ic Related Articles

The laminate substrates, one of the most widely used carriers in RF module packaging. This method that combines the traditional laminate substrates technology with the integrated passive device technology (IPD) is a win-win solution that can achieve the best balance in cost, size, performance, and flexibility. The application of laminate substrates with IPD devices is discussed with two examples in this article.     Catalog I. General Introduction II. Comparison of IPD and SMD(Surface Mounted Devices) and LTCC Discrete   Device Circuits III. Application Examples IV. Conclusion FAQ   I. General Introduction   A wide range of packaging carrier technologies are available in radio frequency packages(hereinafter referred to as RF) and wireless products, including lead frames, laminate substrates, low-temperature co-fired ceramic (hereinafter referred to as LTCC), and silicon backplane. Because the increasing function has higher requirements for integration, also more demands put forward for the system-level packaging method (SiP). Lead frame substrate packaging technology has been greatly developed in the past few years, including etching inductors, adding passive devices to pins, stacking technology of chips, and so on. Frame substrates are the cheapest cost option, but higher functionality requires more wiring and more vertical space utilized, therefore framework package is rarely used in RF integration solutions.   LTCC has been proven to be a high-performance substrate material that provides high integration due to its multi-layer structure, the high dielectric is constant, and high-quality factor inductance. The passive device can be embedded in LTCC, such as independent RCL or functional blocks containing RCL, so that SMT(surface mounted technology) devices require minimal planar space and improved electrical performance.   Integration is the advantage of LTCC, however, warping, cracks, secondary reliability of substrate, and the whole supply chain structure (transfer of substrate during packaging) limit the LTCC, which makes it impossible to become a popular carrier substrate selection.   Silicon substrate carriers, such as the chip-scale module package(CSMP) of STATS ChipPAC, have been widely used in wireless solutions requiring high integration, excellent electrical performance, and small profile coefficients. CSMP is an ideal packaging form of a fully integrated solution that can include RFIC and baseband IC. However, such integration is not the lowest cost and is not required for all RF and wireless devices.   The above-mentioned reasons lead us to think of the laminate substrates, one of the most widely used carriers in RF module packaging. This method that combines the traditional laminate substrates technology with the integrated passive device technology (IPD) is a win-win solution that can achieve the best balance in cost, size, performance, and flexibility. The application of laminate substrates with IPD devices is discussed with two examples in this article.     II. Comparison of IPD and SMD(Surface Mounted Devices) and LTCC Discrete Device Circuits   RF modules need independent RCL or combined RCLs to implement functional blocks such as filters, diplexer, balun, which are usually the SMD or IPD.   The traditional laminate substrate is not suitable for embedded passive devices, and high dielectric material lamination is limited by large cost. Spiral inductors can be designed inside the laminate substrate, but the inductance is limited. Therefore, laminate substrates are more likely to combine SMT with IPD, which has the advantages of cost, shape size, performance, and so on.   It needs to trade-off when SMDs be used and when specific passive devices are designed into reasonable IPDs. For example, when a capacitor larger than 100.0pF is required, the use of SMT devices has the advantage of size and cost.   In addition, SMT passive devices are generally recommended when a small number of decoupling capacitors or independent inductors and resistors are required in the design. The surface mount device can make full use of the Z direction of the occupied space while the IPD mainly uses the XY direction, the latter has very limited utilization of the Z height direction.   Thus it is wise to use SMT devices when the surface area of the IPD devices exceeds the available space. In order to find the best balance between IPD and SMT devices, a curve describing the relationship between the device value and the area required by IPD is developed (Fig. 1) for design reference.   Fig.1 Inductance and Capacitance of IPD fabricated on Silicon substrate Using silicon-based IPD technology, an 0201 SMD device (0.15mm2) can generate a 25.0nH inductance value or 50.0pF capacitance value. In other words, If the capacity is smaller than these two values, the external dimensions of the devices/circuits scheme are smaller than that of 0201 devices.   IPD schemes are suitable for functional blocks for a variety of reasons. First, although the silicon-based IPD inductor also uses a spiral form, it can use smaller linewidth and isolation space. In addition, high-resistive silicon substrates are allowed to produce higher-quality inductors.   As a result, the mass and shape coefficients of an IPD inductor are comparable to those of SMD devices. Second, small-capacity capacitors (in RF applications) are easier to build in IPD. Finally, comparing with connecting SMD devices with PCB, or internal connections to LTCC, the interconnect paths on silicon substrates are shorter.   For an ultra-wideband (UWB) application filter, as an example, the existing LTCC filter size is 3.2mm × 2.5mm × 0.8mm, and if the same layout is used in IPD, the size will be 1.6mm × 1.0mm × 0.5mm (Figure 2). IPD filter has a thinner shape and its size has been reduced by five times. Fig.2 Size Comparison between LTCC Filter and IPD Filter Comparing with other cases, for filters (such as LPF or BPF), IPD can get five times smaller shapes; for unbalanced transformers, using IPD shape can be two times smaller.   Another way is to use embedded inductors (inside laminates) and SMT capacitors to make filters, but in this way means occupying more space than LTCC or IPD, also including performance limitations.   In addition, since the process of assembling a whole integrated functional block is split into two parts (PCB inductor and SMT capacitor), the package requirements must be stricter for the assembly processes.   SMT devices have different sizes. In the RF module application, the most commonly used is 0201. Smaller 01005 devices have just appeared, but they are usually more expensive and have limited device value.   These SMT devices are usually attached to the laminate using a high-speed mounting machine, which is then soldered back to the laminate.   Fig. 3 An IPD are Bonded on A Laminated Substrate or Upside Down on It in an RF Module The IPD can be in the form of a bare chip or a convex device and then welded to the substrate by wire bonding or inversion (Fig. 3). The convex IPD chip and SMT device can be pasted by a high-speed mounting machine. After finished, the other chips can be directly placed on the substrate by wire bonding.   III. Application Examples   Example 1—GSM Matching Circuit In an RF receiver, matching circuits are needed to improve the performance of PA and LNA active circuits. These matching circuits include RCL devices. Considering cost and performance, these RCL devices can be removed from the chip and implemented in the form of SMD or IPD.   We compare a client's GSM transport module with an out-of-chip adaptor. In this module, there are 73 passive devices for matching circuits and DC decoupling. If only SMD elements are used (assuming all devices can be 0201), the package size will be 11mm × 11mm. However, if some devices are implemented in the form of IPD, the size of the module can be significantly reduced (Table 1).   Table.1 Package Size Comparsion between SMD and IPD+SMD IPD is very suitable for the low frequency (860MHz) and high frequency (1800MHz) adapters of GSM. In addition to some large capacity decoupling capacitors, 55 RCLs can be made in a smaller IPD network, which the package size can be only 7mm × 7 mm. In order to simplify, the complexity of routing is not taken into account in all examples.   It should be noted that the IPD network is treated as an integrated chip because its shape coefficient and thickness are similar to that of an integrated circuit.   IPD network is stacked with the transport chip, although it increases the thickness of the module, the IPD thickness is only 0.25mm, thus there is no obvious effect on the thickness increase (although it increases the thickness of the module when the IPD network stacked with the transport chip, there is no obvious effect on the thickness as the IPD thickness is only 0.25mm).   Therefore, the IPD packaging stack saves space and can be stacked on top or bottom of another chip by wire bonding or flip-chip bonding.   Example 2—GSM Balun Circuits In order to suppress the noise and improve the PA performance, differential output settings are often used for PA, thus a transformer is needed to convert the single-step terminal to the differential one. However, transformers that can be supplied by the industry have a fixed impedance transformer ratio, such as 50.0~100. 0 Ω transformers or 50.0~200. 0 Ω transformers.   Most PAs have low output impedance to transmit high power, which requires a matching circuit between the transformer and PA, as shown in figure 5 (b). In this example, the output matching circuit and transformer function block of PA are used to demonstrate the effects of IPD technology.   Fig.4 Package Comparison of Two Schemes There are GSM low frequency (860 MHz) and high frequency (1800 MHz) circuits in the application. Different frequencies have different matching circuits and transformers to convert a differential-terminal output to a single-step output (50.0Ω). In the existing form of the product, a customer uses a standard chip LTCC transformer with dimensions of 2.0 mm * 1.25 mm * 0.95 mm and 1.6 mm * 0.8 mm * 0.8 mm * 0. 6 mm.   Because the standard transformer has 50.0Ωto 200.0Ωimpedance conversion and does not match the specific power amplifier output impedance, the module needs to be independent with a 4RCL device. The current LTCC + SMD solutions are shown in Table 2.   Table.2 Size Comparsion between IPD and LTCC + SMD     Because an IPD transformer can be designed to match any amplifier output impedance, there is no need to use a separate matching circuit (4 RCL) to each frequency band. In other words, the matching function can be embedded into the Balun transformer.   The overall size of the IPD scheme is 2.5 mm2, which is about four times smaller than the size of the existing LTCC+SMD scheme. In addition, the matchers and transformer circuits are only about 0.25mm high, which is also thinner than discrete LTCC devices.   