The Kynix Blog - Resistors

Ⅰ. IntroductionIn electronics, an operational amplifier is a circuit unit with a very high amplification factor. In the actual circuit, usually combined with the feedback network to form a certain functional module. It is an electronic device with a special coupling circuit and feedback. The output signal can be the result of mathematical operations such as addition, subtraction or differentiation, integration, etc, thus it was used in analog computers to implement mathematical operations.CatalogⅠ. IntroductionⅡ. Non-inverting Amplifiers and Inverting Amplifiers   2.1 Terminology   2.2 Non-inverting Amplifier Circuit   2.3 Inverting Amplifier CircuitⅢ. Note: Input ImpedanceⅣ. Amplifier GainⅤ. Differences between Inverting & Non-Inverting Amplifiers   5.1 Facts Consideration   5.2 Differences SummaryⅥ One Question Related to Amplifier and Going Further   6.1 Question   6.2 AnswerAn op amp is a functional unit that can be implemented in discrete devices or in semiconductor chips. With the development of semiconductor technology, most of the op amps exist in the form of a single chip, but there are many types of op amps, which are widely used in the electronics industry. The op amp can be simply viewed as a high-gain direct-coupled voltage amplifying unit with one signal output port (Out) and two high-impedance inputs, non-inverting input and inverting input, so op amps can be used to make the non-inverting, inverting, and differential amplifiers.Difference between Inverting and Noninverting Amplifier Ⅱ. Non-inverting Amplifiers and Inverting Amplifiers2.1 TerminologyAn operational amplifier in an electronic circuit has a non-inverting input and an inverting input. The same polarity of the input and the output is a non-inverting amplifier, on the contrary, it is an inverting amplifier. And the inverting amplifier circuit has a function of amplifying the input signal and inverting the output. 2.2 Non-inverting Amplifier CircuitWhen a positive phase is received, a positive phase is output, whereas the negative phase is output. The phases of non-inverting end and the output end are the same. In other words, the signal is applied to the non-inverting input of the op-amp, and it is not inverted at the output when compared to the input. Figure 1. Non-inverting Amplifier(A signal applied keeps its polarity at the output, and a positive input remains a positive output.)Vin and V-Virtual are short circuit in the figure, where Vin=V-……aBecause of the virtual open circuit, there is no current to the inverting input, the current through R1 and R2 is equal, and the current is set to I, which is obtained by Ohm's law:I=Vout/(R1+R2)……bVin equal to the partial voltage on R2, where Vin=I*R2……cBy a, b, c, where Vout=Vin*(R1+R2)/R2 2.3 Inverting Amplifier CircuitWhen the positive phase is received, the negative phase is output, whereas the positive phase is output. And the non-inverting end and the output end are keeping inverting relation. An inverting amplifier provides the same function as the common emitter and common-source amplifier.Figure 2: The grounding of the op amp is 0V, the inverting end and the non-inverting end are short circuit, so it is also 0V. The input resistance of the inverting input is very high, while it is virtual open. So that there is almost no current injection and outflow, then R1 and R2 are equal to a series connection, the current flowing through each of the components in a series circuit is the same, that is, the current flowing through R1 and the current flowing through R2 are the same. Figure 2. Inverting Amplifier(The polarity of a signal is reversed at the output, and a negative input becomes a positive output.)Current flowing through R1: I1=(Vin-V-)/R1………aCurrent flowing through R2: I2=(V--Vout)/R2……bV-=V+=0………………cI1=I2……………………dBy solving the above algebra equation, we can get the result:Vout=(-R2/R1)*ViThe inverting amplifier circuit has the function of amplifying the input signal and inverting output, which is a negative feedback technique. Negative feedback returns a portion of the output signal to the input. The reason why the inverting amplifier can only connect the signal to the inverting input is because the negative feedback can be formed only in this way, otherwise it will not work in the linear amplification region.When inputting from both ends simultaneously, the size and phase are the same, that is the common mode signal, and the theoretical output is zero. Ⅲ. Note:  Input ImpedanceThe input impedance of the non-inverting input is high, and the input impedance of the inverting input is low. The input impedance of the non-inverting input is basically determined by the bias resistor connected in parallel with the non-inverting terminal, and the resistance can be very large. When the inverting input is connected, the feedback resistor is connected between the inverting terminal and the output terminal, and the resistance is small, so the input impedance of the inverting input is relatively low.1. The magnitude of the input resistance of the non-inverting amplifier does not affect the input impedance, and the inverting