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Questions tagged [frequency-response]

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2answers
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Can I change op-amp supply voltage without affecting circuit behaviour

I am working on an audio project which is based upon various sections of several different schematics from various old musical instruments. I want to make a test board that has multiple different ...
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1answer
49 views

Can a system have constant phase response other than +/- 90 deg (and multiples)?

I have seen frequency responses where amplitude response is constant( pure delay) and where phase response is constant(pure integrator). In an integrator the constant phase is -90 deg. In a pure ...
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1answer
25 views

LTSpice transient analysis and current amplification problem

Im simulating LC circuit in LTSpice: It's tuned at resonance at 1 MHz in the transient response simulation plotting the source and R1 current. Both of which are equal in amplitude 600mA but with a ...
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1answer
34 views

Resistor's behaviour at high frequencies

Looking at the impedance vs. frequency graph 1) At low-frequencies Z=R and hence it would be a straight line. 2) For mid-frequencies, Z decreases possibly due to capacitance, but I'm not sure ...
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1answer
49 views

2-stage BJT CC-EC amplifier [closed]

Using proteus I designed this amplifier: But I got this result: I don't know what is the problem in my design. I've been changing the values of the linking capacitors but didn't get any result.
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2answers
47 views

Passive Elements At high Frequency [parasitic effects]

What would the magnitude Response curve for a Resistor, Inductor and Capacitor look like [with parasitic effects not ideal components] ? From what I have gathered they would look something along the ...
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49 views

Resistors at High Frequency

[external R at 100] []1 1)Why is it that at high frequency the magnitude of impedance of a resistor (100) decreases? 2) At High frequencies a resistor would have a parasitic component of inductance ...
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26 views

Frequency response: Response Graph, Gain calculations and other

1) Let's say that the frequency of the capacitor here was so low tending to zero such that the impedance for it 1/jwc would tend to infinity. Hence now this would act like an open circuit and so ...
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4answers
98 views

High frequency response of capacitors

I have studied the fact that the capacitor does not like a varying voltage across its terminals, and it acts as a short circuit initially so that there is no voltage drop across it. If this is true, ...
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14 views

Derive an expression for the current of a RLE rectifier

I'm trying to calculate an expression for this RLE rectifier: simulate this circuit – Schematic created using CircuitLab With \$R=2 \Omega\$ \$L=20 mH\$ \$V_{DC}=100 V\$ \$V_{m}=120 V\$ \$...
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1answer
37 views

Audio Frequency Response Offset in dB

Say I have some audio device with the following absolute frequency response: I want to shift the curve up, so that the 1kHz point is the 0dB point, and everything else is relative to this point. Am I ...
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2answers
183 views

High Pass Filter Design from Transfer Function

I need to design a circuit that implements the following transfer function: \$G(s)= G\frac{s+z}{s+p}\$ where, G = gain, p = pole and z = zero.
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1answer
30 views

Relation between bandwidth, response time and disturbance rejection for a control system

I read the following line in a control system book: Higher bandwidth corresponds to better command following, disturbance rejection and sensitivity to parametric variations. On the other hand, ...
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0answers
36 views

System requirement in frequency domain

Hi Can any one help understanding and interpreting figure 6a and 6b (page 6) in the paper attached down bellow : I need to identify first the transfer function of each plot and then interpret system ...
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1answer
32 views

How is the sweep type affecting the Bode plots for the same AC analysis in LTspice?

When I do an AC analysis for the following circuit between 0.1Hz upto 20MHz, and by selecting "decade" in sweep types I obtain the following plots: But if I do exactly the same thing only this time I ...
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1answer
371 views

Frequency response of MCU decoupling capacitor

I'm designing a board that contains an MCU and an 8 MHz crystal. I was planning on keeping the MCU power/ground localized and isolated from the main power supply power/ground except at a single point. ...
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1answer
35 views

VFA vs. CFA Compensation Capacitor Comparation

Here, I am referring to voltage-feedback amplifier (VFA) and current-feedback amplifier (CFA). A basic schematic is given below for each. I.) VFA II.) CFA I am curious about the position of ...
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2answers
71 views

Gain of Inverting Active Bandpass Filter

For the filter below I calculate the transfer function $$H(j \omega) = -\frac{R_2C_1 j \omega}{(1+C_1R_1 j \omega)(1+C_2R_2 j \omega)} $$ and thus calculate the gain $$A= \sqrt{ H(j \omega_o) H(- ...
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1answer
68 views

How are op-amp gain vs frequency response curves generated?

