotive Electrical Connectors Ⅶ FAQ Ⅰ Automotive Connectors There are nearly 100 types of connectors used in general automobiles, and there are hundreds of connectors used in a single model. As people have higher and higher requirements for safety, environmental protection, comfort, and intelligence in automobiles, the application of automotive electronic products is increasing, which make the number of automotive connector applications increase. Figure 1. Automotive Connector Type Ⅱ Basic Structure The four basic structural components of automotive connectors, it is these four basic structural components that enable automotive connectors to act as a bridge to make cars run stably.First, the contact piece is the core part of the automobile connector to complete the electrical connection function. Generally, a contact pair is composed of a male contact piece and a female contact piece, because the electrical connection is completed by the insertion of two parts.The male contact is a rigid part, and its shape is cylindrical (round pin), square column (square pin) or flat (insert). The male contacts are generally made of brass and phosphor bronze. The female contact piece is the jack, which is the key part of the contact pair. It relies on the elastic structure to elastically deform when it is inserted into the pin to generate elastic force to form close contact with the male contact piece to complete the connection. There are many types of jack structures, including cylindrical type (split slot, necking), tuning fork type, cantilever beam type (longitudinal slotting), folding type (longitudinal slotting), box type (square jack) and hyperboloid wire spring jacks, etc.Second, the shell, is the outer cover of the automotive connector. It provides mechanical protection for the built-in insulating mounting plate and pins, and provides alignment when the plug and socket are inserted, thereby fixing the connector to the device.Third, insulators, are also often referred to as automobile connector bases or inserts. Its function is to arrange the contacts according to the required position and spacing, and to ensure the insulation performance with the shell. Good insulation resistance, withstand voltage performance and ease of processing are the basic requirements for selecting insulating materials to be processed into insulators.Fourth, accessories, are divided into the structural part and the installation part. Structural accessories such as retaining rings, positioning keys, positioning pins, guide pins, coupling rings, cable clamps, sealing rings, gaskets, etc. Mounting accessories such as screws, nuts, spring rings, etc. Most of the accessories have standard parts and general parts.   Ⅲ Design Criteria With the rapid development of the automobile industry, various functional parts and various components on the automobile are constantly developing in the direction of intelligence, refinement and reliability. The structural design, appearance design and material of automobile connectors are also proposed. higher requirement. Automotive connectors must meet the USCAR-20 standard, which is the performance standard of automotive electrical connector systems. It is necessary to stipulate that the electrical connector contact surface of automotive connectors should always be reliable throughout the service cycle, including the following factors:1) The material of the connector contacts is stable and reliable.2) Positive force stability.3) The voltage and current of the circuit are stable.4) The temperature requirements are within the specified range, including the surrounding temperature and its own temperature rise.5) Better robustness.6) It must be the same as the connector used for high-speed and long-distance communication computers, and the automotive connector must be able to work reliably under harsh conditions.7) Connector insertion force: below 20.5kg8) Connector retention force: 2.5kg or more9) Heat resistance: -40~120℃ Figure 2. Automotive Connectors Ⅳ Automotive Connector Development Trends The "Miniaturization", "High Speed" and "Intelligence" of connector products are the trends of future development. The future technological innovation of the industry is mainly concentrated in the following directions:1) Miniaturization DevelopmentThis technology is mainly developed for the miniaturization trend of connectors, and can be applied to micro-miniature connectors below 0.3mm, which belongs to the new varieties of MINI USB series products. It can be used for multi-contact expansion card slot connectors, which can meet and exceed the strict requirements of multi-contact surface mount technology butt joint coplanarity, with high accuracy and low cost.2) Wireless TransmissionThe high-frequency and high-speed wireless transmission of connector technology is mainly aimed at a variety of wireless device communication applications and has a wide range of applications.3) Simulation Application TechnologyIt is based on a variety of disciplines and theories, using computer and its corresponding software such as AutoCAD, Pro/E program stress analysis software as tools, through the establishment of product models and corresponding boundary conditions, to its mechanical, electrical, high-frequency simulation analysis and confirmation of other performances, thereby reducing the cost of product development failure caused by factors such as material selection and unreasonable structure, improving the development success rate, and helping to provide support for the realization of complex system applications for products.4) Connector Intelligence TechnologyThis technology is currently mainly used in DC series power connector products. Intelligent signal detection can be performed before power transmission to ensure that the positive and negative poles are turned on and the power is turned on after the plug is inserted in place. In the future, enterprises will need to develop similar intelligent technologies for other products because of the adverse consequences of arc damage and burn-in caused by conductive contact.5) Precision connector technologyPrecision connectors involve many aspects such as product design, process technology and quality control technology. The main technologies include the following aspects:a. Precision mold processing technology: Adopt CAD, CAM and other technologies, introduce high-precision processing equipment in the industry, and use personnel production experience and advanced equipment and technical means to achieve high-precision high-quality mold products.b. Precision stamping and injection molding technology: realize precise, efficient and