Questions tagged [compensation]
For questions about designing electronics to account for undesirable characteristics or behaviors, such as frequency compensation in a feedback control system to avoid instability and/or improve gain and phase margin, reduce overshoot and ringing, improve bandwidth, etc. Consider using in conjunction with associated tags such as "feedback", "stability", "frequency-response", "nyquist-plot", "bode-plot", "operational-amplifier", etc., if appropriate.
157 questions
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How to measure the 3 dB bandwidth of an opamp in LTSpice
I am interested to use an opamp with an exact 3 dB rolloff at 320 kHz
for an sinewave (voltage swing) from -10 to +10 V.
I think I need to do this using some resistors and capacitors on the feedback ...
- 815
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2
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128
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Reason to use a current loop in addition to a voltage loop in linear regulators
I recently came across this figure detailing the compensation of the UC3833 in the App Note “A High Performance Linear Regulator For Low Dropout Applications” Available here and they show the use of ...
- 1,616
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118
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Buck-boost output drops when loaded
The LTC3566, a PMIC intended for battery and USB supplied applications, integrates a battery charger, a power path and a buck-boost converter. For my board, I copy-pasted the schematic found on the ...
- 179
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1
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138
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Op amp GBW compensation when used in MFB filter
I've been reading through this app note by TI where its proposed that when using a MFB filter a compensation resistor can be added to overcome limitations of lower GBW op amps. I've been working ...
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0
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65
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Buck-Boost fault mode on startup and gradual current decrease
I am using the TPS92692 in buck-boost mode with an analog signal to set Iadj and PWM. When I start the circuit, it consistently goes into fault mode and the fault pin is periodically set low. However, ...
- 83
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2
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130
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Analog Compensator Vs digital Compensator in Power electronics Converter
I was working on designing a feedback compensator for my buck converter. I decided to use the compensator circuit in the feedback and give its output to Arduino which gives the duty cycle as shown ...
- 693
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48
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Feedback compensation on a buck-boost led driver
I tried to calculate the compensation network for a TPS92692 in buck-boost topology and I can't find the same value for the typical buck-boost led driver (page 41 of datasheet).
Section 9.2.2.2.12 ...
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65
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Movement Sensor circuit
I have this PIR sensor circuit, can someone explain what each of the capacitors do in the circuit?
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163
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Stability issue: Compensation changes using Bode plot in LTspice
I am encountering issues with a LT8390 design, particularly in higher load current conditions, which leads me to suspect a stability problem. The design parameters are as follows: vin 18-36 (28v ...
- 534
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0
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46
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Thermal EMF on shunts
I tested the accuracy of a shunt resistor of 20 μΩ by applying short pulses of 100 A. At lower current levels near 0, I noticed the sensed current had a variation of ±300 mA. I did some research and ...
- 15
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1
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348
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Op-amp - Lead compensator design
I would be very happy if anyone can help me find answer regarding to questions below:
The lead compensator is added to the system to increase the phase margin.
1'st picture is related to the ...
- 730
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4
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What is the purpose of including (or excluding) the output resistor in the feedback loop of an op-amp buffer?
I have often seen (and made) circuits like this. It is a simple inverting op-amp buffer, plus a small current-limiting output resistor to protect the the op-amp if the output is shorted.
simulate ...
- 243
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2
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724
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What is the purpose of compensation resistor in the CMOS Two stage op-amp circuit shown here? And it effect on Unity Gain?
I wonder why there is a compensation resistor in some CMOS Op-Amp circuit shown here. What is the purpose of this? I tried to vary it and this is what I got for unity gain of each value. Based on many ...
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207
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Minimum compensation capacitance for 45 degree phase margin in two-stage CMOS OTA
I'm working through a solved example problem on compensation of a two-stage op amp. For extra context, this example problem is originally from an exam of a now-concluded course offering, so it is ...
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188
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LTC7803 Buck Converter Current Mode Compensation
I wanted to design a step-down converter using the LTC7803. Goal is to have a 5V, 0-2A output with an input voltage range of 10-30V. Switching frequency is set at 1MHz. As shown in the LTSpice picture ...
- 101
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2
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632
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Buck Converter Compensation and Transient Response
I am trying to compensate a buck converter. I've set up an averaged model of a buck converter in LTSpice.