Fig.5 (a) IPD Balun in the high and low frequency band of GSM, the sizes are 1.5mm*1.0mm and 1.0mm * 1.0mm, and Matching function has been embedded in Balun transformer. Figure 5 (b) The function-block solution of output matching circuit and transformer. IPD solution eliminates the use of SMD devices completely in matchers and transformer modules. It not only reduces the area by four times but also greatly cuts the cost of the packaging process. Because it is integrated into an IPD module instead of using a LTCC separator, balun transformer, and four RCLs, the effects of yield and process changes are improved.   IV. Conclusion     There have been many studies on the ideal solution of RF packaging in recent years, and the most important thing is to strike a balance between cost, volume, and performance. Although remarkable progress has been made in the lead frame technology, the performance of the LTCC substrate has been improved. The technology of IPD integration and laminate substrates is still the best considerate solution.   Laminate substrates have low cost, high flexibility, mature supply chains, and fast manufacturing cycles. IPD can produce excellent RF functional blocks and can be mounted on laminate substrates as easily as chips or SMT devices. Combining laminate substrates with IPD provides a very broad range of RF solutions. The two GSM examples studied in this article are just illustrating the typical size reduction. This technology can also be used in RF circuits of mobile TV, GPS, WLAN, and WiMax devices.     FAQ   1. What is RF and how it works? Radio frequency waves (RF) are generated when an alternating current goes through a conductive material. ... Frequency is measured in hertz (or cycles per second) and wavelength is measured in meters (or centimeters). Radio waves are electromagnetic waves and they travel at the speed of light in free space.   2. How do RF modules transmit data? An RF transmitter receives serial data and transmits it wirelessly through RF through its antenna connected at pin4. The transmission occurs at the rate of 1Kbps - 10Kbps. The transmitted data is received by an RF receiver operating at the same frequency as that of the transmitter.   3. How does RF transceiver work? RF transceiver module is used in a particular device where both the transmitter and receiver houses in a single module. Such devices transmit and receives RF signal, so that is named as RF Transceiver. ... The transmitter and Receiver parts in the RF transceivers called as RF Up converter and RF Down converter.   4.What is RF transmitter and receiver? RF signals travel in the transmitter and receiver even when there is an obstruction. It operates at a specific frequency of 433MHz. RF transmitter receives serial data and transmits to the receiver through an antenna which is connected to the 4th pin of the transmitter.   5. Is RF dangerous? RF radiation has lower energy than some other types of non-ionizing radiation, like visible light and infrared, but it has higher energy than extremely low-frequency (ELF) radiation. If RF radiation is absorbed by the body in large enough amounts, it can produce heat. This can lead to burns and body tissue damage.   6. Why is RF used? RF energy in more specific applications, like in the medical field, have equally specified purposes. MRI (Magnetic Resonance Imaging) uses RF waves to generate images of the human body. RF is also used to destroy cancer cells and perform cosmetic treatments that tighten skin, reduce fat, or promote skin cell healing.   7. Is WIFI a RF? Very basically, Wi-Fi is made up of stations that transmit and receive data. Wireless transmissions are made up of radio frequency signals, or RF signals, which travel using a variety of movement behaviors (also called propagation behaviors).   8. How is RF signal transmitted? As the RF waves move away from the transmitting antenna they move towards another antenna attached to the receiver, which is the final component in the wireless medium. The receiver takes the signal that it received from the antenna and translates the modulated signals and passes them on to be processed.   9. What devices use RF? Modern devices often generate electromagnetic fields of radio frequency (RF) ranging from 100 kHz to 300 GHz. Key sources of RF fields include mobile phones, cordless phones, local wireless networks and radio transmission towers. They are also used by medical scanners, radar systems and microwave ovens.   10.How far can RF travel? The distance a radio wave travels in a vacuum, in one second, is 299,792,458 meters (983,571,056 ft), which is the wavelength of a 1 hertz radio signal. A 1 megahertz radio wave (mid-AM band) has a wavelength of 299.79 meters (983.6 ft).   11. What RF sensing? Unlike traditional hardware sensors, RF sensing provides users with low-cost and unobtrusive services. Fur- thermore, due to the broadcast nature of RF sig- nals, RF sensing can be used not only to monitor multiple subjects, but also to capture changes in the environment over a large area.   12. What is the frequency range of RF? Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz.   13. How do you calculate RF? The Rf value of a compound is equal to the distance traveled by the compound divided by the distance traveled by the solvent front (both measured from the origin).   14. How do I connect RF headphones to my TV? On the back of the headphone transmitter, connect the other end of the audio cable to the AUDIO IN jack. Connect the AC adapter into the transmitter's DC IN 9V jack and then plug it into a wall outlet. Adjust the TV volume to the desired level. Turn on the wireless headphones and adjust the volume to the desired level.   15. What is the difference between RF and IR? RF (radio frequency) technology uses radio waves to transmit the audio signal. These are susceptible to RF interference. IR (infrared) technology uses infrared light to carry the audio signal thus keeping the signal in the room and eliminating RF interference.   You May Also Like How Does RFID Make An Impact On Retail Industry Basic Introduction and Future Development Trend Analysis of RFID Technology Powercast Announced The Industry’s First RFID Sensor Tags Which Can Include Multiple Sensors in A Single Tag

  In daily production and life, ultrasonic ranging sensors are mainly used for non-contact automatic parking distance control (PDC) of automobiles, obstacle avoidance robots, construction sites and industrial working environments that require liquid level, well depth, pipeline length, etc. In general, there are two commonly used ultrasonic distance measurement methods:   - The ultrasonic ranging system based on single chip microcomputer or embedded equipment;   -  An ultrasonic ranging system based on CPLD (complex programmable logic device). In order to understand the design and application of ultrasonic ranging sensor, let us first understand the working principle of ultrasonic sensor. Introducing ultrasonic sensor & taking HC-SR04 as an example   Catalog   I What is ultrasonic sensor? II Methods for ultrasonic ranging III Principles for ultrasonic ranging IV Conclusion FAQ   I What is ultrasonic sensor?      Figure 1. Working principle of ultrasonic sensor ranging An ultrasonic sensor is a sensor that converts an ultrasonic signal into another energy signal (usually an electrical signal).  Ultrasonic is a mechanical shock wave generated in elastic media with a frequency greater than 20 kHz. Because of its strong directivity, slow energy consumption and relatively long propagation distance, it is often used in non-contact ranging.  In addition, ultrasonic has the big ability to penetrate liquid and solid, especially in the sunshine opaque solid. When an ultrasonic hits an impurity or an interface, itwill produce a significant reflection to form an echo,  and when it hits a moving object will cause a phenomenon called Doppler Effect.  Therefore, ultrasonic ranging has a good adaptability to the environment, and ultrasonic distance measurement can be well compromised in real time, precision, and price. II Methods for ultrasonic ranging At present, there are various methods for ultrasonic ranging:    -  round-trip time detection;   -  phase detection;   -  acoustic amplitude detection. The principle is that the ultrasonic sensor emits ultrasonic waves of a certain frequency, propagates through the air medium, and is reflected back after reaching the measurement target or the obstacle. After being reflected, the ultrasonic receiver receives the pulses, and the time it takes, is the round-trip time, which is related to the distance traveled by ultrasonic waves. Measuring the wave propagation time to get the wave propagation distance: Assuming that s is the distance between the measured object and the range finder, the time measured is t / s, and the velocity of ultrasonic propagation is expressed as v／m·s－1, then there is a relation (1): s=vt／2       (1) When the accuracy is required, the influence of temperature on the ultrasonic propagation speed needs to be considered, therefore the ultrasonic propagation speed is corrected according to relation (2) to reduce the error. v=331．4+0．607T        (2) Where T is the actual temperature, the unit is °C; v is the propagation speed of ultrasonic wave in the medium, and the unit is m/s. Figure 2. Working principle of ultrasonic ranging sensor   III Principles for ultrasonic ranging   The principle of ultrasonic ranging is to transmit ultrasonic waves in a specific direction through an ultrasonic transmitter, and start timing at the same time as the transmission. When ultrasonic waves propagate in the air and hit an obstacle, they will immediately return and be received by the ultrasonic receiver, and stop timing immediately. The ultrasonic ranging sensor uses the principle of ultrasonic echo ranging and uses precise time difference measurement technology to detect the distance between the sensor and the target. It has the advantages of small angle, small blind area, high measurement accuracy, non-contact ranging, waterproof, anti-corrosion, and low cost. Ultrasonic ranging sensors are usually used in a way that one transmitter corresponds to one receiver, but there are also multiple transmitters corresponding to one receiver. Therefore, the ultrasonic distance sensor can measure the return and return time of the ultrasonic wave to determine the distance of the object. This is how the ultrasonic distance sensor works. For the ultrasonic distance sensor, we recommend to use the Korean Hagisonic ultrasonic distance sensor module HG-C40U.   Figure 3. Ultrasonic distance sensor module HG-C40U   Ultrasonic distance sensor module has two optional transmission modes:   -  Free operation mode: when there is power supply, the sensor itself can send trigger and burst signals and it is usually for basic applications;   -  External trigger mode: the external system (controller or processor) controls trigger signals for advanced applications. These two modes are suitable for a variety of purposes.   