stable all-round control and perfect surface quality of various stamping parts and injection molding parts to ensure product quality.c. Automated assembly technology: Through the application of precision control technology, semi-automatic testing machine technology, etc., the problem of manual operation of precision products is overcome and the core competitiveness is improved.6) Manufacturing Process ResearchThe competitiveness of products depends to a certain extent on the level of manufacturing technology. Continuously developing new manufacturing processes and improving existing production and processing technologies can greatly improve the manufacturing efficiency and quality assurance capabilities of products.a. Fine manufacturing process: This process is mainly aimed at technologies such as small spacing and thin thickness. Some companies have carried out research on the process of connectors with a spacing of less than 0.4mm. This type of technology can ensure that the company reaches the advanced level of the international industry in the field of ultra-fine manufacturing.b. Integrate development technology of light source signal and electromechanical structure. It can be applied to audio connectors placed in electronic components. By adding IC, LED and other electronic components to the audio connectors, which can also transmit analog signals and the function of digital signal. It breaks through the current design of audio connector conduction transmission in the form of mechanical contact.c. Low temperature and low pressure molding process technology. The sealing and physical and chemical properties of the hot-melt material are used to achieve the functions of insulation and temperature resistance. After packaging, the wire protects the welding point from being pulled by external forces, and the packaging of the DC connector body and the wire has a insulation, temperature resistance, impact resistance and other functions ensure product quality and reliability, and will continue to be developed and applied in different products in the future. Figure 3. Automotive Connectors Ⅴ Connector Selection 1) Electrical FactorCurrent requirements: high current, low current, signal level; Steady state, cyclic, transient.They determine the type of terminal/size of contact segment/plating (0.64mm to 8.0mm pin and male terminal).Wire diameter/insulation requirements: voltage drop and/or corrosion resistance, which determine the center distance of the connector.2) Location/EnvironmentTemperature: Engine compartment – sealed, ambient temperature >105℃; vibration, fluid compatibility, passenger compartment – unsealed, ambient temperature <85℃.Sealing: Potential for high pressure jet/splash, potential for immersion, humidity; fluid type, sealed or not for device connectors.3) StandardStandards: Customer StandardsInstitutional StandardsDomestic StandardsInternational StandardsConnector performance test requirements are included in system-level specifications. For GM, Ford and Chrysler are usually USCAR specifications, that is, engine-related applications have relatively high vibration requirements. Other OEMs generally have their own standards (similar to USCAR). What’s more, equipment-side suppliers are responsible for the performance of mating-side connectors.4) Customer PreferencePreferred product strategy: Reduce cost of connector systems with different methods:Ford: Design competition for door connectors.Ford: Prefer terminal design/supplier (focus on contact interface).General: Prefer the terminal design (focus on the hole position of the connector).Chrysler: Strategies for favoring terminal/plastic Part suppliers.5) Regional preferenceNorth America: USCAR Drawing/Performance/Design Criteria —Tangless Terminals, TPA, CPA regulations. In many instances the harness supplier has a significant influence.Europe: Design influence of contact contacts/development with major OEMs; preference for two-piece contacts, even if cost pressures and North American porting operations force OEMs to consider U.S technology, that is, accepting Tangled contacts. Long-term relationships between OEMs and suppliers.Asia: Traditionally influenced by Toyota. Focus on assembly ability (ergonomics) that affects quality assurance; North America influences China to change the status, like low-cost solutions.6) Physical factorsSize, number of circuits, mating position, wire harness docking or equipment connection, mechanical main features: levers, bolts; manual docking capability; multiple types of connectors for high input/output applications.7) AssemblyWire Harness: Insertion force of connectorVisual, audible and tactile operational feedback for users. Figure 4. Terminals & Connectors Ⅵ Performance Standard for Automotive Electrical Connectors For a connector, the specification parameters such as the ambient temperature, current carrying capacity, protection level, anti-vibration level, etc. will be defined in its specifications at the beginning of research and development, because when the connector is selected according to different requirements. The following are three most widely used standards USCAR-2-6, QC/T1067-2017 and GMW3191-2012.🔺QC/T-1067 Temperature Classification Class Ambient Operating Temperature Typical Installation Position A -40~85℃ Passenger compartment (Not recommended) B -40~100℃ Passenger compartment C -40~125℃ On engine D -40~150℃ On engine (hot locations) E -40~175℃ and above Negotiate   🔺QC/T-1067 Vibration Classification Class Typical Installation Position V1 On elastic parts of the body but not to the engine V2 On engine but not to heavily vibrating parts V3 Components subject to serve vibration V4 Components subject to extreme vibration V5 On Wheel   🔺QC/T-1067 Sealing Classification Class Description Typical Installation Position S1 Unsealed Passenger compartment or trunk S2 Sealed Exposed areas S3 Sealed (with high pressure spray) Exposed areas (with high pressure spray)   🔶GMW-3191 Temperature Class Class Ambient Operating Temperature Typical Installation Position 1 -40~85℃ Passenger compartment or trunk 2 -40~100℃ Underhood, chassis 3 -40~125℃ On engine, transmission 4 -40~150℃ On engine (hot locations) 5 Per connector CTS Per CTS GTS=Component Technical Specification   🔶GMW-3191 Vibration Class Class Typical Installation Position 1 On body or chassis 2 On engine 3 On wheel, Unsprung Mass 4 Severe applications (e.g., ECU, Throttle Body, EGR) 5 Transmission (internal and external) ECU=Engine Control Unit, EGR=Exhaust Gas Recirculation   🔶GMW-3191 Sealing Class Class Description Typical Installation Position 1 Unsealed Unsealed Passenger Compartment