Here is a picture of the simulation. The B3 voltage takes into account the gain from using a 5 ...
- 101
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1
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82
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Current regulation compensation SG3524 and right place to place sense resistor
What is the right place to place current sense resistor? As in picture we get traingular wave n position 1, sine wave with highest amplitude on pos 2, smaller sine wave on pos 3 and nearly flat line ...
- 135
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0
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155
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Battery charger circuit confusion - drive and compensation
I'm building something that is going to have Li-Ion batteries so I'm trying to learn how a battery charger actually works. I've been looking over the datasheets for the BQ2000 and the BQ2954. I will ...
- 349
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2
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333
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How feedback loop is done in wide voltage range laboratory power supply? TL494 compensation
Hello i would like to ask how is compensation done on switching PSU with wide range variable output voltage (from zero to several hundres of volts). I have succesfuly (I guess) simulate my own design ...
- 135
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0
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75
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Boost PFC compensator design
I'm trying to design a type II compensator for my LT1249 boost PFC stage but I'm not sure on how to place the zero and poles frequencies using a typical error amplifier:
I have a working LTspice ...
- 388
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1
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289
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Compensator design for control systems
Currently, I'm working on linear control course from Nise's book. In the root-locus design chapter, some methods were explained for lag and lead compensator design which uses root-locus properties. ...
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716
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DC-DC converter error amplifier output
I am new to DC-DC converter electronics. I was wondering what the output of the error amplifier/compensator looks like.
Is the output of the compensator being driven to the Vref value set on the non-...
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0
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606
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Trying to perform transient frequency response with LTspice or Microcap, TL494 compensation
I have tried to do Bode plot of my uncompensated plant by myself in LTspice 17.1, but the result looks strange to me. This topic is a follow-on to this one.. I have no clue why it comes with 290 ...
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TL494 compensation
I am trying to make a homebrew power supply. It works at the moment, but compensation is not done yet.
Can someone help me to calculate and select the right poles and zeros? VCM is at error op-amp 1, ...
- 135
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0
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187
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AC analysis of SMPS shows instability. How to modify the analysis to reflect the transient stability?
Background
I have designed a switch-mode power stage with voltage-mode control that uses an LCLC filter in its output to obtain a very low ripple output voltage.
I have empirically arrived at a ...
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140
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Cancelling optocoupler pole in an isolated voltage mode controlled smps
I am designing a 600W halfbridge converter with a voltage mode controller(TL494). I am using a type 3 compensator with TL431 as shown in the image below:
where:
The capacitor C2 constitutes the ...
- 101
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1
answer
104
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DCDC booster oscillation because of small drops of input voltage
I'm stuck with this DCDC booster design that shows a bad oscillation output when a little voltage drop is present at the input.
I have already tried to change the inductance to 4.7uH (actually, the ...
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2
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129
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How to drive 400 nF load with DAC
I need to drive a some kind of pzt transducer with a triangular 6 Vpp voltage. The transducer is modeled as a 400 nF capacitor. I want to drive it with 10 kHz 3-9 V triangular voltage however my DAC ...
- 161
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2
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44
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Double pole, double zero: incorrect plot?
I can't seem to find where I'm going wrong here. Suppose I want a double pole, double zero system that looks like this:
$$ \dfrac{\left(1+\dfrac{s}{\omega_z}\right)\left(1+\dfrac{s}{\omega_z}\right)}{\...
- 430
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1
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86
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Current control loop compensation network
I have an application that uses n-channel Mosfet as a high-side switch controlled by an IC driver. The point of the Mosfet is to manage the inrush current to the load. I understand that the resistor ...
- 23
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1
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161
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Controller for boost converter
I'm trying to design a controller for a boost converter by the "shaping loop gain" method as in the Fundamentals of Power Electronics textbook by Ericson and Maksimovic.
I see that there is ...
- 430
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1
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236
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Why is it easier to make a boost converter stable by feeding back a very small amount of output?
The image below is about peak current mode control for a boost converter. Someone said that it's easier to make it stable by feedback a very small of output like 1/10 Vout (or R2 << R1). ...
- 698
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537
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Role of input capacitance for cascode-input op-amp
In the below schematic of a cascode-input op-amp, the input transistors M1 and M2 present no capacitive load to the input signals, because their gate-source and gate-drain voltages are stabilized. The ...