amplifier input resistance is approximately equal to the input impedance.2. When the input impedance is required to be high, the non-inverting amplifier should be selected.3. If the input impedance is not required to be large, the non-inverting or inverting can be selected at this time. When the phase is not considered strictly, the inverting amplification is preferred because it only has the differential mode signal.4. The CMRR of the inverting amplifier is better when the CMRR is decisive.Inverting amplifier, the input common mode of the op amp is almost constant, the common mode amplification is not reflected to the output, and the input common mode of the op amp in the non-inverting amplifier changes with the input signal, the common mode amplification of the op amp will be reflected Output. Therefore, the CMRR of the inverting amplifier is better when the CMRR of the op amp is decisive. Ⅳ. Amplifier GainBasic Inverting Amplifier Made with an Op-ampNon-inverting AmplifierInverting AmplifierGAIN (AV) = 1+(R2 / R1)Example:if R2 is 1000 kilo-ohm and R1 is 100 kilo-ohm the gain would be :1+ (1000/100) = 1 + 10 or GAIN (AV) = 11If the input voltage is 0.5v the output voltage would be : 0.5 X 11 = 5.5vGAIN (AV) = -R2 / R1Example:if R2 is 100 kilo-ohm and R1 is 10 kilo-ohm the gain would be :-100 / 10 = -10 (Gain AV)If the input voltage is 0.5v the output voltage would be : 0.5v X -10 = -5v Ⅴ. Differences between Inverting & Non-Inverting Amplifiers5.1 Facts ConsiderationIt can be seen that comparing them is from the following aspects: input and output impedance, common mode anti-interference.1. The input impedance of the non-inverting amplifier is equal to the input impedance of the op amp, and they are close to infinity. The input resistance of the non-inverting amplifier does not affect the input impedance; and the input impedance of the inverting amplifier is equal to the resistance of the series resistor of the signal to the input. Therefore, when the input impedance is required to be high, the non-inverting amplifier should be selected.2. The input signal range of the non-inverting amplifier is limited by the op amp's common-mode input voltage range, while it is not the case with the inverting amplifier. Therefore, if the input impedance is required to be low and the phase is free, the inverting amplification is preferred because it only has a differential mode signal. And the anti-interference ability is strong, thus a larger input signal range can be obtained.3. In the design where the same magnification is required, try to select a resistor with a small value, which can reduce the influence of the input bias current and the influence of the distributed capacitance. If you are more concerned about power consumption, you have to compromise on the resistance.4. Determine if an input signal is a non-inverting input or an inverting input. If the input resistance of the amplifier circuit is required to be large, the non-inverting input amplifier circuit should be used because the increase of the input resistance of the amplifier circuit will affect the voltage gain. When the inverting input resistance is increased, the voltage gain of the circuit is reduced, and the voltage gain is also affected by the internal resistance of the signal source. Therefore, when designing the inverting input amplifying circuit, sometimes the input resistance and the voltage gain is difficult to balance. If the bias resistor or the voltage divider is appropriately increased, the input resistance of the amplifier circuit can be increased, and the voltage gain has little or no effect on the voltage gain, which requires a better understanding of the circuit.Figure 3. Integrated Circuit Using Op-amp5.2 Differences SummaryThe integrated amplifier can be connected to the non-inverting or to the inverting amplifier. Is it better to select non-inverting amplification or inverting amplification? Let's look at the difference between them.1）non-inverting amplifiera. AdvantagesThe input impedance is equal to the input impedance of the op amp, which close to infinity.b. DisadvantagesThe amplifying circuit has no virtual ground, so it has a large common mode voltage, and the anti-interference ability is relatively poor. So that the op amp requires a higher common mode rejection ratio, and another disadvantage is that the amplification factor can only be greater than one.2）inverting amplifiera. Advantages The potential of the two input terminals is always approximately zero (the non-inverting terminal is grounded, and the inverting terminal is virtual-grounded), in addition, only the differential mode signal exists, and the device has strong anti-interference ability.b. Disadvantages The input impedance is small, which is equal to the resistance of the series resistance of the signal to the input.3) The gain calculation of the two are different, and their phases are opposite. Ⅵ One Question Related to Amplifier and Going Further6.1 QuestionWhat are non-inverting amplifiers used for?6.2 AnswerThe non-inverting amplifier configuration is one of the most popular and widely used forms of op amp circuit and it is used in many electronic devices. The op amp non-inverting amplifying circuit provides a high input impedance along with all the advantages gained from using an op amp. Frequently Asked Questions about Difference between Inverting and Noninverting Op Amp1. Which is better inverting or noninverting amplifier?Inverting op-amps provide more stability to the system than non-inverting op-amp.In case of inverting op-amp negative feedback is used that is always desirable for a stable system. 