or trunk 2 Submersion Sealed Underhood or exposed areas, including door 3 High Pressure Spray Protected Exposed areas where high pressure spray is expected   🔻USCAR-2 Temperature Classification Class Ambient Operating Temperature Typical Application T1 -40~85℃ T1 is not recommended for new applications T2 -40~100℃ Typical suitable for use in passenger component T3 -40~125℃ Typical suitable for use in engine component T4 -40~150℃ Needed for some on-engine applications near hot components T5 -40~175℃ For use as needed   🔻USCAR-2 Vibration Classification Class Common Name Typical Application Other Requirements Met V1 Chassis Profile Components on sprung portions of vehiele not coupled to Engine None V2 Engine Profile Components coupled to Engine with no severe vibration possible Pass on V2 - pass also for V1 V3 Severe On-Engine Components subject to serve vibration Pass on V3 - pass also for V1 and V2 V4 Extreme Vibration Used as needed to correlate to extreme vibration areas Pass on V4 - pass also for V1 and V2 and V3 V5 Unsprung Component Wheel-mounted components None   🔻USCAR-2 Sealing Classification Seal Class Common Name Typical Application S1 Unsealed S1 is suitable for use in passenger components or other dry areas on a vehicle such as the trunk S2 Sealed S2 (meets requirements of 5.9.7) is for exposed locations S3 Sealed (with high pressure spray) S3 is for exposed locations. It meets Sections 5.9.7 plus 5.6.7; S3 is applications when robustness to direct splash is needed Regarding the vibration test, the main purpose is to check whether the performance of the connector system under the simulated actual vehicle vibration conditions meets the requirements. In the case of vibration or in shock, it will cause the coating wear of the terminal contact surface, the positive pressure attenuation, the failure of the mechanical system performance of the supporting plastic material, etc. Therefore, it is necessary to continuously monitor the contact resistance in the vibration experiment and ensure that it does not exceed 7Ω (or 1Ω) in the line for more than 1 microsecond. According to the definition and analysis of the connector using environment through the above different standards, it is necessary to understand that the use position, the temperature level, vibration level, and protection level should be considered to make the best choice.   Ⅶ FAQ 1. What are connectors in cars?Connectors used in automotive applications enable everything from stereo systems to drivetrains. As these systems become more connected, more automated, and more energy-efficient, they require connectors that can deliver high-speed connectivity in rugged, lightweight, and easy-to-install designs. 2. How do I choose a car connector?There are several criteria to consider when selecting electrical interconnect components, including:Current rating (current density)Connector size (circuit density)Engagement forceWire sizeConfiguration and circuit sizeOperating voltageAgency approvalsPrice per circuit 3. What are the different types of automotive electrical connectors?Automotive TerminalsContactsCrimp Wire Pins, Tabs & FerrulesFoil TerminalsInterconnect DevicesKnife DisconnectsMagnet Wire TerminalsPCB Terminals 4. How many connectors does a car have?Today, there are an average of 274 connectors in a vehicle. 5. Are all car stereo connectors the same?All aftermarket car stereos can use the same car stereo wiring harness, but it all depends on what the owner of the vehicle wants to do for one main reason. 6. What is uscar standard?SAE USCAR-2. May 1, 2004. PERFORMANCE STANDARD FOR AUTOMOTIVE ELECTRICAL CONNECTOR SYSTEMS. Procedures included within this specification are intended to cover performance testing at all phases of development, production, and field analysis of electrical terminals, connectors, and so on.

ⅠIntroductionAs electronic technology advances, there is a greater need for high-speed PCB design. Because they can work at high speeds with integrated circuits for most electronic devices, even simple ones. Some factors and parameters have to be considered when designing a high-speed PCB. Furthermore, you will discover that the fundamental PCB design rules and methods you have mastered are exactly what you need to learn. Needless to say, it will be extremely useful to PCB designers working on high-speed PCB designs.CatalogⅠIntroductionⅡ What is High-speed PCB Design?Ⅲ High-speed PCB Related VideoⅣ When Is a Printed Circuit Board Design Considered High Speed?Ⅴ High-speed PCB Design SkillsⅥ High speed PCB  Design ConsiderationsⅦ Setup for High-Speed DesignⅧ Floorplanning a High Speed PCBⅨ How to Tell If Your Project is High SpeedⅩFAQ Ⅱ What is High-speed PCB Design?High-speed PCB design is any design in which the physical characteristics of your PCB.  such as layout, packaging, interconnection, layer stack up, and so on, begin to impact the integrity of your signals. Furthermore, when you begin designing the boards and encounter issues such as delays, crosstalk, reflections, or emissions, you will enter the world of high-speed PCB design, Because of the attention paid to these issues, high-speed design is truly unique. You may be accustomed to designing a simple PCB  where you focus primarily on component placement and routing. However, it is more important to consider some factors when using a high-speed design, such as how close they are to signals, what width they will be, where you will place the traces, and what types of components they will be connected to. Furthermore, when the factors are considered, it will achieve a high level for your PCB design process.Figure1:What is High-speed PCB Design? Ⅲ High-speed PCB Related Video High-Speed PCB Design Tips - Phil's Lab #25 High-speed PCB Video Description: Quick overview of some general high-speed PCB design tips. Everything from stack-ups, controlled impedance traces, vias, and much more! Ⅳ When Is a Printed Circuit Board Design Considered High Speed?Certain characteristics can help you identify a high-speed  PCB design,  As a result, the design is fast if:It uses  HDMI , Ethernet,  SATA , PCI Express, USB, Thunderbolt, or other high-speed interfaces for fast data transfer; the circuit consists of several sub-circuits connected via high-speed interfaces (LVDS, DSI, CSI, SDIO,  DDR3 , etc.); the time of signal propagation over the track is at least 13 of the time of signal rise; the digital signal frequency is 50MHz or higher;Because the printed circuit board is so small, locating the components becomes a real challenge (especially when you come across a high-speed interface layout  ). Ⅴ High-speed PCB Design SkillsBe familiar with design software that provides advanced options.High-speed designs necessitate a plethora of complex features in your CAD software. Furthermore, there may not be many programs for hobbyists, and it rarely has advanced options based on Web suites. As a result, you must gain a better understanding of a powerful.High-speed routing  When it comes to high-speed traces.  