In addition, the sensors also involve the choice of two input power supplies:   -  Low voltage (5V) for the processor circuit, the distance to the obstacle can be measured is 3.5m;   -  High voltage (12V) for the controller circuit, the distance to the obstacle can be measured is 5m. The data is transmitted by UART (universal asynchronous receiver-transmitter) with a resolution of less than 5mm. On the other hand, users can select different setting modes according to their own environment needs. Such as free-running / UART triggering / external trigger settings, etc.  At the same time, on the basis of baud rate of UART communication, the user can also decide whether to set up the circular buffer or not. The output signal uses high performance ASIC (application-specific integrated circuit) chip to ensure stable transmission and sensitive reception, and the communication between sensor and PC uses "interface board" (RS232, power regulator). The data show that the real received ultrasonic wave can be amplified in real time by using the monitor program on PC, the distance value can be output by UART (ASCII, mm), and then the detection signal can be converted into the rectangular TTL level signal (square wave) in real time. IV Conclusion Ultrasonic sensors are reliable, cost-effective and efficient solutions for distance sensing, level and obstacle detection. Once you understand how ultrasonic sensors work and which ultrasonic technology is most suitable rather than excellent, you can make more informed decisions about the correct sensor system for your application.   FAQ   1. What type of sensor is ultrasonic sensor? ultrasonic / level sensors measure the distance to the target by measuring the time between the emission and reception. An optical sensor has a transmitter and receiver, whereas an ultrasonic / level sensor uses a single ultrasonic element for both emission and reception.   2. How many types of ultrasonic sensors are there? four types. All together there are four types of ultrasonic sensors, classified by frequency and shape: the drip-proof type, high-frequency type, and open structure type (lead type and SMD type).   3. What is the range of ultrasonic sensor? For ultrasonic sensing, the most widely used range is 40 to 70 kHz. The frequency determines range and resolution; the lower frequencies produce the greatest sensing range. At 58 kHz, a commonly used frequency, the measurement resolution is one centimeter (cm), and range is up to 11 meters.   4. Can ultrasonic sensor detect human? Finally, ultrasonic sensors assist in detecting people for autonomous navigation of robots. Ultrasonic sensors can be used to set multiple tripwire distances to help navigate around people. Additionally, the high read rate allows you to quickly detect when a person may enter your robot's path.   5. Is ultrasonic sensor harmful? Occupational exposure to ultrasound in excess of 120 dB may lead to hearing loss. Exposure in excess of 155 dB may produce heating effects that are harmful to the human body, and it has been calculated that exposures above 180 dB may lead to death.   6. How do ultrasonic sensors work? Ultrasonic sensors work by emitting sound waves at a frequency too high for humans to hear. They then wait for the sound to be reflected back, calculating distance based on the time required. This is similar to how radar measures the time it takes a radio wave to return after hitting an object.   7. Why is ultrasonic sensor used? Ultrasonic sensors are used primarily as proximity sensors. They can be found in automobile self-parking technology and anti-collision safety systems. ... Ultrasonic sensors are also used as level sensors to detect, monitor, and regulate liquid levels in closed containers (such as vats in chemical factories).   8. Where are ultrasonic sensors used? Ultrasonic sensors have been used throughout many applications and industries. They are used within food and beverage to measure liquid level in bottles, they can be used within manufacturing for an automated process and control maximising efficiency on the factory floor.   9. Is ultrasonic sensor waterproof? Most ultrasonic distance sensors aren't waterproof which can be a problem if you need your project to withstand the elements outdoors. ... This sensor is suitable for outdoor applications such as car reversing sensors, security alarms, industrial inspection, etc.   10. Is ultrasonic sensor analog or digital? Usually, ultrasonic sensors are integrated with an Analog-to-Digital converter (ADC).   11. How do ultrasonic sensors measure distance? As the name indicates, ultrasonic sensors measure distance by using ultrasonic waves. The sensor head emits an ultrasonic wave and receives the wave reflected back from the target. Ultrasonic Sensors measure the distance to the target by measuring the time between the emission and reception.   12. How accurate is the ultrasonic sensor? The more accurate ultrasonic sensors can achieve 0.1 – 0.2% of the detected range under perfectly controlled conditions, and most good ultrasonic sensors can generally achieve between 1% and 3% accuracy.   13. What can ultrasonic sensors detect? Ultrasonic sensors can measure the distance to a wide range of objects regardless of shape, color or surface texture. They are also able to measure an approaching or receding object.   14. Are ultrasonic sensors affected by smoke? Ultrasonic sensors are superior to infrared sensors because they aren't affected by smoke or black materials, however, soft materials which don't reflect the sonar (ultrasonic) waves very well may cause issues.   15. Which is better ultrasonic or IR sensor? Ultrasonic sensors work using sound waves, detecting obstacles is not affected by as many factors. If reliability is an important factor in your sensor selection, ultrasonic sensors are more reliable than IR sensors. If you're willing to compromise reliability for cost, infrared sensors are ideal for your application.  

The devices or components commonly used in electronic circuits include: resistors, capacitors, inductors, sensors, potentiometers, transformers, diodes, bipolar junction transistors (BJTs), photoelectric switches, resonators, oscillators, filters, silicon controlled rectifiers (SCRs), relays, dual inline package (DIP) switches, fuse holders, bridge rectifiers, emitters, reed switches, common mode chokes and ferrite beads, magnetic rings, etc. This article contains a lot of commonly used electronic components figures, and I hope you will find this information useful.A Simple Guide to Electronic Components FAQ1. What are basic electronic components?You will work with a number of basic electronic components when building electronic circuits, including resistors, capacitors, diodes, transistors, and integrated circuits. 2. What are electronic components called?They are also called Electrical elements or electrical components. e.g. Resistors, Capacitors, Diodes, Inductors. 3. What are the 3 classification of electronic components?Classification of Electronic Components: Components can be classified as passive, active, or electro-mechanic components.Active components are devices that can amplify an electric signal and produce power.Passive components can't introduce net energy into the circuit. 4. What are the two types of electronic components?These are of 2 types: Passive and Active Components. 5. What is passive electronic components?A passive element is an electrical component that does not generate power, but instead dissipates, stores, and/or releases it. Passive elements include resistances, capacitors, and coils (also called inductors). These components are labeled in circuit diagrams as Rs, Cs and Ls, respectively. 6. How do I choose electronic components?How to select electronic components?Manufacturers.Application Circuit Complexity.Electrical Parameters [voltage, current, power, accuracy, response time, speed, resolution, etc.]Mechanical Parameters [dimension, package, weight, etc.]Consideration w.r.t Manufacturing / Testing. 7. What is difference between active and passive components?Active components are the elements or devices which are capable of providing or delivering energy to the circuit. Passive components are the ones that do not require any external source for the operation and are capable of storing energy in the form of voltage or current in the circuit. 8. How to Test Electric Components with a Multimeter?Continuity tests measure if electricity can flow through the part.Resistance tests how much current is lost as electricity flows through a component or circuit.The third common test is for voltage, or the force of the electric pressure. 9. What are passive components?A passive component is an electronic component which can only receive energy, which it can either dissipate, absorb or store it in an electric field or a magnetic field. ... Passive components cannot amplify, oscillate, or generate an electrical signal. Common examples of passive components include: Resistors. Inductors. 10. How do I choose a PCB component?6 tips for choosing PCB componentsThink about component footprint decisions.Use good grounding practices.Assign virtual parts footprints.Ensure you have complete BOM Data.Sort reference designators.Check spare gates. Relevant information about "List of Basic Electronic Components"About the article "List of Basic Electronic Components", If you have better ideas, don't hesitate to write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles:Rectifiers and Filters NotesCharacteristics and Functions of DiodesReview and Application of Electronic skinSwitched Mode Power Supply Tutorial: Principles & Functions of SMPS CircuitsTransformers Basics: Construction, Types, Materials and Design

