Questions tagged [frequency-response]

For questions about the frequency response of electrical circuits. Also consider using the related "bode-plot" and/or "nyquist-plot" tag if your question involves a Bode and/or Nyquist plot, and/or the "stability" tag if your question is about the stability of an electrical circuit.

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Does a resonant peak produce a distorted wave form?

Context I am re-enforcing my understanding of the frequency response. From 1, I understand that, In an audio system, [the frequency response] may be used to minimize audible distortion by designing ...
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Gain crossover frequency in bode plot for control system

I know that gain crossover frequency (freq at which gain is 0dB) is where the phase margin is calculated. I also know that the gain crossover freq must be lower than phase crossover freq for stable ...
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1 answer
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Unexpected resonance behaviour in LC tank resonator coupled to Cockroft Walton

I am creating a powerbase for an instrument that requires a potential difference that increases in discrete steps, and am attempting to power it with a Cockroft Walton (CW) voltage multiplier circuit. ...
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4 answers
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Why doesn't compensation capacitance add additional phase for OpAmp?

The following image depicts the transfer function of an compensated against an uncompensated OpAmp. If the internal Miller-compensation capacitor results in an additional pole at low frequency I ...
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2 answers
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How can I understand amplifier types?

I am studying for my final exam. I am struggling a bit with the frequency response formulas. For instance like this circuit, the formulas generally are the same. I don't know what type amplifier it ...
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3 votes
3 answers
534 views

Intuitive understanding of relation between phase margin and peak overshoot and/or damping factor [closed]

Second, percent overshoot is reduced by increasing the phase margin, and the speed of the response is increased by increasing the bandwidth. "Control Systems Engineering, Norman S. Nise" ...
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MOSFET - Frequency response

I tried to do an exercise from my textbook where I have to discover the gain for mid frequencies of the MOSFET below, but I can't solve it. I got stuck at one point. I drew the small signal ...
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How to determine difference between LHP poles and zeroes by observing Nyquist plot?

I am solving practice problems on Nyquist Plot and I got stuck at a problem having a solution which I do not get at all. Here it is: Which of the following is the transfer function of a system having ...
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1 vote
2 answers
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Finding the frequency of a RC network pole given the relative gain at a frequency

In the Texas Instruments application note "Single-Supply, Electret Microphone Pre-Amplifier Reference Design", the following circuit is discussed in section 2.1: simulate this circuit &...
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Pole - zero cancellation for frequency compensation

i am now designing an opamp used for feedback network and taking frequency compensation to help phase margin by killing the big "mirror pole" at node E (the left circuit) using R-C topology (...
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Frequency Response of Antennas

Electromagnetics and antennas are not my main area of expertise. However, I have a specific question about antennas that I want to get right in order to make sure my signal processing is right. What ...
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8 answers
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Why is a capacitor considered a short circuit at start up?

The frequency response of a capacitor says a capacitor has a high impedance at low frequencies and it has a low impedance at high frequencies (up to the capacitor's resonant frequency.) If we use a ...
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Measuring capacitance with an oscilloscope and a function generator

I was looking for a method to measure capacitance at high frequencies and found this document from Tektronix. It shows how you can measure capacitance with an oscilloscope and a function generator. I ...
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4th order low pass Butterworth filter with very low Q factor [closed]

I have designed a 4th order low-pass Butterworth filter with a 0.707 Q factor. However, what I am getting is almost no flatness in the pass band region and my frequency response looks like a half of a ...
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2 answers
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AC voltage and frequency as complex number?

For some software I am writing, I coded classes of electrical systems that receive a voltage and return the current response. For the DC case that's easy: I pass a real number as argument, the voltage,...
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what is the surplus-control of generation?

