Questions tagged [compensation]

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3answers
2k views

Need for Temperature Compensation of Current Mirror

I am currently learning about current mirror configurations. I have made two of them so far. Both of them worked as desired but, when heated or cooled, the current through the right side (the side ...
8
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2answers
3k views

Why do we compensate PWM controllers?

I have been studying switch mode power supplies for a while. I have understood the working principle of several common topologies But there is a detail in the control circuit structures which I still ...
7
votes
1answer
238 views

Should I be concerned when loop gain rises back above 0dB on simulation?

Interim update Okay, I just realized I screwed up on the simulation. When I added \$C_{bp}\$ I upset the "break" in the feedback loop necessary to get the loop gain. The left-side lead has to go to ...
6
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2answers
1k views

Calculating values for compensation network (boost converter RC+C network)

I'm trying to build a boost converter with current mode PWM control, but I'm stuck at selecting capacitor and resistor values for compensation. I'm using a LT1619 as the controller IC: simulate this ...
6
votes
1answer
568 views

Interpreting bode plot of type 3 compensation network for buck regulator

I'm struggling to design the type 3 compensation network for a simple buck PWM controller. The controller is a Richtek RT8110B. According to the datasheet, half of the type 3 network is in-built and ...
5
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3answers
3k views

How to compensate gain and offset errors

I have an analog circuit which has an offset error as well as an gain error. I can measure the analog output of the circuit and I am able to manipulate the gain of the circuit by means of a factor <...
5
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1answer
779 views

Loop compensation design of buck converter

I am trying to design loop compensation with type-3 error amplifier for a buck converter. I'm a student and very inexperienced in this subject. Please bear with me. Here is the general procedure ...
3
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4answers
429 views

Control theory diagram for feedback circuit with compensation

An op-amp that drives a secondary gain stage might be given like this: simulate this circuit – Schematic created using CircuitLab Where it is important to note that FB1 is some impedence (...
3
votes
2answers
4k views

Temperature compensation in transistor current cource

I am working with analysis of BJT current source. I didn't get the explanation of temperature compensation in NPN transistor with PNP and pull up resistor. How does it work actually?
3
votes
1answer
123 views

Hybrid Boost-Flyback Stability Issue

I tried to design a step up SMPS to create ~200-300V from a 24V input with an expected power of ~12W max. Since the project is for a hobby, I chose to attempt a hybrid boost-flyback converter to get ...
3
votes
1answer
92 views

Compensation for op-amp difference circuit

I have a difference amplifier built with an op-amp (specifically, I'm using the LT6237) with 10dB gain: simulate this circuit – Schematic created using CircuitLab As it is, without external ...
3
votes
2answers
991 views

Finding transfer function of a compensator circuit similar to a type 2 compensator topology

I know how to find transfer functions of op-amp circuits using equations derived from using Kirchhoff's current law (nodal analysis), and normally I don't have any problems solving them. However, I ...
3
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1answer
99 views

Constant-gm bias circuit

I am doing a study on Improvements in biasing and compensation of CMOS opamp. Do you guys know how to come up with the equation for RDS4C ?
3
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3answers
676 views

Approximation of a Non Ideal Differentiator

simulate this circuit – Schematic created using CircuitLab The above circuit is a differentiator, the op amp is assumed to be a single pole op amp, that is \$ A=\frac{wt}{s}\$ The transfer ...
3
votes
1answer
553 views

Understanding in-loop compensation for capacitive-loaded OpAmp

I'm trying to understand the in-loop compensation for a simple amplifier loaded with a capacitive load, as seen in this article from Analog: http://www.analog.com/library/analogdialogue/archives/38-...
2
votes
2answers
463 views

Crystal compensation for temp and voltage

Introduction I'm toying with the design for a fail-safe wall clock controlled by multiple 32.768kHz crystal oscillators. I'm currently reading about compensation. Compensator from literature From ...
2
votes
1answer
669 views

Implementing an Avalanche Photo Diode Circuit

I am working on a circuit that will make low light measurements in the visible range. The measurements will be of biological samples that are fluorescing. For this application an Avalanche Photo Diode ...
2
votes
2answers
664 views