Warm hints: The word in this article is about 3000 words and  reading time is about 10 minutes.   The transformer is a static electrical device, mainly composed of an iron core (or magnetic core) and coil. The coils have two or more windings, of which the ones connected to the power are called primary coils, and the rest are called secondary coils. Transformers are widely used in electrical equipment such as household appliances, electronic equipment, switching power supply, and so on. Circuit symbols commonly used T as the beginning of the number, for example, T01, T201.    This article covers the construction, functions, classification, and design of transformers and materials used for building magnetic cores in transformers.     Catalogs   I. The Composition of Transformer II. The Construction and Functions of Transformer III. High-frequency Transformer Design Program 3.1 Program structure 3.2 Matters needing attention when doing the core material   selection 3.3 Ferrite magnetic material requirements IV. Power Transformer Classification V. Principle and method of Transformer Design FAQ   I. The Composition of Transformer 1）The primary side 2）The secondary side 3）Magnetizing inductance 4）Leakage inductance 5）Open-circuit or short-circuit measurement of the primary side leads to the  Magnetic inductance and the leakage inductance turns ratio respectively:  K=Np/Ns=V1/V2   II. The Construction and Functions of Transformer 1) Electrical isolation 2) Energy storage 3) Voltage change for same power input.   III. High-frequency Transformer Design Program   3.1 Program structure (1) Core material (2) Core structure (3) Core parameters (4) Transformer Winding Parameter (5) package assembly (6) Temperature rise check   (1) Core material Soft magnetic ferrite is widely used in switching power supply because of its own characteristics. It has the advantages of high resistivity, low AC eddy current losses, low price, and easy to be machined into magnetic cores of various shapes. The disadvantages are low working magnetic flux density, low permeability, large magnetostriction, and high sensitivity to temperature changes. Which kind of soft magnetic ferrite material can satisfy the design requirement of a high-frequency transformer more fully, only when it is carefully considered and the transformer design can reach the high-cost performance.   (2) Magnetic core structure The factors considered in the selection of magnetic core structure are as follows: reducing magnetic leakage and leakage inductance, increasing the area of coil heat dissipation, which is beneficial for shielding and makes it easier to wind coils, more convenient to wire for assembly and so on.   The magnetic leakage and leakage inductance are directly related to the magnetic core structure . If the magnetic core does not need air gap, then a enclosed ring-like or square type magnetic core may be used as far as possible.   (3) Magnetic core parameters In the design of core parameters, special attention should be paid to the operating flux density only limited by the magnetization curve, but also by the losses, and also related to the working mode of power transmission. When the flux changes in one direction, there is ΔB=Bs-Br, which is not only limited by the saturation flux density but also mainly by the losses (Losses cause temperature rise, which in turn affects magnetic flux density). The operating flux density Bm=0.6～0.7ΔB.   An air gap can decrease Br and therefore increase the flux density ΔB. The exciting current can be increased after using an air gap opening, but the core volume can be decreased either. For the two-way operation of magnetic flux, the flux density ΔB is twice the maximum operating flux density Bm, that is ΔB=2Bm. In bidirectional operating mode, we should pay attention to the problem of transformer DC magnetic bias due to the inequality of volt-second areas of positive and negative excitation variation, which is caused by different reasons. A small air gap will be needed in the core, or a DC capacitor can also be added to the circuit design.   Magnetic properties of ferromagnetic materials Magnetic hysteresis loops of the core   (4) Coil parameters Coil parameters include: turns, conductor section (diameter), wire form, winding arrangement and insulation. The conductor section (diameter) depends on the current density of winding, using taking 2.5～4A/mm2. When doing some choosing of section conductor diameter don’t forget to take the skin effect into consideration and do regulations necessary after some temperature rise tests of the transformer.   General winding arrangements: the primary winding is close to the core and the secondary windings & feedback windings are gradually arranged outward. The following two winding arrangements are recommended:   1) If the voltage of the original windings is high (for example, 220V) and meanwhile that of the secondary windings is low, a more appropriate arrangement is the secondary winding being close to the core, and then goes the feedback winding, the original winding is arranged on the outermost ends, which is advantageous to the insulation arrangement of the original winding to the core;   2) If we want to increase the coupling between the primary and secondary windings, we can make half of the original windings be close to the core, then goes the feedback winding and secondary winding, and the other half of the original winding being the outermost ends, which is an arrangement advantageous to reduce the leakage inductance.   (5) Assembly structure The assembly structure of high-frequency power transformers are divided into horizontal and vertical types. If you'd like to select the planar core, sheet magnetic core and thin-film magnetic core, then a horizontal-type assembly would do you good.   (6) Temperature rise tests The temperature rise tests can be carried out by calculation and sample test. The temperature rise is lower than the allowable temperature rise above 15 degrees, the current density and the cross-section of the wire are appropriately increased. Appropriately increase the current density and decrease the cross-section of the wire, and do the exact opposite if temperature rise exceeds the allowable value, such as increasing the diameter or enlarging the core if necessary, to increase the area of coil heat dissipation.       3.2 Matters needing attention when doing the core material selection (1) Soft ferrite, due to its low price, good adaptability, and high performance at high frequency, has been widely used in switching power supply.   (2) Soft ferrite is commonly divided into two series: Mn-Zn ferrite and Ni-Zn ferrite. The Mn-Zn ferrite is composed of Fe2O3，MnCO3，ZnO and so on, which is widely used in all kinds of filters, inductors, transformers, and so on below 1MHz. The Ni-Zn ferrite is composed of Fe2O3，NiO，ZnO and so on, which is widely used in all kinds of adjustable inductor windings, anti-jamming magnetic beads, antenna matching devices, and so on above 1MHz.    (3) Mn-Zn ferrite is the most widely used core in switching power supply, and the selection of its material depends on its use. The core for the input filter part of the power supply is mostly high-conductivity magnetic core, and its material number mostly is R4K～R10K, that is, the ferrite core of relative permeability is about 4000~10000, but the main transformer and output filter are magnetic materials with high saturation flux density, where Bs is about 0.5T (5000GS).     3.3 Ferrite magnetic material requirements   Ferrite magnetic materials for switching power supply shall meet the following requirements:   (1) High saturation flux density Bs and low residual flux density Br   The residual flux density Bs has a certain influence on the transformer and winding results. Theoretically speaking, the number of turns of transformer windings can be reduced and the copper loss can be reduced because of the high Bs. In practical applications, there are different types of circuits of high-frequency converters in switching power supply.    For transformers, their operations can be divided into two categories:   1) Bipolar: The circuit topologies include half-bridge, full-bridge, push-pull, etc. In the primary winding of the transformer, the excitation current is equal and opposite in direction during the positive and negative half-cycles. Therefore, the magnetic flux changes in the magnetic core of the transformer are symmetrically moved up and down. The maximum variation range of B is  ΔB=2Bm, and the DC component of the magnetic core is basically canceling out.   2) Unipolar: The circuit topologies include single-ended forward, single-ended flyback, etc. The transformer primary winding adds a unidirectional square wave pulse voltage in one cycle (this is the case for single-ended flyback). The magnetic flux density varies from the maximum Bm to the residual flux density Br in the unidirectional-excitation transformer core. If we decrease the Br and increase the saturation flux density Bs, then the △B will be increased, and the turns and copper loss will also be reduced.   (2) Transformers or inductors are divided into three categories according to their topology:   1) An DC-filter inductor's magnetic core only works in one quadrant, the topologies of this operating state including Boost, Buck, buck/boost inductors, single end flyback converter transformer, forward and all push-pull converters and output filter inductors.   2) The core of the transformer in the forward converter also works in one quadrant, but the transformer needs to magnetic reset.   3) The core of the transformer with push-pull topology is in bidirectional alternating magnetization. These kinds of converters include push-pull, half-bridge and full-bridge converters, AC filter inductors, and so on.   (3) Low power loss at high frequency   The power loss of ferrite not only affects the power output efficiency but also leads to the heating of the magnetic core and waveform distortion.   The heating problem of the transformer is very common in practical applications, which is mainly caused by copper loss and core loss of the transformer. If the selected Bm is too low and the turns of winding are too many, it will cause the winding to heat up and transfer the heat to the core at the same time, and vice versa.   When selecting the ferrite material, we must make the power loss change with temperature characterized by a negative temperature coefficient. This is because if the core loss is the main heating, making the transformer temperature rise up, which then will lead to a further increase of core losses, thus it will form a vicious circle and eventually make the power tube, transformer, and other components burn down. Therefore, in the researches of power ferrite at home and abroad, we must solve the problem of negative temperature coefficient of magnetic material power loss itself, which is also a remarkable feature of magnetic materials having met the requirements for power supply applications, such as PC40 from Japanese company TDK and R2KB from China manufacturers and so on.   (4) A relatively moderate permeability   (5) How we choose the appropriate relative permeability?    Well, this depends on the switching frequency of your actual circuit, mostly 2000, meanwhile its applicable frequency must be below 300kHz, and sometimes can be a little higher, but the maximum will not be higher than 500 kHz.   (6) A relatively high Curie temperature   Curie temperature is the temperature at which a magnetic material loses its magnetic properties, generally above 200 ℃. However, the actual operating temperature of the transformer should not be higher than 80℃, at which the saturation flux density Bs will drop to 70% of that at the normal temperature when the temperature is above 100℃. That is, the saturation flux density of the core will drop more seriously when the operating temperature is too high. Furthermore, when the temperature is higher than 100℃, the power loss has been experiencing a positive temperature coefficient, which will lead to a vicious circle. For R2KB2 materials, the temperature corresponding to the allowable power consumption has reached 110℃ and the Curie temperature is up to 240℃, which meets the requirements of high-temperature use.     