Questions tagged [compensation]

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votes
3answers
3k 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
votes
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
278 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
votes
2answers
2k 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
720 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 ...
6
votes
1answer
910 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 ...
5
votes
3answers
4k 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 <...
4
votes
2answers
463 views

Why does overshooting occur when probe's adjustable capacitor is under-value

I can't wrap my head around how overshooting (the spike) happens when the 10X probe capacitor trimmer (Cp) is under-tuned (i.e. adjustable capacitor's value is not high enough). There are countless of ...
3
votes
4answers
499 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
5k 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
177 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
122 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
349 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 ...
3
votes
2answers
1k 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
votes
1answer
199 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
votes
3answers
845 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
840 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
567 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
712 views

Loop compensation of a Buck Converter

I have a buck converter. TPS54260 Vin = 7V-20V Vout = 5V Iload=600mA. I realise that there is a similar question in this forum but I was not able to get clarity. I want to understand what do you ...
2
votes
1answer
702 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
1answer
114 views

Do lead and lag filters have the behavior of high and low pass filters even if the zero and pole used are complex?

Consider the compensation transfer function \$\frac{s+z}{s+p}\$ so that the inequalities \$0<z<p\$ and \$0<p<z\$ correspond to lead and lag compensation respectively. At very low ...
2
votes
1answer
83 views

Offset problems with charge amplifier

I have a question about designing a charge amplifier. I am currently using this simple setup for my application. As input, I can use several commercial piezo-based accelerometers. I need a pretty ...
2
votes
1answer
880 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 ...
2
votes
1answer
914 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 ...
2
votes
2answers
985 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
244 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
228 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
1answer
133 views

Tilt compensation for yaw calculation from magnetometer and accelerometer

I am working on a project where i have to calculate the raw, pitch and yaw angle using an accelerometer and a magnetometer. I calculate the pitch and roll angle through the accelerometer and I am ...
2
votes
1answer
126 views

Microstrip blocking capacitor ground cutout — large cutout size

I'm attempting to minimize the \$S_{11}\$ of a \$10\,\text{pF}\$ DC blocking capacitor on a microstrip trace for my signal frequency range, which is \$5.3-5.9\,\text{GHz}\$. My microstrip trace width ...
2
votes
2answers
347 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
votes
1answer
528 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
vote
3answers
2k 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
3answers
443 views

Why is frequency compensation required here?

Circuit requirements: DC voltage gain: 50dB Unity gain bandwidth: 50MHz Phase margin: 45 deg(60 deg is recommended). The circuit is completely symmetric, so M1=M2, M3=M4, and M5=M6. Therefore the ...
1
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2answers
917 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
vote
3answers
5k 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
vote
2answers
56 views

Why is this buffered rail splitter oscillating and how can I compensate it?

Inspired by the question Op amp Power supply splitter with totem pole I played with the buffered rail splitter in LTspice. I placed a current sink as load on the output to simulate the current ...
1
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2answers
322 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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2answers
72 views

Compensation of custom high voltage power supply

To test an offline switching PSU I decided to build a custom isolated high voltage variable PSU. The idea was to build a nice, small, low power equivalent of a variac and isolation transformer that is ...
1
vote
1answer
757 views

How do we decide to use a lag compensation versus a PI compensation?

Although lag and PI compensation apparently have the same objective of improving the steady state response, how does one decide which one to use?
1
vote
1answer
307 views

Analog implementation of imaginary roots in a transfer function

I have a simple boost converter, and from multiple papers I've read through, a Type 3 Compensator is recommended. I designed one in Matlab/Simulink, and it reacts very quickly. The problem is, when I ...
1
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2answers
85 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
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1answer
408 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
86 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
vote
1answer
78 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
155 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
698 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
388 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
vote
1answer
40 views

Trouble with meeting design specifications of a second order system using Matlab

I am trying to solve the following question. Consider the transfer function $$G(s) = \frac{1.247}{s^2+9.76s+23.8}$$ is in the forward path of a unity feedback control loop. Assume that it is ...
1
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0answers
58 views

Underlying reasoning behind lead and lag nomenclature of compensation

If \$0<z, \;p\$, the Laplace transform transfer function \$\frac{s+z}{s+p}\$ constitute two distinct types of compensators. If we look at this schematic, \$0<z<p\$ (lead compensation) implies ...
1
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0answers
35 views

Phase Lag Compensator

I have a question on lag compensators in general. Why do they increase both the rise time and the settling time? Is it due to the introduction of a slow pole? Much thanks!