2. What are the advantages of non inverting amplifier over inverting amplifier?The advantages of the non-inverting amplifier are as follows: The output signal is obtained without phase inversion. In comparison to the impedance value of the input at the inverting amplifier is high in the non-inverting amplifier. The voltage gain in this amplifier is variable. 3. What is an inverting amplifier used for?The inverting amplifier is an important circuit configuration using op-amps and it uses a negative feedback connection. An inverting amplifier, like the name suggests, inverts the input signal as wells as amplifies it. 4. Where are non-inverting amplifiers used?The non-inverting amplifier configuration is one of the most popular and widely used forms of operational amplifier circuit and it is used in many electronic devices. The op amp non-inverting amplifier circuit provides a high input impedance along with all the advantages gained from using an operational amplifier. 5. Why are inverting amplifiers better than non inverting?Inverting op-amps provide more stability to the system than non-inverting op-amp.In case of inverting op-amp negative feedback is used that is always desirable for a stable system.

A team of MIT engineers has described a novel way of controlling the flow of water in flexible tubes, a finding with implications for agricultural systems worldwide. Their research, published in the Journal of Mechanical Design, could reduce the energy demands of pulsating sprinklers used for irrigation."Food and its relationship to water is one of the biggest problems in the world," says Ruo-Qian Wang, a former postdoc at the MIT Tata Center for Technology and Design who is now a postdoc at the University of California at Berkeley. "There is a clear need for efficient irrigation technologies that save money and conserve resources."Wang co-authored the paper with three researchers in MIT's Department of Mechanical Engineering: graduate student Teresa Lin, PhD candidate and Tata Fellow Pulkit Shamshery, and Assistant Professor Amos Winter.The model they propose could be especially useful in developing countries, where many farmers cultivate small plots of land without reliable access to the electricity grid. These farmers rely on solar or diesel power to draw water for irrigation."If you bring down the energy requirements of the irrigation system, that means a farmer can buy a smaller solar panel, or use less diesel," Wang says. "Everything gets cheaper and more accessible."Compensating for pressureThe researchers focused on a device called a Starling resistor, which is a flexible tube that collapses as pressure is applied. This device is noted for its similarities to human respiration, and has been used to model flow in the lungs and airways."But," Wang says, "it has never been applied to a pressure-compensated flow control system for agriculture."The team created an experimental Starling resistor architecture that introduces a needle valve, which allows for independent control of two key variables: activation pressure and flow rate. The goal is a phenomenon called pressure compensation, in which a steady flow rate can be maintained no matter the pressure differential."Activation pressure is key to energy consumption," Wang says. "A traditional resistor has to achieve a high level of activation pressure, about 1 bar, to activate the pressure compensation mechanism. That takes a lot of pumping power."The team's experiment showed that using a rubber tube to replace the diaphragm of the existing Starling resistor design can reduce the needed activation pressure by 90 percent."As a result, Wang says, "farmers can use smaller pumps and smaller solar panels to provide the activation pressure."They placed the needle valve at a critical juncture in the system, where, together with the rubber tube, it acted as part of a series of resistors to water flow. Using different tube lengths and thicknesses, they discovered that adjusting the needle valve changed the flow rate, but did not change the minimum pressure needed to "activate" the system. Their paper describes the first mathematical model that quantitatively predicts this decoupling of the two variables.This means their device could make it easier to optimize irrigation systems for a variety of settings."We can design the activation pressure using a given tube material and geometry, and by adjusting the needle valve, water can be applied to different crops at different flow rates," Wang says.This new Starling resistor can be optimized for a high flow rate—necessary for pulsating sprinklers—while the pressure compensation phenomenon also causes the tube to