IV. Power Transformer Classification Power transformers are divided into three categories according to their topology: (1) Flyback transformers; (2) Forward transformers; (3) Push-pull transformers (full-bridge/half-bridge converters)   The appropriate topologies for various core structures are shown in the following table:   Core structureTypes of converter circuitFlybackForwardPush-pullE cores++0Planar E Cores-+0EFD Cores-++ETD Cores0++ER Cores0++U Cores+00RM Cores0+0EP Cores-+0P Cores-+0Ring Cores-++    "+"=fit; "0"=normal; "-"=unfit Summary of High frequency transformer core.XLS V. Principle and Method of Transformer Design   (1) There are two main ways to design transformer: Area Product (AP) Method AP: The product of core effective cross section Ae and Area of window Aw PT-The calculation power of the transformer Ae-Core effective cross section Aw- Area of window Ko-Core window utilization coefficient, typically 0.4 Kf-Waveform coefficient, usually square wave being 4 and sine wave being 4.44 Bw-The operating magnetic intensity of core FS-Switching frequency Kj-Current density coefficient, usually 395A/cm2 X-Core structure coefficient     (2) According to the area product (AP) method, the general steps of designing transformer are as follows: 1. Select the core material to calculate the apparent power of the transformer; 2. Determine the core cross section AP and select the core size according to AP value; 3. Calculation of the primary side inductance and the number of turns; 4. Calculation of the length of air gap; 5. Calculating the line diameter according to the current density and the secondary side RMS current. 6. Determine whether the copper loss and iron loss meet the requirements (eg allowable loss and temperature rise)   Selecting the flyback topology, the basic parameters of the power supply are as follows: Input voltage: 175-264 VAC Output voltage: 21V Output current: 3A Output power P0=63W Frequency set at 60Khz Duty cycle set at 0.45 initially   1) Select the core material to determine the apparent power PT of the transformer   and select the PC40 material here considering the cost factor and check the PC40 data to get Bs=0.39T, Br=0.06T. In order to prevent the core from becoming saturated instantly, a certain margin is reserved. Let Bm= ΔBmax*0.6=0.198T, and pick up the 0.2T. For flyback topology, the transformer apparent power PT is:   2) Calculating AP values with Excel tables   Where, J is the current density, usually 395A/cm2, and Ku is the effective use coefficient of copper window, usually 0.2～0.4, now we set Ku as 0.4.    Based on the figure above, we select the core EE3528 due to its being greater than the calculated AP value, with the following parameters: Ae: 84.8mm2 AP：1.3398cm4 Wa：158mm2 AL：2600nH/H2 In order to adapt to the abrupt load current, the power supply is designed in critical mode and the critical current is: I0B=0.8×I0=2.4A     3) Calculation of the primary side inductance and the number of turns (A) Minimum input voltage Vimin=ViACmin*1.2=210V (B) Turns ratio n=[Vimin/(V0+Vf)]*[Dmax/(1-Dmax)] n=[210V/(21V+1V)*[0.45/(1-0.45)] n=7.8 (C) Peak secondary current ^IsB=2*IoB/(1-Dmax) ^IsB=2*2.4A/(1-0.45) ^IsB=8.72A (D) Secondary inductance Ls=(V0+Vf)*(1-Dmax)*[1/(Fs*1000)]/^IsB*1000000 Ls=(21V+1V)*(1-0.45)*[1/(60Khz*1000)]/8.72A*1000000 Ls=23.58Uh (E) Primary inductance Lp=n*n*Ls Lp=7.8*7.8*23.58uH Lp=1434uH   Primary and secondary peak currents (F) Calculation of peak secondary current in continuous mode ^Isp=Io/(1-Dmax)+(^IsB/2) ^Isp=3A/(1-0.45)+(8.72A/2) ^Isp=9.81A (G) Calculation of peak primary current in continuous mode ^Ipp=^Isp/n ^Ipp=9.8A/7.8 ^Ipp=1.257A (H) Calculating the turns of the primary and secondary auxiliary windings a) Number of turns in the primary side Np=Lp*^Ipp/(^B*Ae) Np=1434uH*1.257A/(0.2*84.8) Np=106.28T After rounding: Np=106T b) Number of turns in the secondary side Ns=Np/n Ns=106T/7.8 Ns=13.58T After rounding: Ns=14T c) Number of feedback turns Nv=(Vcc+Vf)/[(V0+Vf)/Ns] Nv=(14.5V+1V)/[(21V+1V)/14T] Nv=9.87T After rounding: Nv=10T   To avoid core saturation, an appropriate air gap is added to the magnetic loop, the calculation go as follows: The number of turns may need to be corrected by the air-gap flux edge effect.   4) There are two ways to calculate the wire diameters of the primary, secondary and auxiliary windings: Effective current of original side diameter: Iprms=Po/^n/Vimin Iprms=63W/0.8/210V Iprms=0.375A (A) Calculating the area of bare wire (B) Calculating the wire diameter (current density J to take 4A/mm2) Using two 0.18mm-diameter wires wound around or AWG #28 a single strand The secondary diameter: Use four wires with a diameter of 0.25mm (AWG #31) and wind around. Calculation of Skin Depth: The diameter of multi-strand parallel winding must be less than or equal to dwH, in single wire winding, however, if the diameter exceeds the dWH value,  the multi-strand wire winding should be taken into account.   5) Calculation of copper loss Pcu and iron loss Pfe (total transformer loss Ploss) (A) Calculating the loss of primary and secondary windings.  Where, MLT is the average turn length of magnetic core (B) Calculating the allowable total loss Ploss and allowable iron loss at efficiency η (C) According to the loss curve of iron core, the actual loss (iron loss per unit weight and actual iron loss) is obtained by: The Ploss is the loss of the whole circuit, including diode/MOSFET losses and other losses, the actual losses Pfe must be much smaller than the calculated one, so here is only for reference. (D) Calculating the loss per unit area by Φ=Ploss/As If the temperature rise caused by Φ is less than 25 degrees, then the design is wonderful.   6) Calculating the BW The working flux density BW should be below Bs-Br within the design specifications, that is Bw<Bs-Br, to avoid saturation of the core.   FAQ   1. What is the use of transformer? Transformers are employed for widely varying purposes; e.g., to reduce the voltage of conventional power circuits to operate low-voltage devices, such as doorbells and toy electric trains, and to raise the voltage from electric generators so that electric power can be transmitted over long distances.   2. What are the 3 types of transformers? There are three primary types of voltage transformers (VT): electromagnetic, capacitor, and optical.   3. What is the basic principle of transformer? A transformer consists of two electrically isolated coils and operates on Faraday's principal of “mutual induction”, in which an EMF is induced in the transformers secondary coil by the magnetic flux generated by the voltages and currents flowing in the primary coil winding.   4. Does a transformer convert AC to DC? A transformer is built to transfer the energy from one circuit into another circuit by way of magnetic coupling. ... An alternating current creates a magnetic flux in the core on its way through the first winding, inducing the voltage in the others. It can convert high and low voltages, it cannot convert AC to DC.   5. What are the main parts of transformer? There are three basic parts of a transformer: a. an iron core which serves as a magnetic conductor, b. a primary winding or coil of wire and. c. a secondary winding or coil of wire.   6. What are the classification of transformer? Depending upon the type of construction used, the transformers are classified into two categories viz.: (i) Core type, and (ii) Shell type. Depending upon the type of service, in the field of power system, they are classified as: (i) Power transformers, and (ii) Distribution transformers.   7. Can a transformer work on DC? As mentioned before, transformers do not allow DC input to flow through. This is known as DC isolation. This is because a change in current cannot be generated by DC; meaning that there is no changing magnetic field to induce a voltage across the secondary component.   8. How do you convert a transformer? This conversion is made by winding two separate conductors around a common iron core. Applying an alternating voltage to the primary conductor produces current which sets up a magnetic field around itself. This is known as mutual inductance.   9. What are two components of no load current in transformer? The no-load current of a transformer consists of two components: The Magnetization Current iM is the current required to produce the flux in the transformer core. The Core-loss Current ih+e is the current required to make up for hysteresis and eddy current losses.   10. Which type of transformer core is most efficient? SHELL CORE. The most popular and efficient transformer core is the SHELL CORE, as illustrated in figure (4). As shown, each layer of the core consists of E- and I-shaped sections of metal. These sections are butted together to form the laminations.   You May Also Like: Analysis of Calculation Theory for Transformer Temperature Rise Some suggestions about protecting transformers Learn Some Basic Knowledge about Capacitor Voltage Transformer      