I have been wondering this for a while. When we look at the electrical characteristics of a device such as an opamp there is a gain versus frequency plot. I have couple of questions regarding ...
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1answer
51 views

What is the relationship between an amplifier's step input and the frequency sweep response?

What is the relationship between step input response and the frequency response of a system such as an amplifier? I see similarities between the step input response of an amplifier and the frequency ...
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1answer
58 views

Simple OP-AMP Frequency Response

In my textbook, there are two interrelated equations. 1. wb = wt / (1 + R2/R1) 2. wb = wt / Ao where ...
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0answers
24 views

What is the maximum number of natural frequencies given circuit elements?

I'm learning forced and natural responses, as an exercise the textbook gave 4 scenarios (2R&C, R&2C, 3R&2L, and 2R&C&L) and asked what the largest number of natural frequencies for ...
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1answer
88 views

Loop Gain and Phase Margin Correlation

I have found a definition of phase margin of amplifier system from Texas Instruments application report. This definition looks like this: $$\phi = tan^{-1} (A \beta)$$ where \$ A\$ is amplifiers open-...
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0answers
56 views

Frequency response of linear DDS chirp

I am performing a linear frequency sweep from 80 MHz to 120 MHz in 26.84 ms with the AD9910 direct digital synthesiser. I experience that the output amplitude is not constant (see Figure 1). With my ...
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2answers
124 views

How to define a transfer function for a given system?

I just finished reading this paper, on how to "draw" Bode plot for a given transfer function. After done reading I realized that it would be pointless to learn this stuff, if I wouldn't know how to ...
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1answer
68 views

Potentiometer Range in Speaker Frequency Response Curves

In several speaker spec sheets from CUI a frequency response curve is given, such as in the CLS0231MA-1: Notice the two y-axes: one for the potentiometer (0 dB to 50 dB) and one for the DUT (0 dB to ...
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2answers
103 views

What is the effect of PCB trace length to a capacitors frequency response?

I want to know the effect of PCB trace length to a capacitor's frequency response, especially in terms of bypassing and decoupling applications. For instance in the above simplified PCB, we have a ...
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3answers
112 views

What is the time derivative at t=0 for a second order low-pass step response?

For a first order system like an RC filter you have something like $$y(t)=1-e^{-\frac{t}{\tau}}\\ y'(t)=\frac{1}{\tau}e^{-\frac{t}{\tau}}\\ y'(0)=\frac{1}{\tau}$$ But for a second order system there ...
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1answer
25 views

Impedance response of a linear system is independent of the perturbation amplitude?

I'm studyng electrochemical impedance spectroscopy. On my book there is the sentence: "Impedance response of a linear system is independent of the perturbation amplitude.". Why? If I have a non-...
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4answers
101 views

Frequency response of an ideal LC circuit

Does the frequency response of an ideal LC circuit exist? The frequency response of a system is defined as: $$\int_0^\infty{h(t)e^{-j\omega t}dt}$$ where \$h(t)\$ is the system's impulse response, but ...
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1answer
55 views

Determine capacitor value gives amplifier characteristic independent of frequency

I have an amplifier for the needle EMG electrodes signal like image below. The question is : Determine the C2 capacitor value gives electrode–amplifier characteristic independent of frequency. Can you ...
2
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1answer
385 views

Frequency response of a parallel RC filter (smoothing capacitor in rectifier circuit)

I understand qualitatively and electrically how a smoothing capacitor works in the case of a diode-based full-bridge rectifier but what I am not too certain of is how to describe it in terms of its ...
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1answer
42 views

What's oscillatory instability in the delay differential equations?