- 23.4k
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Output voltage not stable - What is compensation with respect to DC-DC (buck converter)?
EDITS:
Input voltage range: 24V to 48V.
Changing the load current from 0.38A to 1.018A increases the mean output voltage from 12.779V to 13.26V. The supply should be producing 12.5V.
I'm using this ...
user220456
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Need help understanding error amplifier compensation
This application note (for the PWM controller I am using, UC3825B) details about error amplifier compensation for the built-in error amplifier.
It says it will be compensated to cross 0 dB at (...
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1
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Type-2 compensator transient response
I'm looking to find the transient response to a step impulse of a type-2 compensator.
I already found the transfer function, but when it comes to finding the transient response by using the inverse ...
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1
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136
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Why are there two different feedbacks in this battery simulator design?
I am trying to understand this LT1970 Battery Simulator Design and I could not figure out what is the point of two different feedback legs in this circuit? I have tried AC analysis but could not get ...
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1
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243
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Can I replace the ceramic capacitor with tantalum?
In the following topology, a 2200nF multilayer ceramic capacitor (SR305E225MAR) is used in the compensation network. Can I replace it with a tantalum capacitor with equivalent voltage and capacitance? ...
- 755
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2
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246
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14-Volt 6-Amp Power Supply Stability
Design Requirements:
The purpose is a linear DC power supply for 12-volt aircraft, marine, and amateur radio equipment
power source 20 volts @ +/-10%. (output 85W = 6A*14.2V)
Rser on V1 = 0.4 or ...
- 1,158
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2
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366
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LTspice-RIAA-simulation not working out
I'm trying to simulate a RIAA-phonograph-preamp since I want to build a phono-preamp. I've built everything according to the data provided by LT for the LT1115. But my simulation seems to not be ...
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2
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How can gain and phase margin be used to assess stability of SMPCs as for most of the cases (except buck), they always have a Right Hand Zero?
I was going through this Operational Amplifiers, Theory and Practice by James Roberge. On Page 146, it is mentioned that for systems that have negative feedback at low or mid frequencies and that have ...
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Integral Compensator Realization from Transfer Function
I am trying to design a compensator based on the transfer function below
Gc(s)=(1.017E6s+4.969E9)/(s^2+4.884E5s)
The transfer function has a constant that is offsetting circuit gain, followed by a low ...
- 13
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2
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335
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Tricking feedback of a buck converter
I need to trick the buck converter feedback. The converter that I am going to use is TPS40192DRCT.
Instead of the regular resistor divider, I want to feed there voltage proportional to current ...
- 1,395
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1
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283
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Phase Margin and Transient Response Contradicting?
I am designing a forward converter that is supposed to work as a pre-regulator for a linear supply. The forward converter is supposed to be able to give output from 4V to 34V and 0 to 5A. While ...
- 180
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1
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309
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Why this overshoot in transient?
I am designing a forward converter whose output can be variable from 4V to 30V, 0-5A. This is going to be a pre-regulator for a linear converter. This is the schematic:
I am using UC3844 controller ...
- 180
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0
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621
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Using UC3844 and TL431 to compensate a forward converter
I am designing a forward converter capable of providing 5A at 30V at the output. For the compensation part, I am thinking to use UC3844 in combination with TL431 to achieve peak current mode control.
...
- 180
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0
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118
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How to plot uncomensated loop gain in LTspice
I want to plot an uncompensated loop gain of a dcm flyback dc-dc converter. I know that I can derive the control to output transfer function and then plot the uncompensated loop gain but that just ...
- 180
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What is the better way to stabilize this discrete op-amp and why?
I have the following simple op-amp circuit, which is meant to drive a MOSFET (M1) gate and work as a voltage regulator. It is discrete for a mix of reasons (necessary bandwidth, using existing BOM ...
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1
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107
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Feedback loop design (buck converter): Output capacitance- effective value or nominal value to be considered?
In this TI datasheet of TPS62180, it was mentioned that the LC filter combination should be selected from a set of predefined values. I understand this is usually the case for an internally ...
- 3,156
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3
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834
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Problem stabilizing this PMOS LDO
I am considering a discrete LDO for a supply rail that needs ~\$m\Omega\$ impedance at 10 kHz.
While the following circuit does what I need (according to Spice), it becomes unstable if C2 is smaller ...
- 23.4k