a designer needs to understand the essential routing rules, such as not cutting ground planes and keeping trails short. As a result, keep digital lines a certain distance apart from crosstalk and shield any interference-creating elements from compromising signal integrity.Routing traces  with impedance controlImpedance matching is required for some types of signals with impedances ranging from 40 to 120 ohms. Antennae and a large number of differential pairs are examples of characteristic impedance matched hints.It is critical for designers to understand how to calculate trace width and layer stack for required impedance values. If the impedance values are incorrect, it can have a serious impact on the signal, resulting in data corruption. When creating a PCB  layout or a high-speed PCB  layout.  keep single-ended impedance Zo and differential impedance Zdiff in mind. Figure2: Parameters for Zdiff calculation Length matching traces  High-speed memory buses and interface buses have numerous lines. Because the lines can operate at high frequencies, it is critical that the signals travel from the transmitting terminal to the receiving terminal at the same time. Furthermore, it must have a feature known as length matching. As a result, most common standards define tolerance values that must match length.Figure3: High-speed PCB Design SkillsMinimizing loop areaHigh-frequency signals can cause  EMI  and EMC issues, so high-speed PCB  designers should be aware of these tips. As a result, they must follow basic rules such as having continuous ground planes, reducing loop areas by optimizing current return paths for traces.  and incorporating numerous stitching vias. Ⅵ High speed PCB  Design ConsiderationsThe importance of the PCB  layout cannot be overstated.PCB Design ConsiderationsSchematic considerationsTrace length tuningPCB materials and stack-up demands for high speedHigh-speed placement strategiesDifferential pair and trace length routing Crosstalk, impedance control, and parallelism considerationsUnderstanding stripline and microstripRouting topologies and best routing  practicesSimulators Ⅶ Setup for High-Speed DesignBefore the layout can begin, there are several design and database details that have to be addressed.SchematicWhile there is a lot to set up before you can start the layout of a high-speed design, most people don't give the schematic much thought. Designers need to check the parts, simulate the circuitry, and finish the design. Is the schematic, however, ready to be used for layout? If the designer cannot easily understand the intent of the circuitry, an unorganized schematic can make the PCB  layout difficult. High-speed signal paths, for example, must be laid out sequentially so that the designer can replicate component placement in the layout,  It's also a good idea to highlight parts of the design that you really understand.These include:Critical placement locations, as well as which side of the board certain parts may be required onKeep out zones should be established around critical components.High-speed routing data, such as topologies, measured lengths, and matched lengths.Information about a differential pair and controlled impedance. PCB LibrariesAs with any  PCB  layout.  the component footprints used for high-speed design must be checked and verified, but some additional library work may be required. Some footprints used in high-frequency or RF designs, for example, may require modifications to reduce pad sizes for signal integrity,  In addition, to accommodate high-density design requirements, some footprints may be reduced to their smallest size. However, component footprints should always adhere to industry and manufacturer specifications to the greatest extent possible to meet design for manufacturability (DFM) requirements. Many design tools, including Cadence's Allegro  PCB Editor, include online library browsing capabilities for importing vendor-specific footprint models. Materials and ComponentsBefore you begin the layout.  you must choose the materials that will be used to construct your high-speed circuit board. Harsh operating environments may necessitate a more robust board structure, and the physical properties of the materials will be required for calculated controlled impedance routing  :Consult with your manufacturer to determine whether your board will require high-speed materials.For high-speed and high-frequency applications, enhanced epoxy or PTFE materials may be a better choice.The dielectric constants of  FR-4  may be insufficient to hold the impedance values required, or the design may suffer from greater signal loss than is acceptable.The manufacturer will also need to review and confirm the PCB components. With today's supply chain issues, you'll want to make sure you have enough parts before committing to a design. Board Layer StackupSpecific board layer stack-ups are required for high-speed designs to aid in  EMI shielding and signal integrity,  The primary concern is to include a complete and continuous ground plane on an internal layer. Many boards will also have multiple ground plane layers spread across the board stack up to accommodate multiple layers of transmission line routing in microstrip or stripline configurations. The board layer stack-up must be created in the PCB CAD database or imported from another source. This is where the ability of PCB design systems to communicate directly with the vendor for stack-up information exchange, as demonstrated in the video above, can be extremely useful. Design RulesPCB design systems typically include a comprehensive set of design rules and constraints that can be applied to the design. Component and net classes will already be used in standard circuit board designs to specify spacing rules, trace widths, vias, and other constraints. With a high-speed design, a completely new set of rules should be established, including:Differential pairsSignal pathsRouting topologiesMeasured and matched trace lengthsTrace tuning parameters These rules can be set up for each design, or in many cases, imported from another layout to ease the designer’s workload. System ParametersThe parameters are the last but not least of the setups. Display parameters such as colors and fill