Reading the ''P1 – Policy 1: Load-Frequency Control and Performance'' document, published by UCTE in 2009 (it is available on internet for all) I noted that there are many contributions to Load-...
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1 answer
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Parallel-series RC circuit

I wanted to calculate frequencies of filter The module of impedance which I got is equal What is the frequency cutoff of this circuit? I've made a simulation but I wanted to get frequency cutoff.
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Correct application of Miller theorem on a feedback two-stage transistor amplifier

I'm trying to estimate the lower cut-off frequency of this two-stage amplifier with feedback, assuming a dominant pole exists at low frequency. To do that, I want to apply the Miller theorem on the ...
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2 votes
1 answer
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Miller effect and Open time circuit method

Let's say I have a common source amplifier with parasitic capacitances Cgs and Cgd (it can be any amplifier but I gave this concrete example to simplify my question). In order to approximate the 3db ...
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4 answers
634 views

LC Low pass filter in LTSpice

I would like to model a low pass filter in LTSpice, but my frequency response looks like a bandpass, similar to an RLC filter. Is LTSpice incapable of simulating LC filters with an RC one?
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1 vote
2 answers
130 views

Frequency domain design of a PI controller for a first order system with transport delay

Let's say I have following first order system with transport delay $$G(s) = \frac{4563}{s + 64.77}\cdot e^{-0.000455\cdot s}$$ My goal is to design in the frequency domain a PI controller in the form $...
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Identify zeroes of circuit by inspection

In a circuit, we can approximate the poles of the transfer function by calculating the AC Resistance and Capacitance at every node. For every node we get a pole so a change of slope in the Bode plot ...
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3 answers
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Frequency response of low pass filter

I have an ideal low pass filter having cutoff frequency 1kHz. If I provide an input having single frequency component at 1kHz, will there be any output or zero?
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0 answers
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Modelling the PCB parasitic capacitance in LTSpice

I need to simulate the accurate behaviour of my attenuator made of an RC potential divider. Time constants of the top and bottom of my attenuator are matched. I noticed that when I inject a square ...
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1 answer
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Does every transfer function in a circuit have its own resonant frequency?

When I studied the resonant frequency of an RLC circuit in series and parallel, there was the definition that I read in books that the imaginary part of the total impedance of the circuit has to be ...
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Stability of the op-amp?

I am confused if the below amplifier will be stable or not when it acts as unity gain amplifier ( with a feedback factor of 1) ? My analysis: PM = zero from the bode plot , so the system is stable ! ...
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2 answers
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Why is closed loop frequency response hard to determine?

I'm learning about frequency domain control design and one of its advantages is said to be that: one can deduce the closed loop behaviour of a system by (experimental) data on frequency response on ...
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4 answers
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How to verify the voltage and frequency response in a simulated equalizer?

I am working on a simple equalizer, intended to filter bass, midband and treble frequencies. I'm wiring the bode plotter of Multisim in a wrong way,perhaps. The circuit is: The idea is to measure the ...
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Linear and log sweep in AVR

My application requires a frequency sweep in a coil and measuring the resultant resonant frequency from the coil after it has settled. I can do the second part i.e. wait and count the rising edges of ...
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-1 votes
3 answers
181 views

Non-linear amplifier

An amplifier has a non-linear response given by Vo= aVin +bVin^2 at all frequencies. When a sine wave of amplitude 1V is input to the amplifier the output of the amplifier contains a harmonic at -80 ...
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1 vote
4 answers
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Calculating the theoretical frequency response and static gain of a filter

I'm trying to calculate the theoretical frequency response and static gain of this low-pass filter. As far as my knowledge goes, calculating them using experimental means would be simple, but how ...
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0 votes
2 answers
142 views

Cut-off frequency of simple transistor circuit with capacitance between input and output

I have the following problem: - simulate this circuit – Schematic created using CircuitLab For the amplifier shown in circuit 1, the open circuit voltage gain at low frequencies was calculated ...
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1 answer
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AC analysis with positive/negative current paths having different Impedances

I am simulating a spring-mass-damper circuit. I want to see how various damping scenarios perform in the frequency domain. I have linear, progressive, and digressive scenarios working... Now I want to ...
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1 answer
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What is the desired total low frequency response for a common emitter amplifier? [closed]

For a common emitter the total low frequency response is different, depending on the values of input, output and bypass capacitors. Three separate cutoff frequencies: One cutoff frequency when all ...
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1 vote
1 answer
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Magnitude of a Transfer Function

So I have an unknown circuit with a plot like this: From this I have to determine a likely transfer function model. It looks to me like there is a pole at 50 rad/sec and a zero at 1500 rad/sec, with ...
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0 votes
1 answer
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Does differing mains frequency affect DC motors?