oscillate, which gives it a natural pulsating quality.Wang explains that "a traditional sprinkler uses a spring-loaded arm to impact the flow rate. That wastes energy, and energy has a cost. This device provides pulsation by itself."Leveraging global expertiseThe project has grown out of the team's partnership with Jain Irrigation Systems, a multinational company headquartered in Jalgaon, India, that provided funding, technical knowledge, and market expertise. Researchers in Winter's GEAR Lab have collaborated with Jain on a number of projects related to water and agriculture."Jain is a $1 billion revenue company with small-scale farmers comprising 80-90 percent of their clients," says Wang. "They can commercialize agriculture projects in that space better than any other company."He notes that Jain's guidance and ability to field-test prototypes helped keep the Starling resistor project on the right track."Being able to test this architecture with Jain helped us determine that it had potential in sprinkler systems. Now we have a great opportunity for our work to make an impact."Reference:KY83-TFH85M51R0JEKY83-PF2472-100RF1KY83-P8212 

TT Electronics launched the LCS series of thin film resistors. For sensing and measurement of DC and AC currents in the sub-3A range, the resistors bring precision thin film resistor performance into the field of low ohmic values for use in very accurate current sensing applications. Most thin film chips have a minimum value in the range of one to 10Ω, but TT Electronics’ LCS series uses a proprietary technology to extend this down to 100mΩ.The resistors also feature low sensitivity to temperature variations.Aimed at designers of power supplies, battery monitoring, process control and point of load converters, the LCS resistors will find acceptance for use in market sectors such as industrial, medical, instrumentation and IT.The resistors offer a level of precision of ±0.5% and ±50ppm/°C, providing higher precision and temperature stability of current measurement. While there are currently a few thin film chip products below one ohm that use the nickel phosphorus material traditionally used for low value films, TT Electronics’ proprietary LCS film system delivers lower TCRs (temperature coefficient of resistance) in the hundreds of milliohms range.Available in five sizes from 0603 to 2512, LCS resistors feature high power ratings, e.g. 1W for 2512, which is comparable to thick film ratings. This also enables smaller footprints to be used. Enhancing reliability and reducing field failures in industrial applications, LCS also feature anti-sulphur terminations.A major factor driving the demand for this type of product is the growth of battery powered equipment. The proprietary thin film technology of TT Electronics’ LCS bridges the gap between the ohmic values offered by bulk metal chips and those of conventional nichrome thin film chips. Whilst thick film chips are also available in this very low ohmic range, LCS offers superior precision, offering the lowest TCR for precision current sensing available in the 0.1 to 1 Ω range.Reference:KY83-ERA-S15J180VKY83-ERA-S15J472VKY83-ERA-S27J182V 

Riedon has today announced a cost-effective power resistor design achieving superior performance in high-frequency applications and high-speed pulse circuits. The various TO-style resistors within Riedon’s PF family are non-inductive and use an advanced power film formed on a heat-conducting alumina substrate that is metalized and soldered to a heat-dissipating copper plate tab.This process offers devices featuring excellent thermal resistance in small-size, thin-profile TO-style packages for high-density applications.Phil Ebbert, Riedon’s VP of Engineering, commented: “All our TO-style thin-film resistors combine superior performance with the full power-dissipation capabilities these packages offer. In addition, the low-inductance design makes these parts ideal for high frequency applications, such as wireless communications, or in systems that need to withstand short-duration, high-energy pulses, for example, medical equipment.”Available with power ratings from a few Watts up to 600 Watts, the resistors come in both through-hole and surface mounting packages. The PF1260 series provides resistances in the range 0.01Ω to 51kΩ, tolerances from ±1%, a temperature coefficient from ±50ppm, and up to 20W dissipation (with a heatsink) in an epoxy-molded TO-126 leaded package. The PF2200 and PF2470 series offer similar specifications but with increased dissipation up to 50W and 140W in leaded TO-220 and TO-247 packages, respectively.Designed for ultimate power dissipation, the PF2270 series handles up to 300W in a screw-terminal TO227 style package, when attached to an appropriate heatsink and subject to temperature derating. The last of the new introductions, the PFS35 series provides a solution for surface mounting, using a TO-263 housing (D-Pak) to provide 35W dissipation when used with a heatsink or 2W with a simple solder pad.Riedon’s full range of TO-style power resistors are available from Kynix.Reference:PF22000T12BKPF22000T12LGPF22000T12BK230PF22000T12LG230