# Questions tagged [feedback]

Feedback is a process whereby information from an output of a signal is used (intentionally or unintentionally) to alter the input of the same signal. Commonly used in operational amplifiers. An everyday example is the high-pitched audio frequency heard when a microphone picks up audio from its own amplified output.

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36 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 ...
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### Discrete-Time versus Continuous Time analysis of feedback system

Imagine a generic feedback system, where A is forward gain and F is feedback gain. I will now go over two cases where in i will analyse this system. 1. Reference = 110, A=10, F=1 In this case, it ...
55 views

### NCP1117 Regulator voltage feedback not working correctly

I'm having a brain fart. Reading 3.1V ish on the output. My +5V0 net is after a schottky diode with 5V + a little bit coming from the NCP1117, and another 5V0 coming from a USB connector. Reason being ...
20 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 ...
52 views

### Simple Stability and Feedback

I have a question, my book says that for the system in this picture: If the system has G(s)*H(s) with a module of 1 (0dB) and a phase of -180°, the system is in Simple Stability, so it is like in ...
137 views

### Closed Loop System

Why is RC circuit considered closed loop system with negative feedback? Is it because it has a differential equation due to which current 'I' through capacitor 'C' will be C*(dVo/dt) = C*{Vo(t)-Vo(t-h)...
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### What is the range of feedback resistors of LM2577 adjustable version?

I am making custom boost converter with LM2577 adjustable version. I have a question about selecting feedback resistors R1 and R2 For R1 and R2 formulas available in the datasheet, but they do not ...
32 views

### The difference in connecting the FB LM2596 before or after the output capacitor

There is a step-down converter (12V / 5V) based on the LM2596. It has a voltage regulation function based on a tuning resistor. There should be feedback at the controller output (FB line) In my ...
58 views

### Introducing SiPM Array to an Op-Amp

I'm working on a transimpedance amplifier circuit, but it appears that there are issues reading out a signal. The source is comprised of sixteen individual SiPMs in parallel with each other, ...
105 views

### Positive and negative feedback in opamp in same circuit

In our class we encountered several opamp circuits, for example, Non-inverting integrator: simulate this circuit – Schematic created using CircuitLab or we can consider the sallen-key type ...
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### Beginner's power supply design

I'm trying to design a bench power supply that can be easily controlled by a microcontroller and is more efficient than a simple linear design (although crazy-high efficiency is not the primary target)...
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### Transimpedance Amplifier Gain Analysis

I'm trying to go through a mathematical gain analysis of a closed-loop transimpedance amplifier circuit, but I'm having issues trying to relate the block diagram to the actual circuit. simulate this ...
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### How do I convert a PWM signal (with a specific duty cycle) to its respective Analog value, for an application in a low voltage,high current circuit?

I wanted a 16V,50A regulated power supply but could not find it in the market. I also searched for a buck converter for the same current output and could not find anything. So I thought of making it ...
67 views

### OpAmp resistor to ground in feedback loop

I am currently tasked with improving the design of an electrometer unit. It was NOT designed by an electrical, and there are some questionable design practices. My question is concerning the first ...
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### Op - Amp: Linearity, Negative Feedback and Virtual Short

I need some explanations about Linearity, Negative Feedback and Virtual Short for an ideal Operational Amplifier. Precisely, I have been always told that an operational amplifier with negative ...
103 views

### Help identifying component in SMPS

I have been working on a Schroff/Cherokee Europe PE1947/23B SMPS (circa 2004?) and have had trouble identifying a component within the circuit. This SMPS features the following outputs: +12v DC @ 8A ...
83 views

### Question about the slew rate

Let's consider an op-amp: From basic courses of electronics, we know that the output voltage as a function of the differential input is given by the following picture: Now, assuming that: the op-...
25 views

### Question about a common mode feedback circuit

I'm studying fully differential op-amps. I know from the theory that with fully differential op-amps, unlike the single-ended op-amp, the output common mode is not stable because of unavoidable ...
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### Question about the common mode

After introducing the two-stages op-amp and frequency compensation for this circuit, during lecture the Professor asked us to find as an exercise a possible polarization of the following circuit: in ...
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### Question about feedback in a current reference

I'm studying the following Vbe-based current reference: The author of my book says: Observe that the circuit has two feedback paths around the gain stage. One positive, the other negative. ...
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### Unity Gain Buffer Initial Conditions

simulate this circuit – Schematic created using CircuitLab A typical way of analysing the unity gain buffer is: Where A is Open Loop Gain Vout = A(Vin - Vp) and Vp = Vout therefore ...
32 views

### Design Bootstrap Follower

I got confused in the emitter follower circuit with tracking feedback (bootstrap). The mechanism of operation is understandable, but how do I choose the resistor values ​​correctly and optimally? For ...
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### Nonlinear Observer Question for BLDC

I'm looking at the article posted here, and I'm trying to figure out what it is that they're controlling and how. Specifically, Dave Wilson from TI gave a presentation called "Teaching Old Motors New ...
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### Logic inverter feedback resistor, SPDIF Input/Ouput circuit

What purpose of these resistors? Spdif level about 0.5Vpp. Do I need use feedback resistor if I will convert 3.3V SPDIF to 5V? I want to make 4-way SPDIF Input/Output for WM8805 I2S<>SPDIF ...
108 views