Warm hints: The word in this article is about 2500 words and reading time is about 12 minutes.   This paper mainly introduces that how to use a solid state relay to drive a thermostat.    As we all known,relay is an electrical control device, an electrical appliance that makes the predetermined step change in the electrical output circuit when the input (excitation) changes reach the required requirements. Catalog   I. Solid State Relay Basics 1.1    What is solid state relay 1.2    Solid state relay working principle 1.3    Solid state relay appliances II. Thermostat Basics 2.1    What is thermostat 2.2     Types of thermostat 2.3    Features of thermostat 2.4    Applications of thermostat III. Drive Thermostat by Using Solid State Relay 3.1    Power thermostat 3.2    Case of driving thermostat FAQ   I. Solid State Relay Basics   1.1 What is Solid State Relay   A solid-state relay(SSR) is a contactless switch consisting of microelectronic circuits, discrete electronic devices and power electronic power devices. The isolation between the control end and the load side is realized by isolation devices. The input of the solid-state relay is controlled by a tiny control signal to directly drive the large current load.   SSR takes advantage of the switching characteristics of electronic components, such as switch triode, bidirectional thyristor and other semiconductor devices, to achieve the purpose of connecting and disconnecting the circuits without contact and sparkless, and therefore is also called "contactless switch".    A solid-state relay is a four-terminal active device, of which two terminals are input control terminal, and the other ends are output controlled ends. It has both amplification and isolation function. It is suitable for driving high power switching actuator, which is more reliable than electromagnetic relay and has no contact, long life, fast speed and interference to the outside. Because of its small size, it has been widely used.   1.2  Solid State Relay Working Principle   SSR can be divided into two types: AC type and DC type according to the use occasions.    They can switch loads on AC or DC power supply, and they can not be mixed. The following is an example of the AC type SSR as an example of its working principle. The following diagram is a block diagram of its working principle. The components in the diagram constitute the main body of the AC SSR. From the whole, SSR has only two inputs (A and B) and two output terminals (C and D), and is a four-terminal device.   Working principle block diagram of solid state relay   When a certain control signal is added to the A and B, the "switch" and "break" between the two ends of C and D can be controlled and the function of "switch" can be realized. The function of the coupling circuit is to provide a channel between the input/output terminal of the control signal input from the A and B ends, but it disconnects the input and output terminals of the SSR in the electrical circuit.    In order to prevent the effect of the output end on the input end, the coupling circuit used the "optical coupler", which is sensitive, responsive, and high in the input/output insulation (voltage resistance) level; because the input terminal load is a light-emitting diode, this makes the input end of the SSR easily matched with the input signal level. When used, it can be directly connected to the output interface of the computer, that is, the logical level control of "1" and "0".    The function of the trigger circuit is to generate the required trigger signal, drive the switch circuit 4, but because the switch circuit does not add the special control circuit, it will produce the radio frequency interference and pollute the power grid such as the high order harmonic or the peak, so the zero-crossing control circuit is set up. The "zero crossings" means that when the control signal is added and the AC voltage is over zero, the SSR is a passing state, and when the control signal is broken, the SSR is to wait for the junction point (zero potential) of the positive half of the alternating current and the negative half of the half-week (zero potential), and the SSR is broken.    This design can prevent high-order harmonic interference and pollution to the power grid. The absorption circuit is designed to prevent the shock and interference (or even misoperation) of the peak, surge (voltage) transmitted from the power supply to the bidirectional thyristor in the switch device, usually using an "R-C" series absorption circuit or a nonlinear resistor (varistor).   1.3  Solid State Relay Appliances   The special solid-state relay can have the function of short circuit protection, overload protection and overheating protection. With the combined logic curing package, the intelligent module can be realized by the user. It is directly used in the control system.   Solid-state relay has been widely used in computer peripheral interface equipment, thermostat system, temperature regulating, electric furnace heating control, motor control, CNC machine, remote control system, industrial automation device, signal light, light adjustment, scintillator, lighting stage lighting control system, instruments, medical instruments, duplicator, automatic laundry. Machine, automatic fire protection, security system, and power capacitor switching switch as power factor compensation for the power grid, and so on, in addition to the chemical, coal mine, explosion-proof, anti-corrosion, corrosion prevention and so on. The logical curing encapsulation can realize the intelligent modules that users need and is directly used in the control system.     II. Thermostat Basics   2.1  What is Thermostat   The thermostat is a device that directly or indirectly controls one or more hot and cold Yuanlai to maintain the desired temperature. In order to achieve this function, a thermostat must have a sensitive element and a converter. The sensitive element can measure the change of temperature and produce the function required for the converter. The converter converts the function from the sensing element to the proper control of the device that changes the temperature. Thermostat 2.2 Types of Thermostat The types of the thermostat are generally the following: （1）Insert thermostat is installed on the pipe and sensitive element is inserted into the pipeline. （2）Immerse sensitive elements immersed in liquid in pipes or containers to control liquids. （3）Surface sensitive elements installed on the surface of pipes or similar surfaces.   2.3  Features of Thermostat This thermostat pressure gauge setting range (5~35 C) This thermostat measurement accuracy: plus or minus 1 DEG C The thermostat. Size: 86 x 86 (mm) Power supply: AC220V thermostat. This thermostat using ultra-thin design, electrical interface It has a large LCD screen with an LCD thermostat (backlight green, Lan Beiguang) You can display the thermostat in international language (Chinese + English) The thermostat has the function of automatic and manual. This thermostat for refrigeration heating and ventilation three working modes This thermostat high low-speed automatic selection Thermostat timing shutdown function. This thermostat control fan coil end of the fan, water valve, air valve You can also set the password on the thermostat setting temperature and wind speed according to the requirements of users.   Features of thermostat 2.4  Applications of Thermostat   The most common use of the thermostat is to control the room temperature.   Typical uses include: control the gas valve; control the fuel furnace regulator; control the electric heating regulator; control the refrigeration compressor; control the gate regulator.   A room temperature regulator can be used to provide a variety of control functions, such as heating control, heating - cooling control, day and night control (at night at lower temperatures), multistage control, primary or multistage heating, primary or multistage cooling, or multistage heating and cooling control.       III. Drive Thermostat by Using Solid State Relay   3.1  Power Thermostat   There are two kinds of power supply for the thermostat: battery and 24VAC power.    The thermostat needs battery power to run without interruption. It is very important that these batteries consume as low energy as possible, but even if you minimize the power consumption, the users are still inconvenient because the battery needs to be replaced from time to time. In order to reduce the replacement frequency, you can use a 24 VAC power supply. When the C line in the system is not available, the bridge rectifier shown in Figure 1 can convert the AC (AC) voltage to a DC (DC) voltage by the load. Single thermostat signal relay connection with HVAC load   3.2  Case of Driving Thermostat When the HVAC load (compressor, fan, gas valve, etc.) is turned off, the contact of the signal relay is broken. When the contacts are open, the terminals of the rectifier bridge see the voltage of the HVAC transformer is 24VAC, and convert the AC power to DC power, as mentioned earlier. The resulting DC voltage is used to drive the thermostat or subcircuit.   During the HVAC load conduction, the contacts of the signal relay are closed. When the contact is closed, the voltage across the bridge terminal is reduced to zero. This eliminates the need to use 24VAC as a power supply, so the thermostat battery power must be controlled. The range of current required for operating electromechanical relays ranges from tens to hundreds of Ma, which can have a significant impact on battery life.   If there is a way to drive a relay without using a thermostat battery, what will happen? Battery life will increase and replacement frequency will be further reduced. One way is to turn on the relay and charge the control system briefly during the HVAC load conduction (signal relay contact closure).  Compared with the turn off time of the power relay, the time required during charging is very short, which can stimulate the power relay and its corresponding load. Unfortunately, electromechanical (signal) relays are not likely to achieve this goal due to their switching speed limits. The time taken by the contact to the desired location is in milliseconds and will interrupt the HVAC load.   Fortunately, a device can achieve the appropriate switching speed: solid-state relay (SSR). SSR is a semiconductor repeater based on a thyristor or power transistor to perform on / off control.   This recharge method requires a dual MOSFET SSR because it can turn off MOSFET based SSR when necessary. Besides, body diodes of each MOSFET can assist in 24VAC rectification. A full-wave rectifier bridge is built with two diode MOSFET diodes, as shown below.   A power supply for SSR in a HVAC system The following figure shows the rectified waveform corresponding to the color coded diode in the above figure. The voltage ripple of the final waveform can be eliminated by connecting a suitable capacitor to the output of the rectifier bridge. Then, you can reduce the DC voltage of the control system to the desired voltage. Full wave rectifying waveform The use of SSR enables the HVAC system to fully supply the thermostat and reduce the power utilization rate of the battery. When SSR closes, the HV1 and HV2 pipelines will see the full 24VAC voltage and provide a constant 33VDC voltage at the output of the rectifier bridge. When SSR is connected, it may still be circulated through a short-time on/off state to recharge the power supply capacitor. This design can greatly reduce the energy requirements of the thermostat battery and reduce the battery replacement frequency.   FAQ   1. What is solid state relay and how it works? A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage (AC or DC) is applied across its control terminals. It serves the same function as an electromechanical relay, but has no moving parts and therefore results in a longer operational lifetime.   2. What is the difference between a relay and a solid state relay? The main difference between solid state relays and general relays is that there is no movable contacts in solid state relay (SSR). In general, solid state relays are quite similar to the mechanical relays that have movable contacts. ... SSR provide high-speed, high-frequency switching operations.   