Compensated Attenuator question

In the explanation, it explains that C2, C3, C4 are for frequency compensating the impedance of C1 which varies according to frequency. Can someone explain how C2~C4 does it? and why the designer ...
2
votes
1answer
212 views

Oscillations in Precision Voltage to Current Converter Design

I am trying to re-design the TI Precision Design - Low Level (5uA) V-to-I Converter. My design goals are: Increase bandwidth from around 1kHz to 100kHz (ideally 1MHz in the future) Increase output ...
2
votes
1answer
207 views

Op-amp with compensation has positive feedback with over-unity gain

I am looking at the following figure (Maxim APPLICATION NOTE 5129 Stabilize Your Transimpedance Amplifier): I just can't understand the following: in the region half-way between fF and fi, the slope ...
2
votes
2answers
104 views

Emitter-coupled logic operation

For the operation of emitter-coupled logic and sedra smith book, 1) Compared to CMOS, why ECL is the faster logic family given that it requires so many transistors to propagate to output Y (T5 ...
2
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2answers
69 views

Frequency compensation and feedback capacitance

I was reading the chapter of Microelectronic Circuits (Sedra Smith) about negative feedback systems, and it shows an example of Miller frequency compensation with the capacitance Cf shown in the ...
2
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1answer
374 views

Average current mode control compensation

This is the structure of average current mode control (source here). Please look at signal \$V_{com}\$ at the positive input of PWM modulator. For proper operation, in steady state the magnitude of ...
1
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3answers
1k views

Wheatstone bridge offset

I have a Wheatstone bridge but I don't know the values of the resistances in it. My excitation voltage is 5 V. But instead of having 2.5 V on each output lines I get one line at 3.3 V and the other ...
1
vote
2answers
558 views

BJT vs OPAMP for RF signal amplification: BJT performs better, why?

I am working on developing RF wave generation from a DDS IC (AD9834-Analog device). The voltage we require as an RF signal is 6 times (3V peak to peak, sinusoidal, DDS output~=0.5V with supply to the ...
1
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3answers
4k views

Intuitive way to see pole/zero directly from schematic

The image below is the electrical configuration and the transfer function of a type II compensator using OTA. By looking at the transfer function, we can easily see that the circuit has two poles (...
1
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2answers
145 views

Compensation capacitor(s) in instrumentation amplifier

I wonder whether the discrete 3-opamp instrumentation amplifier requires any compensation capacitors: simulate this circuit – Schematic created using CircuitLab Is it in general recommended to ...
1
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1answer
621 views

Input Bias Compensation for a Comparator

I've been working on designing a discrete dual-slope ADC for school, and I've run into a problem. The schematic below shows my proposed input stage, an ideal integrator connected to a comparator. I've ...
1
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2answers
81 views

General process for compensating a complex system in the time domain

Say one has a system with feedback wrapping around some "complicated" system (more complicated than the traditional examples given): simulate this circuit – Schematic created using CircuitLab \...
1
vote
1answer
327 views

Compensation of forward voltage drop of a diode - software

In my case I would like to compensate with software a voltage drop over the diode. I have diode RS2J which supplies DC/DC (50mA - 200 mA) converter at this point with resistor divider I would like to ...
1
vote
1answer
77 views

Implementation of Adjustable Current Limiting Circuit

I have a circuit that can deliver 0-10V and 0-100mA to a load, and want to have an adjustable current limit that will limit the current delivered. To do this I have a current shunt that I monitor, and ...
1
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1answer
80 views

-20 db/decade Gain Slope requirement for Stability?

I have been learning Analog Filter designing. I started with Loop Compensation in power supply. I came across a document. It ...
1
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1answer
556 views

LM301 comparator and diodes on compensation

I'm trying to understand what's the purpose of the two diodes connected to the compensation pin (8), and what the output of the comparator is supposed to be. Also, I'd like to remove the 5V supply and ...
1
vote
1answer
310 views

Increase in compensation capacitor for op-amp

I am currently learning to design an op-amp, and understand that using compensation capacitors help to maintain stability of the op-amp. Currently, my compensation capacitor has a value around 10 pf. ...
1
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1answer
72 views