patterns, grids, routing preferences, and a slew of others are among them. Designers can improve their tool efficiency by managing these parameters, Let's start laying out the board now that we've completed the high-speed design.Figure5: A PCB CAD system’s parameter setup menu for design colors Ⅷ Floorplanning a High Speed PCBIn a high-speed PCB layout  , there are no specific rules or standards for where components  should be placed. In general, the largest central processor IC  should be placed near the center of the board because it will typically need to interface with all other components  on the board in some way. Smaller integrated circuits (ICs) that connect directly to the central processor can be placed around the central IC  to keep routing between components  short and direct. Peripherals can then be added to the board to provide the necessary functionality.When the main controller IC  is near the center of the board, and other high-speed peripherals are placed around it, the high-speed layout works best. This is one of the reasons why motherboards have a large processor in the center of the board. The Altium Designer MiniPC project has its PCIe, DDR4, USB 3.0, and Ethernet peripherals arranged around the central FPGA SoC to facilitate routing.Figure6: high-speed PCB layoutOnce your components  are in place, you can use your design tools to begin routing your design. This is a critical aspect of high-speed board design because incorrect routing can compromise signal integrity. However, if the preceding steps were followed correctly, signal integrity is much easier to achieve. Set your impedance profile in your PCB design rules so that all routers in the design have the proper width, clearance, and spacing to maintain controlled impedance during routing. Ⅸ How to Tell If Your Project is High SpeedThere are a couple of schools of thought on this. The unfortunate reality is that there is no specific definition of what constitutes a high-speed PCB. It all comes down to a case-by-case assessment. As previously stated, if you're experiencing signal integrity issues on your PCB layout.  it's a good indication that you're working on a high-speed project.There's also the device-specific approach to consider. You'll be working on a high-speed project if you're designing a motherboard, cell phone board, or DSL router board. If you need to incorporate specific technologies into your layouts, such as HDMI, PCI Express, USB, or SATA, be aware that you will be dealing with high-speed design constraints.Figure7: Do you believe your design has a lot of traces? Take a look at this high-speed layout The final point to consider is whether you're working on a design with lumped or distributed circuits. What's the distinction? Designs with physical systems that are all small enough that they interact uniformly are referred to as lumped systems and are not fast. However, if your systems all operate independently within the confines of a larger whole, you have a distributed system and some high-speed design issues to deal with.Here is what you should remember:When the trace length becomes a significant fraction of the wavelength of the fastest signal, high-speed design considerations need to be considered.ⅩFAQ1. What is considered high speed design?High speed design specifically refers to systems that use high speed digital signals to pass data between components. The dividing line between a high speed digital design and a simple circuit board with slower digital protocols is blurry.2. What is high speed design Altium?High-Speed Design in Altium Designer. High-speed printed circuit board design is a process of balancing the circuit design requirements, device technologies, and fabrication materials and methodologies, to deliver a PCB that can transfer signals between the components, with integrity.3. What are high speed interfaces?High-Speed Serial Interface (HSSI) is a short-distance (50') communications interface that is used to interconnect routing and switching devices on slower local-area networks (LANs) with the higher-speed lines of a wide area network (WAN).4. What is high frequency PCB?High Frequency PCB is a type of PCB which is widely used in applications involving special signal transmission between objects. It is available in frequency range of 500MHz to 2GHz and is an ideal choice for mobile, microwave, radio frequency and high speed design applications.5. What is high speed signal in PCB?What is a high-speed signal in a PCB? Signals with frequencies ranging from 50 MHz to as high as 3 GHz are considered high-speed signals such as clock signals. Ideally, a clock signal is a square wave, but it is practically impossible to change its 'LOW' level to 'HIGH' level (and vice versa) instantly.

Introduction The transistor is a current-control device. For example, control the collector-emitter current by changing the base current. In a general voltage amplification occasion, this amplification effect comes from the use of resistors to convert current into voltage. In the small-signal model, the source of the base current is the ratio of the input voltage to the base-emitter dynamic resistance rbe, which is usually kΩ. So the base current is very small, and may only be a few tenths of mA. Through the amplification of the transistor, the base current is generated between the collector and the emitter by β times. This article will introduce how transistor works in the common-emitter amplifier circuit. Transistor Amplifiers Circuit Introduction Catalog Introduction Ⅰ Common-emitter Amplifier Circuit Formula Ⅱ Common-emitter Amplifier Circuit Design 2.1 Design Steps 2.2 Circuit Analysis 2.3 Common-emitter Circuit Design 2.4 Circuit Performance Parameters Ⅲ Common-emitter Amplifier Circuit Expansion 3.1 Increase Magnification 3.2 Low-voltage and Low-loss Circuit 3.3 Differential Output Circuit 3.4 Filter and Tuning Amplifier Circuit Ⅳ Summary Ⅴ FAQ Ⅰ Common-emitter Amplifier Circuit Formula Here, take the common emitter amplifier circuit as an example: Figure 1. Transistor Common-emitter Amplifier Circuit △Vo=VCC-△ieRc=VCC-β△ibRc=VCC-△Vi·Rc/rbe△Vi/rbe=△ibThus, the collector generates a current of β times ib:△ie=β△ibFurthermore, the output voltage can be obtained by the relative positive power supply potential:△Vo=VCC-△ieRc=VCC-β△ibRc=VCC-△Vi·Rc/rbeThus, we can get an inverted amplified voltage signal by AC coupling and controlling the collector resistance Re. But generally the emitter will have a resistance to control the gain, so the above formula is not practical. When designing a circuit in non-extreme situations, we often hope that the circuit can work with most