3. How fast is a solid state relay? The SSR output is activated immediately after applying control voltage. Consequently, this relay can turn on anywhere along the AC sinusoidal voltage curve. Response times can typically be as low as 1 ms. The SSR is particularly suitable in application where a fast response time is desired, such as solenoids or coils.   4. Do solid state relays get hot? All solid state relays develop heat as a result of a forward voltage drop through the junction of the output device. Beyond a point, heat will cause a lowering (or derating) of the load current that can be handled by the SSR. ... Loads greater than 4 Amps will require heat sinks.   5. What causes solid state relay failure? What are the main causes and solutions of the Solid-state Relays (SSR)'s failures? If an inrush current exceeds the rated making current of the SSR due to the high inrush current of loads such as motors and lamps, SSR output elements are damaged. Consider using an SSR with a higher capacity.   6. Can a solid state relay switch DC? Solid state relays can be designed to switch both AC or DC currents by using an SCR, TRIAC, or switching transistor output instead of the usual mechanical normally-open (NO) contacts.   7. How do you test a solid state relay with a multimeter? Using Multimeter:  1. Set the multimeter in continuity test mode. 2. Place the probes of the multimeter on the coil terminals. 3. If the multimeter beeps (or show any sign of continuity), the coil is electrically closed (good). 4. If the multimeter does not beep, the coil is open & damaged. The relay needs to be replaced.   8. How reliable are solid state relays? Solid-state relays are the preferred choice for system reliability because they have no moving parts or contacts. Over time, the plating on the contacts inside EMRs can erode. This erosion can cause the contacts to weld shut; therefore they no longer open/close properly, and the relay has to be replaced.   9. Is a solid state relay a transistor? Solid-State Relay: A sort of hybrid between a conventional relay and a transistor, these relays switch a load using an LED activated by the control circuitry. The LED activates a light-activated MOSFET that controls the load.   10. How do I know if my solid state relay is bad? Solid-state relays should be checked with an ohmmeter across the normally open (N.O.) terminals when control power is off. The relays should be open, switched to OL, and closed (0.2 , the internal resistance of the ohmmeter) when control power is applied.   11. How do I choose a solid state relay? When selecting a Solid State Relay, consider: Current rating, as a general rule consider using the relay at no more than 70% of its rated current. Electrical environment,. i(In harsh electrical environments, consider a relay with an line voltage rating above the application line voltage.)   12. Do solid state relays need a diode? 2 Answers. The control side of solid state relays is usually just a LED, sometimes two LEDs back to back, and sometimes with integrated resistor. ... If the relay is on the same board as whatever is driving it, then no inductive kickback diode is needed. It's no different than driving any other on-board LED.   13. Do solid state relays leak voltage? Solid State relays have leakage. If you want to repeatedly switch something on / off, use them. But when you want the SSR to be fully off, say after pressing an off switch, a mechanical relay should be across the load to take it off the SSR. ... The SSR control is attached to the atmega328 through a 200ohm resistor.   Relevant information about "How  to Drive Thermostat by Using Solid State Relay " About the article "How  to Drive Thermostat by Using Solid State Relay", If you have better ideas, don't hesitate to write your thoughts in the following comment area. You also can find more articles about electronic semiconductor through Google search engine, or refer to the following related articles.   Making a Arduino Variable Timer Relay Comprehensive Introduction of the Time Delay Relays

A high-output-power balanced power amplifier is designed with power-combining architecture for satellite communication terminals. The power-combining architecture introduces a ±45° phase shift in the output matching network of two amplifiers, which makes the balanced power amplifier more tolerant to load mismatch and less sensitive to load variation. This balanced power amplifier is implemented with InGaP/GaAs HBT process. Under the band of 1.5 GHz to 1.7 GHz and the supply voltage of 5 V, the measured results show that 32 dB of the gain, 38 dBm of the saturated output power and 43% of power added efficiency (PAE) are achieved, and a good radio frequency performance can be maintained under load mismatch conditions. Power Amplifier ( PA ) Basics and fundamental tutorial on radio frequency   Catalog Ⅰ Introduction of Power Amplifier 1.1 Background of power amplifier 1.2 Application of power amplifier in   power combination scheme 1.3 High power balanced power amplifier Ⅱ Design and Analysis of balanced Power   Amplifier 2.1 Design of Integral circuit 2.2 Circuit Analysis Ⅲ Test result Ⅳ Conclusion FAQ     Ⅰ Introduction of power amplifier 1.1 Background of power amplifier In recent years, with the development of economy, satellite communication and navigation systems are widely used in electronics and automobile industry,and the demand for power amplifiers of handheld terminal transmitters is increasing.These power amplifiers require greater power output and better stability to meet the performance requirements of satellite communications and navigation systems. Therefore, it is of great significance to study the practical and reliable high power integrated power amplifier used in the handheld terminal of satellite communication and navigation system. The traditional single-terminal multi-stage integrated power amplifier is not only low in output power, due to the influence of its own semiconductor physical characteristics and the limitations of processing technology, heat dissipation, impedance matching, etc, but the output power will also decrease rapidly with the increase of frequency. In order to improve the output power, the power combination technology is a practical and easy method to implement. At the same time, the balanced power amplifier is widely used in the power synthesis scheme because of its insensitive load and wider bandwidth than the single-ended power amplifier.    1.2 Application of power amplifier in power combination scheme In reference, a high linearity and high efficiency power amplifier is realized by balanced synthesis method. The power amplifier has the advantages of flat gain characteristics and more stability than the corresponding single-ended amplifier in a wide band. However, the introduction of orthogonal 3dB couplers at the input and output ends makes the power amplifier require more discrete devices, which is not conducive to miniaturization and integration. In reference, a novel balanced synthesis architecture was used to design a load insensitive power amplifier.This kind of power amplifier adds ±45 °phase shift network to the upper input and lower output terminals, and finally combines the two power channels through the Wilkinson synthesizer at the output end. This design not only achieves high efficiency and linearity, but also has good stability when the load changes. It is widely used in 3G WCDMA mobile phone terminals. However, the introduction of Wilkinson synthesizer also brings many disadvantages, such as large insertion loss, increasing integration cost and complexity. In reference, on the basis of reference, the ±45°phase shift network in the output end of the power amplifier is improved and optimized, the Wilkinson synthesizer is removed either, which makes the power amplifier insensitive to the load change while achieving high efficiency and high linearity.This design reduces the integrated devices, reduces the cost, and is widely used in modern 3G smart phone terminals.   1.3 High power balanced power amplifier Based on the comprehensive consideration of output power and stability, a high power balanced power amplifier based on InGaP/GaAs HBT process, operating in the 1.5-1.7 GHz band, is designed in this article. The test results show that the balanced power amplifier has high output power and power addition efficiency (PAE), and the circuit can still maintain good RF performance when the load mismatches. Ⅱ Design and analysis of balanced power amplifier 2.1 Design of Integral circuit  Due to the superior linearity and high efficiency of HBT process in RF IC design, a balanced power amplifier working in 1.5-1.7 GHz band is designed by using InGaP/GaAs HBT process in this article. The overall circuit structure is shown in figure 1. The balanced power amplifier circuit includes the same upper and lower branch amplifiers, and the input and output matching circuits of ±45°phase-shifting networks. In order to obtain a higher gain, the upper and lower branches are designed using a three-stage power amplifier structure, in which the first stage works in a class A to obtain a high linearity; in order to take into account the linearity and efficiency of the overall power amplifier, the second and third stages work in Class AB.   Figure 1. A balanced power amplifier circuit   In order to achieve a good compromise between efficiency and linearity, the biasing circuit adopts self-adaptive linearizing bias.By adding one inductor and one capacitance to the input matching circuit of the upper and lower branches, the balanced power amplifier generates ±45°phase shift to the input signal, thus realizing that the upper and lower channels of the amplifier work in an orthogonal state. A LC resonant network with a resonant frequency of 2Ω0 is added to the output matching, where Ω0 is the fundamental frequency, which is equivalent to getting a load of second harmonic short circuit at the same time, thus realizing the suppression of the second harmonic. The structure is similar to that of F power amplifier, and is beneficial to obtain higher efficiency. The main characteristic of the circuit in this article is that the output matching circuit of the upper and lower branches added a ±45°phase shift network, the upper branch adds a -45°phase shift network with a low pass filter structure, and the lower branch adds a +45°phase shift network with a high pass filter structure. The balanced power amplifier designed by this synthetic structure has the advantages of small space usage, simple structure and easy implementation. At the same time, it can make the balanced power amplifier more tolerant to load mismatch and insensitive to the change of load.   2.2 Circuit Analysis When the balanced power amplifier is in operation, the input signal is coupled to the A node through the blocking capacitor, and two signals are separated from the A node into the upper and lower branches respectively, because the three-stage amplifier in the upper and lower branches is exactly the same, they sharing an equal input impedance, so the power of