Does DDE’s stability depend on forcing term and ODE’s stability does not depend?If yes, then is frequency analysis of stability applicable only to DDE and not ODE? In control systems, we study ...
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2answers
80 views

RC Filter measured response differs from calculated transfer function

I've created a first-order RC filter with R = 68 Ohm, C = 5.0 uF, and I am studying the transfer function of this filter. I have calculated the transfer function to be 1/(1+jwRC), based on the ...
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2answers
96 views

Poles and Zeros of Two Pole Compensation

I am known with the basics of what poles and zeros of transfer function are and how to determine them, but I certainly don't know how to apply such poles and zeros to the gain curve, which describes ...
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4answers
356 views

Units for fourier transform of measured voltage

I have a measured voltage signal that I want to present in the frequency domain. My current process is to take the FFT of the signal, then use \$20 \text{log}_{10}|X|\$ where \$|X|\$ is the magnitude ...
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3answers
214 views

What is small signal. And what is small signal equivalent circuit

I am very new in electronics. And this topic is bothering me. I want to know what is small signal and how to draw a small signal equivalent of jfet with common source.
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1answer
69 views

How can infer instability from the frequency response of control system?

When can we judge a control system to be unstable from its frequency response?.For example, thermostat computes the error signal (desired room temperature - actual room temperature) and then actuates ...
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2answers
713 views

How to calculate amplifier gain (in dB) using frequency?

I know how to calculate decibel gain using the ratio of power, or Vin/Vout. However, is there a way to calculate the magnitude of the attenuation and phase angle when you’re given the cutoff ...
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1answer
68 views

Frequency domain representation

I'm studying the space-state representation and I'm not understanding a simple situation that I created. I created the following system, on the frequency domain: By writing the time domain ...
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0answers
247 views

Speed of response and crossover frequency relationship

In SISO(Single Input Single output) cases, My professor keeps mentioning the speed of response and crossover frequency interchangeably. I don't really understand what the speed of response means also ?...
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3answers
99 views

Does an analog filter with complex impulse response exist in application?

Do we have in practice any analog filter that has a complex impulse response? Or they must have a real impulse response? Particularly, I am looking for a low pass filter that passes only a band in ...
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2answers
134 views

Double Peak Phenomenon in Transimpedance Amplifier Simulation

I'm simulating a transimpedance amplifier circuit in order to replicate a phenomenon that my team is experiencing. The phenomenon can be seen below in the image circled in red: My photomultiplier ...
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1answer
52 views

Can't draw bode curve of this zero

I have a transfer function like this: \$H(s)=\frac{s^2+\frac{1}{LC}}{s^2+s\frac{R}{L}+\frac{1}{LC}}\$ I can separate the denominator into an expression of the type: \$(1+s/a)(1+s/b)\$ and then plot ...
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2answers
462 views

The Pole Frequency of OP AMP 741

I am working on MatLab simulation software to plot a Bode plot in the Matlab Environment. The open loop transfer function is $$a(s) = \frac{a_0}{(1+s/\omega_1)(1+s/\omega_2)}$$ Where \$\omega_1\$ and ...
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1answer
72 views

frequency response multistage

hello every one i need ask about frequency response i have an old question of our professor exam in few year, and i try to solve this question many time but i can't so please if any one have idea ...
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1answer
878 views

OrCAD PSPice less than 2 connections error while simulating

I just started using PSPice and I don't know much circuits theory but I need to simulate this circuit and find Vout/Vin: I did this using capture but after running simulation I get this error: ...
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3answers
196 views

Transfer function gain [closed]

\$H(s)\$ is the transfer function and we're looking for its magnitude gain. I went from the Laplace domain to the frequency domain by replacing \$s\$ with \$j\omega\$. However, the solution didn't ...
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1answer
204 views

Frequency response of state variable filters

Could someone explain the difference between the following responses of a state variable filter? It looks as though the band pass response is approximately 3dB lower in the second image. Assuming a ...
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2answers
2k views

How to design a 2nd Order High Pass Butterworth filter with a gain of 6 dB?

I have been trying to design a 2nd order filter with a gain of 6 dB (or 2 Av), using the following Sallen-Key Topology. I have calculated R1 and R2 to give me a desired cut-off of 1.6kHz and this ...