I moved a large, high-quality kitchen appliance (a stand mixer) intended for use in North America to the UK. To operate it without damage to the motor, I will need to (at least) convert the voltage ...
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0 votes
1 answer
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How to measure the frequency response of a waveform generator?

I was looking at the data sheet of an arbitrary waveform generator and found a plot of the frequency response of the instrument, then wondered how it was measured. I know how to measure the frequency ...
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5 votes
2 answers
431 views

What is the phase margin when there are multiple gain crossover frequencies

I am using LTPowerCAD to help design a buck converter circuit using the LT8645S. I would like to add a second stage LC filter at the output to achieve lower output ripple, but when I add the second ...
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0 votes
1 answer
146 views

Transfer function of an op amp with an Y or delta

What's the transfer function of the op-amp with a Delta from figure one? Such circuit can be easily converted into an Y, figure 2. Tina is calculating the transfer function from the Y circuit as H(s) =...
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0 answers
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Linearly or logarithmically spaced frequency vector?

I am trying to compute the impedance of a circuit over a wide frequency range using the finite element method (fem). To do this, I apply an fft to the input voltage. Its spectrum starts at f_start = ...
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1 vote
2 answers
406 views

How to analyze low pass filter in voltage divider?

In some guitar pedals I've seen following circuit to provide a stable voltage between ground and the supply voltage (labelled as INPUT below). I think this forms a ...
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1 answer
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Finding the position of a zero without doing explicit calculations

I have the following circuit: It is a fully-differential amplifier. Since the circuit is symmetrical with respect to the vertical axis, only the right portion (for example) can be studied to find ...
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2 votes
2 answers
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Ideal closed-loop gain derivation for negative feedback

Considering a negative feedback system, the closed-loop transfer function Af is given by: where A is the open-loop transfer function and AB is the loop gain. Every text I read says that if the ...
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2 votes
1 answer
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From where can I get the impedance graph/ frequency response information of a capacitor?

I want to know the self resonant frequency (SRF) of a tantalum or aluminum capacitor. Is this usually supposed to be there in the datasheet? I am wondering why it is not mentioned in datasheet since ...
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2 answers
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I am struggling to understand how to show the cut-off frequency

I understand that the cut-off frequency f = 1/(2πRC) or 70.7% from the maximum. The issue I have is I don't understand how these end up being 2 different points on my graph. Above is the cut-off ...
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0 votes
1 answer
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Can someone explain this trend of Control Voltage Vs Output Freq? Circuit configured:- 555 IC as a VCO

So, in my Master's, while going through a lab for analog electronics, we were given this seemingly pointless task of plotting Control Voltage vs Output Freq when a 555 IC is configured as a VCO. The ...
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2 votes
2 answers
493 views

Building a band-pass filter using an op-amp

I am quite new to op-amps but have looked at them in college and have done my own research on them. I am trying to use an op-amp to build a simple band-pass filter which has an in-band voltage gain of ...
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Can an ADXL327 accelerometer be used with theoretically unlimited bandwidth?

I saw several studies that use the 3-axis ADXL327 accelerometer, 0.1-3000 Hz band-pass filtered and sampled at 20KHz based on previous studies that showed that the signals of interest have frequencies ...
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6 votes
4 answers
240 views

Why do log sine sweeps traditionally start from low frequency?

I'm doing a log sine sweep to get the frequency response of a device. The software works fine, but the first low frequency half period introduces a bit of DC offset in the signal coupling caps, so ...
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5 votes
2 answers
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Why are low values of resistor in non-inverting configuration of opamp causing gain peaking?

I am trying to simulate frequency response of TLV07 in non-inverting configuration for gain 10 as shown below: The frequency response shows peaking as shown below: It is worse for smaller values of ...
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