general-purpose transistors, avoiding the parameter that depends on component parameters such as rbe. At the same time, it is very cumbersome to consider the base current in the specific calculation. Therefore, in the general design process, the existence of the base current is ignored in an approximate calculation (In some circuits, although the base current is ignored, it is still necessary to give the base a certain current drive to make the circuit working normally). In addition, the calculation of gain is the external circuit resistance not the rbe.Among them, the base-emitter tube voltage drop VBE is also a very important parameter, which is generally equal to 0.6V (silicon tube). The parameters of the transistor circuit can all be obtained according to VBE=0.6V and Ohm's law.The cumbersome part of the transistor circuit lies in the setting of the static operating point. Usually, careless design will cause clipping and distortion of the output waveform. Therefore, the selected values of some experimental values can be used for reference. The overall design idea is: quantitatively determine the voltage and current to calculate the resistance.   Ⅱ Common-emitter Amplifier Circuit Design The common-emitter amplifier circuit is a typical inverting amplifier, which has a wide range of applications and stable effects. First show the overall design ideas, and then explain the purpose and principles of the design in steps. 2.1 Design Steps 1) Determine the supply voltage VCC, and determine the static emitter current IE according to the frequency curve/noise curve/others.2) Determine VE, where selects 1~2V to absorb temperature drift.3) According to VE and IE, calculate the emitter static resistance RE ( IE≈IC).4) Determine the magnification Av, and apply the relationship Av=RC/RE to calculate the static collector resistance RC. At this point, the static working point has been established.5) Check whether the static operating point meets the requirements: positive output swing limit=VCC-IE·RC, negative output swing limit=IE·RC-VE. It is necessary to ensure that the amplified output voltage does not exceed the swing limit (usually the swing limit is larger). If RC is too large, there will be a downside clipping, so is the small RC. In addition, determine whether the power exceeds the limit: PC=VCE·IC.6) Determine the base bias voltage as follows: According to VBE=0.6V, it is easy to get VB=VE+0.6 (divide the voltage from the power supply through the resistor). Since ib is considered to be small and negligible, the current IB0 flowing through the base voltage divider resistors (R1, R2 in the above figure) should be much larger than ib. ib is approximately calculated as IC/β, and IB0 is about an order of magnitude larger than ib, so R2=VB/IB0, R1=(VCC-VR2)/IB0.7) Finally, determine the AC coupling capacitor value and the power supply decoupling capacitor value.Let's first use a designed common-emitter amplifier circuit to intuitively understand the waveforms of the next parts: Figure 2. Transistor Common Emitter Amplifier Circuit Design As shown in the figure, the circuit uses 2SC2240 tube, 15V power supply, and the input and output are AC coupled. The output signals are as following:  Figure 3. 4-channel Signal Waves The pale blue waveform is the input signal, selecting the sine wave of 1kHz, 1Vpp.The green is the output signal, amplified by about 5 times, and it is inverted.The blue is the base signal, which can be seen because the DC level is raised due to the influence of the base bias resistance.The red is the emitter signal, which is only a fixed value away from the base signal.   2.2 Circuit Analysis First, perform a DC analysis, that is, determine the static operating point. In the initial design process, the design and verification of static operating points are also the first to proceed. The static potential of the base can be easily calculated according to the base bias resistance, and the static potential of the emitter can be determined according to the voltage drop of the base-emitter tube as a constant. Therefore, according to the magnitude of the emitter resistance, the magnitude of the collector-emitter current can be obtained, and then the collector static potential can be obtained from the power supply voltage.Why is the static operating point important? Take the NPN transistor as an example, which is equivalent to two back-to-back diodes. If requiring the diode work, you must give it a proper bias to make it reasonably conductive. In the circuit, the base-collector diode prevents internal feedback, and the base-emitter diode is the key to achieving amplification. In other words, it is enough to design an external circuit so that the current flows normally in the base-emitter diode. This idea will be mentioned in the analysis of the carrying capacity of the emitter follower.Find the AC voltage gain. When the input voltage changes △vi, it will cause the emitter current to produce an AC change △ie. Since the base emitter voltage drop is constant, it does not contribute to the AC change, so △ie=vi/RE. Therefore, the emitter AC output voltage can be determined as vo=△ieRC=vi·RC/RE, and the AC gain is Av=RC/RE. This conclusion can quickly analyze the magnification of the common-emitter circuit.The output power rails are VCC and VE respectively, which are determined by the current characteristics of the transistor during operation, and there is generally no rail-to-rail output. According to the output power rail and the AC amplification factor, the circuit can be used.When the input and output are not AC coupled, the input (especially for DC) will cause the output waveform to be distorted.   2.3 Common-emitter Circuit Design After understanding the circuit characteristics, you can design the common emitter circuit according to the design steps at the beginning of this section. The static operating point and magnification have been determined during the analysis, and the other parts are designed below.Supply voltage: According to the swing of the output voltage, we can determine the size of the voltage. Usually the power supply voltage is larger than the output peak-to-peak value.Transistor: Select the appropriate transistor according to the operating frequency, required power, noise level and β, etc.Emitter current: Determine the size of the emitter current according to the frequency characteristics by consulting the device manual.RC and RE: Determined by the emitter voltage and current, and the magnification, pay attention to review the upper and lower limits of the swing and the rated power.Base bias resistance: VB is determined according to VE, thereby determining the voltage divider resistance of the power supply. Note that the current flowing through the voltage divider resistor should be one to two orders of magnitude higher than the base current. The base current is calculated by dividing the collector-emitter current by β.Coupling capacitor: The AC coupling capacitor is generally 10uF. Note that the coupling capacitor of the output stage and the input impedance of the next stage will form a high-pass filter. The cutoff frequency of the filter should be handled carefully.   