# Questions tagged [bode-plot]

Anything related to Bode plots, i.e. a special graphical representation of the frequency response of a linear time-invariant system.

147 questions
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### Why is the Bode plot of 1/s a straight line?

The magnitude of the impedance of a capacitor is $(\omega C)^{-1}$. Plotting the impedance vs frequency should be a curve with slope $-1/(\omega ^2C)$. Why is it plotted as a straight line with a ...
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### Why Deliyannis bandpass filter with high Q does not have the expected transfer function bode plot

What i need is to design a delyiannis band-pass filter with Q enhancement technique. The theoretical analysis of this technique is referred here in pages 107-112. For those who don't know how to ...
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### Choosing a position sensor (encoder) and obtaining velocity from it

How do I know how many counts per revolution I need for an encoder for my application? I need to be able to accurately capture a 1000 Hz signal on an input side running from 1-133 rev/sec (60-8000 ...
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### Nodal analysis -> transfer function -> step response

I've been trying to get the transfer function for the circuit in the image below, but I seem to be doing something wrong, since the simulation on Circuitlab gives me a different Bode plot and I can't ...
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### How to estimate the transfer function given only Bode plot data points?

I'm trying to obtain transfer function given Bode plot data points. As an example I used the following RC filter and made AC sweep as follows: I set the type of sweep to decade and for each decade ...
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### Confusion with Bode plot in LTspice when using a voltage regulator

To experiment(out of curiosity) the effect of a low pass filter for an SMPS switching noise I wanted to try a filter where an LC cascaded by a linear regulator as shown in below diagram, I obtained ...
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### Obtain a Transfer Function from Bode Plot shown

I want to obtain a Transfer Function from the Bode Plots I already got the corner frequencies (approximates) and all the terms for my T.F. Then when I try to check my results in MATLAB my plot drops ...
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### Is my measurement setup correct for the common mode frequency response?

I’m using a USB scope which can be used as also a network analyzer. For a network like a passive filter, to obtain Bode plots one input channel is set for reference the other as output. And the input ...
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### What does actually the “unravel branch wrap” option do to the phase plot in LTspice?

Below two Bode plots are identical just that in the second one the option "unravel branch wrap" is unticked for the phase plot: What does this option do to the phase plot?
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### Whats the difference between bode plot linear and cartesian?

As in title, Whats the difference between bode plot linear and cartesian in LTspice? In both cases i get V(f) but the values differ. Which plot will give me values of voltage at given frequency that ...
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### Understanding log-log axes

In below picture there are two graphs representing the function $H(s) = s-z_1$ (assume $z_1=2$ is a constant). The left graph has $\omega$ on x axis and $\|H(j\omega)\|$ on y axis. The right ...
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### How to determine the phase margin and transfer function of this bode plot?

I have some struggles to find the transfer function of this plot. We got the hint, that the "breaks" of slope can be assumed to be on vertical and horizontal lines. Also we should pay attention on the ...
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### determine the cutoff frequency of a nMOS in common gate with gate resistance

I have to determine the upper cutoff frequency of this circuit. I absolutely mustn't use the laplace domain because it's too time consuming so not compatible with the time I have at the exam. A rapid ...
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### Quality Factor and Cut-off Frequency Defintion

Suppose we have $$H(s) = \dfrac{ k \frac{\omega_o}{Q}s}{s^2 + \frac{\omega_o}{Q}s + \omega_n^2}$$ What is the definition of the quality factor? My understanding is that it is the gain at the cut-...
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### How do I integrate a function and plot the result on Matlab?

I need to plot a function that has an integrate inside, but I don't know how to do this on Matlab. Function: $SOC(t)= SOC(0) - \dfrac{1}{Q}\int_{0}^{t}i_2(t)dt$ time is in hours, current is in ...
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### 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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### 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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### How to calculate, *for a square wave input*, the cut-off frequency point for a basic RC low pass filter with

I am applying low pass filter for a pcb circuit I am trying to design (picture below). I have managed to calculate the cutoff for a sine wave input since I can insert a frequency (i.e. f_c = 720 Hz ) ...
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### A weird question about the cutoff point of an RC low pass filter

I have read the linked explanation about the RC low pass filter circuit and understood most of it. I understand the relation between the time constant RC to 1/(2*pi*f_c). I understand it means there ...
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### Gain of proportional Controller with distubance $sin(10t)$

The diagram below represents the position of ocean oil platform system which use the proportional controller with gain $k$. The output $x(s)$ is the platform deflection regards the position ...
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### How to plot the open-loop gain of an inverting amp, difference amp, and low pass filter?

For example, if we are using the ADA4004-1 op amp in all these circuits, the open loop gain is 400000 as shown in the spec sheet (Table 2): ADA4004 Datasheet The open-loop breakpoint is at 30 Hz (...
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### 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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### 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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### dc to dc converter bypass capacitor consideration

I using a TI buck regulator (LM21212) to power a bunch of components on my board at a certain voltage. When calculating stability, do I need to take into account all the decoupling capacitors (e.g. 0....
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### What form for Transfer Functions to use for filters and Bode plots?

I've seen some different forms for the equation of a transfer function and wonder which one is most correct and why? Does it depend on type of filter etc.? Let's take an example and its transfer ...
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### RHP zero with a positive phase shift

All books and references I read say that RHP zero gives a negative phase shift. I can infer that by plot the phase of the function $w_{z}-s$ where $w_{z}>0$. With this function, when frequency ...
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### Why does my cutoff frequency not match the 3db down point?

My understanding is that the cutoff frequency of this circuit can be calculated simply by: 1/(2*pirc) I get a cutoff frequency of 15.9kHz But as is shown in the provided bode plot 15.9kHz is ...