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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What's the deal with this comparator's hysteresis?
I have here a circuit designed by someone else to create a 50% duty cycle square wave that leads a current transformer in phase. The CT maxes out at about 1 amp, and the output of the phase-leading ...
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Can this oscillator possibly work?
I am trying to build a crude RF oscillator. My first attempt, though it simulated fine, disappointingly did not oscillate when soldered together. So, to debug this, I reduced the simulation example ...
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Zener instead of resistor divider on dc-dc converter feedback pin
This dc-dc converter steps up voltage from 3.1V to 7.5V. I'm curious about the unusual D2 zener + R3 resistor to set the output voltage, instead of the traditional resistor based voltage divider. I ...
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I need help to identify the negative feedback loop in a hysteresis comparator
Can anyone help me identify where the negative feedback path is?
I want to determine the feedback factors for both negative and positive feedback, but it's not clear to me where the negative feedback ...
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How to simulate a uniform distribution around zero in LTSpice?
I am using LTSpice for a Monte-Carlo simulation, I typically use the function {mc(x,y)} for componant variability
I also want to introduce spread in the feedback ...
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Op-Amp oscillations when controlling P-MOSFET Vgs
My background is digital design, I guess the answer is obvious for all here, but not for me.
I am studying example of analog physical layer for USB 2 protocol which I found in this paper. Also ...
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Why don't we use an integrator as the loop filter of a PLL?
In a book on phaselock that I was reading, it mentioned that ideally, one would use an ideal integrator as the loop filter of a PLL. Since we can implement integrators with op-amps, why don't we use ...
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Where is the phase shift on this oscillator?
I didn't think the oscillator below could work, but I built it, and it does:
I used 10 uH for the inductor, 2.7 nF for the capacitor, and got oscillations around 8 MHz.
The feedback loop is a series ...
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What requirements of a feedback network are needed to produce oscillation?
I'm trying to understand how to analyze simple oscillators, and would like to know if my conclusions about the required feedback network are correct:
The simplest way to build an oscillator is with:
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LTSpice simulation produced different results of phase margin when using step-signal % overshoot technique vs loop analysis technique
I am working on a class AB amplifier circuit to that can output both AC and DC current, controlled by an op-amp with feedback from the final output. The output will be driving an 50uH inductor.
The ...
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How to solve non-ideal opamp circuit using feedback properties?
Is there a neat way to solve this using feedback properties? Or if you know a better method to solve this, please suggest one.
It would be straightforward if we assume an ideal opamp in this case, ...
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MOSFET feedback mechanism
I made an simple feedback circuit. R2 and R3 is voltage divider there so I'm setting them sufficiently big values. But in this setup, it works with 2N7002 and not IRFZ44N (gain is way less then I set ...
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Am I correct in solving this Loading in Voltage-Voltage Feedback
The following circuit is from Chapter 13 of Analog Design Essentials written by Willy Sansen.
Calculate \$R_{out}\$ for this circuit.
Break close loop with loading effect.
$$
(V_{in} - V_X) g_{m1} +...
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Why does this simple op amp create an AM modulated envelope over its carrier?
The circuit below is an ideal op amp (requires no power, can produce any output voltage) in LTSpice:
LTSpice shows it amplifying the 159.155 kHZ input, as expected. But it also shows a 2500 kHz AM ...
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How can you tell whether it's either voltage-current or voltage- voltage feedback?
The following circuits have different feedback.
Resistor \$R_F\$ senses the output voltage and returns a proportional current to node \$V_X\$. Thus, the feedback can be considered as the voltage-...
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