2.4 Circuit Performance Parameters Through the method of AC analysis, we can obtain some characteristic parameters of the designed circuit, such as input and output impedance, magnification and so on.Input impedance: According to AC analysis, the input impedance is the parallel value of the base bias resistance. In small signal analysis, the base emitter dynamic resistance rbe should also be connected in parallel.Output impedance: The method to determine the output impedance is to add a load to the circuit. When the peak-to-peak output value drops to half of the no-load, the load impedance is the output value. Generally, the output impedance of the common-emitter amplifier circuit is the collector resistance RC.Magnification: Due to the influence of the base current, the actual magnification is about 10% lower than the design value. So the design formula is more practical.   Ⅲ Common-emitter Amplifier Circuit Expansion By improving the general common-emitter amplifier circuit, various application circuits with other characteristics can be obtained. This section introduces the means to increase the magnification, the low-voltage power supply circuit, the differential output circuit, and the tuning amplifier circuit. 3.1 Increase Magnification According to the introduction of the design circuit, the voltage gain is mainly determined by the ratio of the collector resistance RC to the emitter resistance RE. So it is common to change the ratio of the resistance to change the gain. However, the problem arises: these two resistors are responsible for determining the working current at the same time. Because the DC operating point is changed arbitrarily, the circuit is likely to be distorted or even not work.From another perspective, voltage gain belongs to the category of "AC Analysis", and the static operating point belongs to "DC Analysis". So add some reactive components to the circuit to change the ratio under the AC perspective, the resistance value during DC analysis does not change.This can be achieved by connecting the emitter resistor in parallel, or making the resistor in parallel with the capacitor, that is, modifying the circuit in the first section: Figure 4. Common-emitter Amplifier Circuit Pay attention to the emitter in the above figure. In the AC analysis, the resistor R4 is short-circuited by the capacitor. At this time, it is equivalently considered that the emitter resistor is only R7 (330Ω). From the signal source and the oscilloscope, the signal has been amplified nearly 50 times at this time. It is much larger than the original design value (10k/2k=5), thus realizing the expansion of voltage gain. If the original emitter resistance is not split, but the entire capacitor is connected in parallel, the maximum gain βRC/rbe will be obtained at this time.How to choose the capacitance value? It should be noted that after the capacitors are connected in parallel, the entire circuit will have high-pass characteristics, and the cut-off frequency is f=1/2πRC. If this high-pass characteristic is not required, the C capacitance value can be selected to a larger value between 47uF~100uF.In addition, the capacitor C6 has the function of temperature compensation. 3.2 Low-voltage and Low-loss Circuit If the op amp circuit is powered by a dry battery (1.5V), it is not realistic, but the transistor circuit can be done. The key is to use the conduction voltage drop of the external diode to offset the base-emitter voltage and have small small. The circuit in the figure below can still amplify small signals as designed even under 1.5V power supply: Figure 5. Common-emitter Amplifier Circuit But the disadvantage is that the maximum voltage of the system is always below the supply voltage. Because of the small circuit loss, it is suitable for low power consumption. 3.3 Differential Output Circuit Fully differential op amps can provide dual-mode output, and many transmission lines also require differential transmission. Transistor circuits can also perform differential output. In addition to the principle of a common emitter amplifier circuit, the principle of an emitter follower is also used. The following figure shows the circuit connection of the differential output. Figure 6. Common-emitter Amplifier Circuit It can be seen that two differential signals with the same shape and opposite phase are output. The collector signal is in phase with the input signal, and the emitter output signal is in phase with the input signal. However, the output impedance of the two signals is different due to the different lead-out positions. The output impedance of the inverted output is higher (RC), and the output impedance of the non-inverted output is lower, which is suitable for driving the load. The inverted output is generally connected to the emitter follower before driving.In addition, the static potential of the base should be set between VCC and GND as much as possible to expand the undistorted output range.   3.4 Filter and Tuning Amplifier Circuit The introduction of reactive components in the circuit will cause the properties of the circuit to change with the frequency. We can use this property to design LPF, HPF, and tuning amplifier commonly used in high-frequency circuits. Actually, it uses the characteristic that the impedance of the reactance element changes with the frequency, and then changes the voltage gain at the current frequency. The impedance at the resonance frequency is often purely resistive and has an extreme value to achieve frequency selective amplification. The following show low-pass, high-pass and frequency selective amplifiers at specific frequencies:① LPF Figure 7. Common-emitter Amplifier Circuit As shown in the figure, a low-pass filter is constructed (the input of the bode tester is placed at the base instead of the output of the signal generator, because the input coupling capacitor will form a high-pass filter with the input resistor, which affects the observation effect), and its cut-off frequency is about 1.06kHz, calculated by f=1/2πRcC.From the sinusoidal steady-state analysis, the impedance of the RC parallel loop is R/√(1+(wRC)^2). As the frequency increases, the impedance decreases, so the voltage gain decreases, forming a low-pass characteristic.