the two signals separated at the A node is equal. The separated signals are transmitted to the input end of the amplifier through the opposite 45°phase change of the upper and lower branches respectively, and then the orthogonal signals are amplified by the three-stage amplifier of the upper and lower branches. The orthogonal signal of the upper and lower branches undergoes an opposite phase shift of 45° in the output matching network, so the same signal with the same phase and the same amplitude is realized at point B, and the output power of point B is the sum of those of the two amplifiers, finally the balanced power amplifier can obtain higher output power. The balanced power amplifier is equivalent to the three-port network shown in figure 2. Because the upper and lower branch of amplifiers are exactly the same,it can be considered that the amplifiers of the upper and lower branches have the same output reflection coefficient ΓPA. After passing through ±45°phase shift network, we can obtain ΓPAе −j2ΔΦ and ΓPAе +j2ΔΦ respectively. Therefore, the equivalent output impedance of the upper and lower branches viewed from the ab surface to the left in figure 2 is respectively as follows:   The equivalent output impedance ZL of the network viewed from the terminal to the left can be obtained in parallel by ZL1 and ZL2: The output reflection coefficient of node B is: By substituting formula (1)-(3) into equation (4) and simplifying, the output reflection coefficient of the balanced power amplifier is as follows: When ΔΦ=45°, you have: It is shown that the output reflection coefficient and VSWR of the balanced power amplifier are twice as much as that of the single branch power amplifier. Therefore, when the load mismatch occurs, the load mismatch tolerance of the balanced power amplifier is higher than that of the single-branch power amplifier after the ±45°phase shift output matching network is introduced. Figure 2. Circuit equivalent diagram In order to analyze the performance of the balanced power amplifier in the case of load mismatch, the equivalent circuit of figure 2 is simulated and analyzed. When the load mismatch (such as VSWR=3:1), the load impedance (normalized) of the upper and lower branch amplifiers varies with the phase ψ of the reflection coefficient Γ, as shown in figure 3. By comparing the load impedance of the upper and lower branches, it can be seen that they have a phase difference of 180°. Because of the change of the load impedance of the upper and lower branches, the corresponding current is changed, and the phase difference of 180°occurs between the two. The collector of the two third-stage amplifiers of the balanced power amplifier is single power supply, so the current of the upper and lower branches compensates each other, resulting in little change in the total current, as shown in Figure 4. Therefore, when the load mismatch of the balanced power amplifier occurs, the change of working current is relatively small, that is, not sensitive to the change of load. The load insensitive effect of using this balancing architecture is similar to that of classical balanced power amplifier which is realized by using orthogonal 3 dB coupler. Figure 3. Changes in the load of the structure (normalized) when VSWR=3:1 In the case of terminal mismatch (VSWR=3:1), the single end circuit architecture and the present balanced architecture are compared as shown in Fig. 5 with the same output power of 38 dBm. It can be seen from figure 5 that the output power of the single-ended circuit architecture fluctuates greatly with of the phase ψ of the reflection coefficient Γ, while the output power of the balanced architecture in this article is relatively flat. At the same time, compared with the circuit architecture without phase shift, the in-phase circuit architecture has more advantages than the single-ended circuit architecture, but the output power of the balanced architecture is the flattest and can work stably. Figure 4. Changes of current of the structure (normalized) when VSWR=3:1 Figure 5. Comparison with the output power (normalized) changes in three kinds of circuits when VSWR=3:1   Ⅲ Test result  In this post, the balanced power amplifier is fabricated by InGaP/GaAs HBT technology. The three-stage amplifier and bias circuit with upper and lower branches are realized in the chip with an DIE area of 0.9 mm×0.8 mm. The choke inductor, input matching and output matching circuit are realized out of the chip. Considering the heat dissipation of the power amplifier, the whole thing is integrated on the Fr4 substrate with an area of 8 mm×8 mm. Figure 6 is the physical diagram of the circuit.The working voltage of the balanced power amplifier is 5 V and the total static current is about 310 mA. Using Agilent's network analyzer E5071C to measure the small signal S parameters S21, S11, S22 of the balanced power amplifier, as shown in figure 7: S21 > 31 dB (in the band of 1.5 GHz-1.7 GHz with a variation of less than 1 dB) S11 < -12 dB S22 < -10 dB The test results show that the design has good small signal performance. Using Agilent's signal generator N5182A and spectrometer N9030A to build the test platform, inputting continuous wave (CW) and the performance of the balanced power amplifier is measured at 1.5,1.616 and 1.7 GHz, as shown in figure 8. It can be seen from the diagram that the gain of the balanced power amplifier in the frequency band is about 32 dB, the in-band gain flatness is ±0.3 dB, the saturation power is more than 38 dBm/6.3 WN, and the power additional efficiency is greater than 43 dB. At the same time, according to the gain curve of each frequency point, the balanced power amplifier has good AM-AM characteristic and 1dB compression point is about 37 dBm. The third order intermodulation distortion (IMD3) and the fifth order intermodulation distortion (IMD5) of the balanced power amplifier are measured by using a two-tone signal with a deviation of 2 MHz, as shown in figure 9. The results show that the balanced power amplifier has good linearity. In general, the balanced power amplifier not only has high gain, high output power and high efficiency, but also has good linearity.  Figure 6. Chip physical diagram Figure 7. S parameter test results Figure 8. Test performance in frequency band when CW signal is input In order to verify the tolerance of the balanced power amplifier to the load mismatch and the load insensitivity, and the balanced power amplifier can still work properly when VSWR=20:1, a microwave manual tuner is connected to the output of the power amplifier. And when the working frequency is 1.616 GHz, the input power Pin=10 dBm and voltage standing-wave ratio VSWR=3:1, the output power of the balanced power amplifier changes with the reflection coefficient phase, as shown in Figure 10. The figure shows that the output power is about 35.7 dBm, with a range of ±0.7 dBm. Therefore, the performance of the balanced power amplifier is stable when the load is mismatched to a certain extent. Figure 9. Test performance of IMD3 and IMD5 Figure 10. Changes of output power when VSWR=3:1 Ⅳ Conclusion In this post, a high power balanced power amplifier is designed by using the balance architecture, the chip area is 8 mm×8 mm by using InGaP/GaAs HBT process and the total static current is about 310 mA at a operating voltage of 5V. When the CW signal is input, the gain can be up to 32 dBm in the band of 1.5-1.7 GHz, the saturation output power psat is 38 dBm, and the additional power efficiency is 43%. Beyond that, it can still work stably when the load mismatches. This balanced power amplifier is practical, reliable and safe, and can be used in handheld terminal of the satellite communication and navigation system.   FAQ     1. What is a power amplifier used for? The function of a power amplifier is to raise the power level of input signal. It is required to deliver a large amount of power and has to handle large current. The base of transistor is made thicken to handle large currents.   2. How does a power amplifier work? The power amplifier works on the basic principle of converting the DC power drawn from the power supply into an AC voltage signal delivered to the load. Although the amplification is high the efficiency of the conversion from the DC power supply input to the AC voltage signal output is usually poor.   3. Does a power amp make a difference? A better amp will make your speakers play louder and sound better, but it won't make bad speakers sound like good speakers. Many speakers have a "maximum wattage rating" on the back. ... High-end amplifier companies make amps with more than 1,000 watts, and you could plug in a $50 speaker into it with no problem.   4. What is power amplifier circuit? A power amplifier circuit is used to drive the loads like speakers with minimum output impedance. ... In this mode the output is an inverted amplified signal which is at low power. Two Darlington power transistors are arranged in a class AB configuration to amplify the power level of this signal.   5. How do you make a power amp circuit? Amplifier power gain and design. As power is the voltage multiplied by the current in a circuit, the power gain can simply be expressed as the product of the two. It is also possible to use the voltage and current levels to provide gain expressed in dB, but any changes in impedance must be accounted for.   6. What is balanced amplifier? A balanced amplifier has two amplifying devices that are run in quadrature. That is, they are operating 90 degrees apart in transmission phase. ... Balanced amplifiers may more immune to load pull effects than in-phase power combining schemes, because the two reflection coefficients are seen 180 degrees out of phase.   7. What is the difference between amplifier and power amplifier? The crucial difference between a voltage amplifier and a power amplifier is that a voltage amplifier increases the voltage level of the applied input signal.   8. Why do we need power amplifier? The function of a power amplifier is to raise the power level of input signal. It is required to deliver a large amount of power and has to handle large current. The base of transistor is made thicken to handle large currents.   9. What power amplifier do I need? Generally you should pick an amplifier that can deliver power equal to twice the speaker's program/continuous power rating. This means that a speaker with a “nominal impedance” of 8 ohms and a program rating of 350 watts will require an amplifier that can produce 700 watts into an 8 ohm load.   10. Does a power amp improve sound quality? No, amplifiers don't improve sound quality. They just increase the signals to required levels. However if amplifiers have equaliser or other signal processing facility, they can make it sound different and possibly more suitable for listening pleasure. But again that is the work of signal processing part of amplifier.