# Questions tagged [frequency-response]

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58 views

### Frequency-dependent behavior of R and L in LTspice

I have this question that I have been dealing with for quite some time now. Say I have an electrical machine that I model using lumped parameter (RLC circuit). As we all know, R and L are frequency-...
60 views

### Magnitude calculation of filter

I am working on a problem for a given transfer function given below and am having trouble calculating the magnitude and phase of it. The problem is specifically that I do not know what method to use ...
63 views

### Generator voltage dipping at specific loads with observed increase in frequency

Background I have an interesting problem at hand on a diesel generator onboard a marine platform. The generator is rated at 380V, 50Hz, 3Ph and 1500kW output. Problem While conducting installation ...
88 views

### Frequency dependent impedance as an electrical circuit

I am having problems trying to custom fit a frequency dependent behavior. I want to be able to convert a frequency dependent impedance Z(f) into an electrical circuit of the sort 1. The input of the ...
36 views

### KHN biquad: why does LTSPICE plot a wrong phase plot for bandpass filter?

I'm studying the KHN biquadratic section and its outputs to obtain a lowpass filter, a highpass filter and a bandpass filter. I simulated the filter using Mathematica and obtained the following plots, ...
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### Cartridge heater frequency response [closed]

Does anyone know the typical frequency response of a cartridge heater? Normally they work from 120/230 Vac 50/60 Hz, but I would like to know: If it is possible to use a DC source (120/230 Vdc). What ...
43 views

### Gain error calculation for op-amp circuit in inverting configuration

For an inverting op-amp, calculate minimum gain that is required for the op-amp to achieve a gain error of 1%, if the required closed-loop DC gain is -9. If the input resistance R1 is 1Kohm,find the ...
114 views

### Level transformation 0/+5 V TTL logic to +/-9V how to maximize gain and frequency range (DC to 4 MHz)

I see a lot of repeat answers and instructions how to convert dual supply levels to logic levels, but I have the inverse situation, converting 0/+5 V TTL logic to +/-9 V, and I don't see a lot of info ...
55 views

### Analog CMOS Design

I have been studying CMOS design from Baker's book. In the amplifiers chapter he places a "big" resistor between the input gate and output drain of CS derived amplifier stages. What is its ...
50 views

### Emulate impedance response using RLC components

I need to emulate measured impedance response of some blackbox using only RLC components. Measurements: ...
39 views

### Frequency response measurement problem with mobile phone: same (wrong?) readings for different speakers

I have built some bespoke speakers and tried to measure their frequency response. My rig is: Source: Android phone Samsung A3 as a source, playing frequency sweep using Android's Frequency Generator ...
441 views

### Transfer function of electrical network

I need help with this problem. The transfer function that I found is ((RCS+1)/(2RCS+1)) , but then I cannot go further because the form of T.S is untypical. The typical form of this question is RC ...
87 views

### Why does this ramp generator drop level outwith 60Hz / 10kHz range?

I found the following circuit in an old Elektor article: It is a [edit: ramp generator] that repeatedly (a) charges C3 through R4 to build a ramp, and (b) briefly shorts C3 across T1 to reset the ...
70 views

### What is the different bewteen the minimum attenation in butterworth and Chebyshev filter?

I have desgined n of a low-pass butterworth whose specification are fc=1khz , fs=2khz, Amax = 1 db and Amin=40 db. I found that I need to make sure the n gives me larger Amin which = 40db. So I ...
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### How to explain the peak frequency and resistance relationship in this op amp circuit?

I was studying thid tutorial by Simon Bramble. I changed the original circuit a little bit and this is the subject of our discussion: As you see, R1, R2 and R3 are all 1kOhm. When I run an AC ...
25 views

### Realisation conditions for impedances

Given a frequency function, which conditions should it fulfill to be realisable and implemented as a one-port impedance? I know that for it to be realisable with passive RLC components, the frequency ...
29 views

### Differentiator Op-amp with a triangular wave

I’m trying to create a differentiator op-amp. The input signal is a triangular wave of frequency 100Hz and amplitude 1V. The circuit I have designed features a series resistor (Rin) and capacitor. ...
89 views

In a superheterodyne receiver, let us assume, I have a signal in the RF range of 88MHz to 108MHz. From what I have read, my understanding is that by tuning the local oscillator frequency, we can make ...
38 views

### How to visually determine the damping ratio when we know the peak amplitude

I am currently trying to understand this example from the book, where it visually calculates the dampening ratio given the peak amplitude as well as the natural frequency. Here is the graph from which ...
58 views

### Why isn't my the LTspice cutoff frequency for my multiple feedback low pass filter not matching?

I am designing a 6th order multiple feedback lowpass filter with cutoff frequency at 1000 Hz. I wrote a matlab script that calculated the capacitor and restore values. I combined all transfer ...
28 views

### Determining Z1 for voltage divider of RF Matching Circuit

I have a problem where I was given an RF circuit with a series RL load. I am tasked in finding a matching L circuit and determining the values of the components. I used a smith chart to determine that ...
189 views