② HPF Figure 8. Common-emitter Amplifier Circuit As shown in the figure, a high-pass filter is constructed, and the calculation of its cut-off frequency is similar to that of LPF.At the gain peak point, the voltage gain reaches 50dB, which is close to the β value of the transistor. Then the gain is attenuated due to the deterioration of the transistor's frequency characteristics.③ 10.7MHz Figure 9. Common-emitter Amplifier Circuit By replacing RC with an LC network with a resonance frequency of 10.7MHz, a frequency selective amplifier can be obtained. As shown in the figure, the amplification factor is 35dB at 10.7M, while the amplification factor when detuning 1MHz is only 12.6dB. The disadvantage is that the pass-band is slightly wider, the rectangular coefficient is not good enough, and the equivalent quality factor of the loop is about 65.2, which is relatively large. In addition, the high-frequency decoupling capacitor has been changed to 1uF. Resonant Amplifier Circuit Example: Figure 10. Resonant Amplifier Circuit Example   Ⅳ Summary Transistor amplifier circuit is the basis of an operational amplifier circuit, and common-emitter configuration is the most commonly used form. Drawing lessons from the feature that the amplifier's magnification can be easily determined by the ratio of two resistors, and the gain of the common emitter amplifier can also be approximated by the ratio of the two resistors.   Ⅴ FAQ 1. What are transistor amplifiers used for?Amplifiers are derived from the transistors because they are capable of operating under three regions active, cut-off and saturation. For the purpose of amplification, the focus will be on the active region. The main purpose of these amplifiers is to enhance the strength of the applied input signal without alteration. 2. How does a transistor amplify current?Transistors are normally used as amplifiers. ... The small current travels from the voltage source into the base of the transistor. A current at the base turns on the transistor. The current is then amplified and travels from the emitter of the transistor to the collector. 3. What is a common emitter transistor amplifier?The common emitter amplifier is a three basic single-stage bipolar junction transistor and is used as a voltage amplifier. The input of this amplifier is taken from the base terminal, the output is collected from the collector terminal and the emitter terminal is common for both the terminals. 4. Why common emitter is used in amplifier?Common emitter (CE) configuration. ... Common emitter transistors are used most widely, because a common emitter transistor amplifier provides high current gain, high voltage gain and high power gain. This type of transistor gives for a small change in input there is small change in output. 5. What is the use of CE amplifier?In electronics, a common-emitter amplifier is one of three basic single-stage bipolar-junction-transistor (BJT) amplifier topologies, typically used as a voltage amplifier. It offers high current gain (typically 200), medium input resistance and a high output resistance. 6. How does transistor work as amplifier?A transistor acts as an amplifier by raising the strength of a weak signal. The DC bias voltage applied to the emitter base junction, makes it remain in forward biased condition. ... Thus a small input voltage results in a large output voltage, which shows that the transistor works as an amplifier. 7. What is common emitter amplifier circuit?The Common Emitter Amplifier circuit has a resistor in its Collector circuit. The current flowing through this resistor produces the voltage output of the amplifier. ... The Base of the transistor used in a common emitter amplifier is biased using two resistors as a potential divider network. 8. What are the main parts of a transistor amplifier circuit?A Single stage transistor amplifier has one transistor, bias circuit and other auxiliary components. The following circuit diagram shows how a single stage transistor amplifier looks like. When a weak input signal is given to the base of the transistor as shown in the figure, a small amount of base current flows. 9. What is the phase difference in common emitter amplifier?The phase difference between the input and output voltage of CE amplifier circuit is. The phase difference of 1800 between the signal voltage and output voltage in a common emitter amplifier is known as phase reversal. 10. When an NPN transistor is used as an amplifier?For a npn transistor to be used as an amplifier, forward bias has to be applied on the transistor. Thus, when an npn transistor is used as an amplifier, holes move from base to emitter. So, the correct answer is option D i.e. holes move from base to emitter. 11. When an NPN junction transistor is used as an amplifier in CE mode?A transistor is used in the common emitter mode as an amplifier then: (A) the base emitter junction is forward baised. (B) the base emitter junction is reverse baised. (C) the input signal is connected in series with the voltage applied to bias the base emitter junction. 12. How is an NPN transistor used as an amplifier show with its circuit diagram?The circuit of a common-emitter amplifier using an n-p-n transistor is shown below : In a common emitter amplifier circuit, the input signal voltage and output collector voltage are in opposite phase. i.e 180° out of phase. Thus the phase difference between the input signal and output voltage is 180°. 13. How does a common emitter amplifier work?Operation of Common Emitter AmplifierWhen a signal is applied across the emitter-base junction, the forward bias across this junction increases during the upper half cycle. This leads to an increase in the flow of electrons from the emitter to a collector through the base, hence increases the collector current. 14. What is β for a CE configuration?Base Current Amplification Factor (β)The base current amplification factor is defined as the ratio of the output and input current in a common emitter configuration. In common emitter amplification, the output current is the collector current IC, and the input current is the base current IB. 15. What is current gain CE configuration?The current gain of a transistor in CE configuration is defined as the ratio of output current or collector current (IC) to the input current or base current (IB). The current gain of a transistor in CE configuration is high. Therefore, the transistor in CE configuration is used for amplifying the current.