# Questions tagged [frequency-response]

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### Help for analog signal chain for 16bits ADC

I work on analog amplifier and filter chain for an internal STM32H753VI 16bits ADC. The signal chain is based on ultra-low noise opamp LT6237 and differential driver LT1994. The sample-rate of ADC ...
81 views

### RC filter impulse response is exponential decaying but inverse Fourier is Sinc function

As we all know that the inverse Fourier transform of a frequency domain unit pulse/rectangular function (which looks like low pass filter) is Sinc function. So, I was under the impression that any low ...
40 views

### how to find Vout/Vin in this circuit? BJT frequency response

I have been struggling for 1 hour trying to relate Vout to Vin. However, I truly cannot. I tried KVL, node analysis etc everything that I could. Can you help me pls? The topic is frequency response of ...
45 views

### Find i/o pole of the cascade (BJT)

I have to obtain the pole of this circuit and the conversion function, but I can not do it . How many poles does this circuit have? And what are their relationships according to the arrangement of ...
280 views

### Approximating the dirac delta function on LTspice to find the impulse response of a high pass filter

I have an assignment which requires me to find the impulse response of a high pass filter on LTspice. In order to do this the question suggest feeding a Dirac delta function as an input to a simple ...
58 views

### Are harmonics always the peaks in the frequency response plot?

I would like to implement a certain type of audio alarm with 1 fundamental frequency and 4 harmonics. The example frequency response of a qualified alarm on the spectrum analyzer is shown in the ...
74 views

### Electromagnetic radiation from spark gap

I am an electrical college student. I learned from some papers, sites online, including this forum that lightning discharge or any electrical arc emits wideband radio frequency because the odd integer ...
57 views

### 1-10Hz frequency count translated to PWM for stepper motor RPM

I would like to control the speed of a stepper motor based on an input signal that consists of short 12V pulses at a varying frequency of 1-10Hz. I know this is an easy task with a microcontroller but ...
39 views

### Bandpass filter obtained by complementary transformation of lowpass Sallen & Key: what went wrong?

I am considering the following lowpass Sallen & Key filter: My components are the following $R_1=10 k\Omega$ $R_2=10 k\Omega$ $C_1=150 nF$ $C_2=1.65 nF$ Now I have performed a ...
65 views

### 2nd order Sallen-Key low pass filter frequency response

I am trying to implement the following circuit in LTspice for studying the frequency response of the 2nd order Sallen-Key low pass filter for a project. Why am I getting a negative peak in the ...
127 views

### Upper 3-dB frequency of differential amplifier with current mirror load vs with resistive load

In the BJT case, why is it that the upper 3-dB frequency of a differential amplifier with a current-mirror load (1st picture) is lower than that of a differential amplifier with a purely resistive ...
41 views

### Suitability of standard-gain pyramidal horn for UWB signal

Objective I'm interested in evaluating the suitability of a standard-gain pyramidal horn for an ultrawideband (UWB) signal. However, I've had difficulty finding reliable information about the phase ...
70 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-...
68 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 ...
71 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 ...
94 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 ...
78 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, ...
42 views

### 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 ...
95 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 ...
144 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 ...
57 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 ...
51 views

### Emulate impedance response using RLC components

I need to emulate measured impedance response of some blackbox using only RLC components. Measurements: ...
40 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 ...
573 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 ...
88 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 ...
71 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 ...
91 views

### 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 ...
45 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. ...
98 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 ...
56 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 ...
102 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 ...
29 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 ...
396 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 ...
2k views

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

I studied Bode plots and the author of my book is somehow relating zeros of transfer functions to Bode plots. What is the relation between zeros or poles of a Bode plot and transfer function? We ...
336 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:...
54 views

### 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 ...
988 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 ...
48 views

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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 ...
92 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: ...
167 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?
61 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 ...
138 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 &...
231 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 ...