Stability of SMPS designed for a motherboard

Many books have covered the stability of many configurations of switch mode power supplies and they have given details on how to set the poles and the zeros of the compensator to make the the power ...
1
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0answers
46 views

Type 3 Compensation on Full Bridge DC-DC Converter with SG3525

I'm trying to build a 48V-400V full bridge dc-dc converter. I'm using sg3525 as pwm IC and trying to get isolated feedback from output and planing to do it with TL431. When I study on it people are ...
1
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0answers
32 views

Non Inverting Type 2 and 3 compensators

I'm looking for the topology and transfer function of a non-inverting type 2 and 3 compensators (PID controller). they are used in CC and CV feedback control in charging/Discharging circuits of ...
1
vote
1answer
468 views

Op-Amp's Dominant-Pole Compensation

I'm reading "Op Amps for everyone" (http://web.mit.edu/6.101/www/reference/op_amps_everyone.pdf) and I'm currently studying the chapter about the compensation of op.amps. but I'm missing a passage. At ...
1
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1answer
170 views

The Frequency Compensation of LT1683 in a DC-DC Converter

The fig. 10 of Jim Williams's article presents a 2A laser current source circuit using the LT1683. I am confused about the frequency compensation circuit of fig. 10 (pin 12 Vc of LT1683). The page 8 ...
1
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0answers
195 views

Using a suitable Compensator problem - Control Theory

Problem: \$\,\,\,\$ A system is described by the open loop transfer function $$\frac{k(s+2)(s+7)}{(s+5)(s^2+2s+5)}$$ Design a suitable compensator in order to have \$w_n =\sqrt{10}\,rad/s\$ and \$\...
0
votes
1answer
1k views

Intuitive to get pole and zero points for lead compensator

The circuit below is a lead compensator. I can easily know exact the pole and zero of the network by deriving the transfer function. However, I am wondering if there is an intuitive method to get the ...
0
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2answers
273 views

Transfer function of a real operational amplifer

We all know how operational amplifiers behave in real world. I am trying to figure out the transfer function of an operational amplifier, part number UA741CN, from the data sheet. The data sheet from ...
0
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1answer
157 views

Compensating Saturation Voltage of a transistor

simulate this circuit – Schematic created using CircuitLab I am working on this circuit, which is a voltage controlled oscillator. I am using the transistor as a switch in this circuit. The ...
0
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1answer
365 views

AD4610 - Is it possible to eleminate this single overshoot

I am trying to compensate input capacitance of the AD4610. It does not matter if it is actually over- or undershooting - there is always a spike: I do not have this problem with the OPA4141 for ...
0
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1answer
161 views

Type of capacitor for feedback / external compensation

Referring to the capacitor between the output and the inverting pin in an op-amp, in parallel with the feedback resistor --- should I use ceramic (NP0), or thin film? We're talking bandwidth in the ...
0
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1answer
68 views

How the effect of the output inductor is minimized and filter offers only single pole by current mode control?

In this application note "Switching Power Supply Topology Voltage Mode vs. Current Mode", page 2, Current Mode Control section the author claimed as follows: Since the Error Amplifier is now ...
0
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1answer
119 views

Adjustable non-inverting Buck-Boost converter failing right after starting in boost-mode

I am designing an adjustable non-inverting buck-boost converter based on LM5176 chip. Adjusting is done by DAC via feedback network, more on that technique can be found here. The input voltage is 32V ...
0
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1answer
202 views

DCDC converter load step and phase margin

When applying load step to a DCDC converter we can approximate the phase margin from the presence/absence of oscillation and the crossover frequency as well from the response time. The question is: ...
0
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1answer
63 views

Dynamic Compensator in Control Loop

Sorry if this has been asked previously, but I couldn't find anything here or elsewhere on Google (but maybe I'm searching the wrong terms). I'm trying to design a Type 2 compensator for a PWM chip I'...
0
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2answers
74 views

Why is this Type I compensator phase not 270 degrees?

This is a Type I compensator with a pole at origin. The transfer function between \$V_{in}\$ and \$V_{out}\$ is as follows: $$ \frac{V_{out}}{V_{in}}= -\frac{R_{2}}{R_{1}+R_{2}} \frac{1}{s (R_{1}|| ...