### Why are the theoretical and measured frequency responses off a low pass filter different?

The calculated/theoretical value for the cutoff frequency was different to the measured. What is the reasoning behind this other than measurement errors? It should be noted that this was a simple ...
1k views

### What does a bode plot represent and what is a pole and zero of bode plot?

I studied bode plot and the author of book is somehow relating zeros of transfer function to bode plot. What is the relation between zeros or poles of bode plot and transfer function? We usually take ...
332 views

### More equations than unkowns in amplifier circuit

I am trying to find the Magnitude Response of the gain of this amplifier circuit. The gain formula is: $$H(\omega) = \frac{\tilde{V_{out}}}{\tilde{V_{in}}}$$ My amplifier circuit is as follows:...
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### Automated Approaches for Measuring Audio Amplifier Frequency Response

I'm looking for a DIY or professional method for easily measuring frequency response of an audio system from 10Hz to 10kHz. It is for a guitar amplifier, and I would like a better way to characterize ...
821 views

### Why does a square wave in frequency domain have less amplitude?

For a square wave in time domain to frequency domain, the amplitude decreases, as shown in the spectrum image below. I dont understand why the amplitude decreases. In the time domain, it looks ...
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### How to get a flat band frequency response with an inductive input

I have a primary inductor L1 connected to a voltage source with frequencies varying from 0.5MHz to 15MHz. This primary inductor induces a voltage across a secondary inductor via coupling and I want to ...
78 views

### 3-dB frequency of cascaded opamps

We have two identical opamps with a first order low-pass response. They both have the same 3-dB frequency $f_1$. I need to show that their combined 3-dB frequency (when they are put in cascade) is: ...
162 views

### Frequency response of this circuit

Im not sure how to find the frequency response ($H(jw)=V_o/Vin$) of this circuit Can anybody help please?
54 views

### Frequency Response of Current Transformer?

I want to get frequency response of an CT in practical applications. Current transformer is nonlinear systems and i want different ways to get it in practice. Which software is better for analyzing ...
105 views

### RFI filter modeling in LTspice w/ triac

I have a few questions about modeling an RFI filter in LTspice with a triac-based dimmer circuit. I'm referencing the circuit described in Figure 11 in Triac Principles and Circuits -- Part 2 (Nuts &...
138 views

### Replacing s with jw in transfer function. When the input function is oscillatory and has exponential decay

I understand a version of this question has been asked numerous times before but I could not find an answer to this specific one. This is how I understood replacing s with jw. From the impulse ...
51 views

### Improve the frequency of Current Source Howland effect Op-Amp

I need help on a Howland Effect circuit with a current source purpose with an output of 600mA and a constant gain throughout a range of frequencies starting in 0Hz to 1Mhz. I am currently using an ...
599 views

### High vs Low audio transistor hFE (DC Current Gain). Which is better?

I'd like to preface by saying Rest in Peace my SoundBlasterX's back-panel transistors. What I tried to do, shown in the images below was ground the copper heatsinks I had glued onto the metal side of ...
271 views

### Frequency Characteristics of Low pass filter

Can anyone explain to me how I would find the frequency charactertics of a low pass filter? How can I choose frequencies and find corresponding gains? Is the frequency from the x-axis constant or ...
95 views

### Capacitor as filter, physics behind choice [duplicate]

I am tapping into the output voltages (signal wire) of various sensors on a vehicle, and I would like to use decoupling capacitors to filter out noise. As others have stated, a rule of thumb is to ...
915 views

### Dominant Pole Approximation

I am studying Microelectronics by Behzad Razavi, 2nd Ed., where in the frequency response chapter it uses the "Dominant Pole Approximation" to find one of the poles easily from a quadratic denominator ...
85 views

### 2 Crossovers in parallel: how are frequencies distributed?

So, the other day I connected on parallel a dual-voice subwoofer-system (a Pyle XSUB1-150-4-12d crossover — like this one ... link might be unavailable after Aug 28, 2019 ... — and 2 individual ...
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### Frequency response of MEMS sensor in datasheet

I am looking for a MEMS acceleration sensor and the frequency range of 0 to 20 Hz is required. But after checking a lot of datasheets I am confused. Because in most datasheets I am unable to find any ...
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### Is the frequency response of a circuit only valid for steady state (phasors)?

This is my first post. I just finished a course about advanced circuit analysis techniques (the content was taken from textbooks by Sadiku, Hayt and Irwin.) As you know, phasors are used to solve ...
183 views

### Difference between simulated and constructed filter

I recently designed a passive RL ladder filter to obtain certain specifications for anti-aliasing purposes (circuit shown below and simulated in LTSpice). The response I got in LTSpice was very ...
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### How can I export the frequency response from LTSPICE without phase wrapping?

After I plotted the frequency response of a circuit using LTSpice as shown: I exported the plots data as a .txt file in order to plot them after that using MATLAB, however, after I plotted the data ...
185 views

### High Q peak in frequency response means what in time domain?

Reading Linear Circuit Transfer Functions and one of the graphs got me curious. I've recreated the circuit (series RLC) and plotted the frequency response for a Q of 7. We have a peak of ~16.3 dB ...