### I set up an amplifier (LF351) for a gain of 5.7, but it is saturating. Do I have to utilize the offset null pins?

simulate this circuit – Schematic created using CircuitLab The feedback network I am using is a voltage divider with 4.7K and a 1K resistor. The node after the 4.7K resistor is connected to the ...
58 views

### About the differential gain [duplicate]

Let's consider any circuit which contains a differential pair, for example a telescopic cascode single stage OTA: In every circuit like this one, my professor and every book compute the small signal ...
54 views

### Negative Feedback Factor

As of now most of the negative feedback systems I have encountered have a feedback factor that is less than 1 but positive. However in some situations it seems the system can behave as positive ...
96 views

### Question about differential signals and feedback

Let's consider, for example, this circuit: During lessons, our professor always assumed perfect differential input (two signals with the same dc value and with equal and opposite amplitudes). As a ...
108 views

### Changing output voltage of a buck converter by electronically swapping the feedback resistors

I am going to design a circuit which is going to output some digital signals. The output stage of the circuit will have some level shifters. The level shifters will give flexibility to the user to ...
39 views

### feedback loop component dc converter

Consider the schematics below, the switching frequency is 250KHz, So, The cross over frequency be 250/5 = 50KHz. My ADC is able to sample at 1MS/s which is good as from the SNR perspective.Now, the ...
112 views

### Op-amp input impedance

I was reading the following tutorial from Analog Devices: https://www.analog.com/media/en/training-seminars/tutorials/MT-040.pdf They include the following image and state: In most op amp ...
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### How to select resistance to cancel offset output voltage due to bias current?

Consider the figure above how Rcomp was choosen. I know for simpler circuits like inverting amplifier and ideal integrator how Rcomp was calculated but following same procedure (that's using ...
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### What is topology of feedback for circuit?

I am confused between Voltage Shunt and Current Shunt Also mention why R2 shouldn't be considered as feedback as it is emitter degeneration resistance Consider the above circuit why can't I consider ...
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### How to proove if any circuit have negative feedback?

Queries regarding this circuit I am able to say that this circuit has negative feedback but my procedure is disorganized I want a step wise procedure to identify the polarity of feedback In this ...
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### How to find input impedance of this OPAMP circuit?

Assume OPAMP to be ideal with infinite gain (a) and infinite input impedance I am clearly able to see that the input impedance of this circuit is R1 (correct me if I am wrong) but I am unable too ...
129 views

### TL494/TL594 measure current with grounded load

Multiple examples of current limiting with TL494/TL594 suggest to use current sensing resistor between load(-) and GND. But I want load to be grounded. Can current sense resistor be placed above load(+...
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### What will be vo/i for given circuit?

Solve using both approaches first using small signal analysis and then using feedback analysis.
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### What will be small signal trans resistance gain of shown circuit?

Take beta = 99. I analysed this circuit using first considering this circuit as feedback circuit with shunt-shunt type of feedback and then did the same analysis considering that the circuit is a ...
72 views

### How to find voltage gain of below analog circuit without using Nodal analysis?

This is a theoretical circuit just made to see that if I can find voltage gain of circuit and it took me much calculations then anticipated to get voltage gain.I just want to find if there is better ...
66 views

### Powering up second LM386N results in screaming squeal

So I'm definitely a newcomer in the audio electronics realm but I've been really digging into circuits and experimenting with sounds. I've been focusing alot of time working through examples that use ...
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### How to Implement this BEMF Observer

I'm using the lecture by Dave Wilson at TI to implement a BEMF observer. I have the motor winding currents for phase A, B and C. I also have the Bus Voltage I also am in the stationary reference ...
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### How do I find this value for the feedback fraction?

How exactly do I find this value for the feedback fraction Beta? Thank you. omega_0 here is the natural frequency calculated as omega_0 = 1/RC and s is the complex frequency.
106 views

### 555 square wave generation with frequency feedback

Knowing that 555's behaviour varies according to temperature, I wondered: In an astable configuration, is there some way to measure output frequency, compare it with some desired value, and use this ...
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### Difficulties simulating transimpedance amplifier

I am developing a transimpedance amplifier as an assignment for a faculty course and I am running into problems when trying to simulate my circuit in ADS Keysight, even though I am quite sure how my ...
168 views

### Output impedance of a series shunt feedback amplifier

I am trying to find the output impedance of a series shunt feedback amplifier by converting it to a two port network. I know the input impedance: Ri=ri*(1+A.β) But I dont know how I should find ...
56 views

### Feedback Circuit schematic to Control Theory block diagram?

I'm studying analog electronics circuit with feedback. I see that, during analysis, a useful abstraction over the schematic is the block diagram in control theory style, but I stuggle in deriving it ...
122 views

### Difference between two integrator circuits

What is the difference between the two integrator circuits? They are used in an amplifier with feedback. There's heaps of information online about the one on the right but not so much about the one on ...
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### Finding the negative feedback loop in the amplifier circuit

Today I was learning about the negative feedback in the amplifier circuits and some quick ways of discovering whether a negative or a positive feedback exist in the circuit by finding a feedback loop ...