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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.

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Bode diagram calculating for random frequency

The max Gain of an opamp is 100dB (=100000). I have a cutting frequency at 10 Hz and then the slope of my bode diagram decrease by -20dB/dec . I have unity gain at 1MHz. For 100 Hz its increasing by ...
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Bode diagram for RL circuit

I am trying to create Bode diagram for the following circuit: First I create the transfer function, I arrive to a point that looks like this (C is not capacity, sorry for bad name choice): I don't ...
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Proof of Bode-Fano criterion

I was reading this thesis and it mentions Bode-Fano criterion almost in every chapter of this thesis. Could anyone advise about the derivation of bode-fano criterion? Note: The original proof is so ...
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How to sketch the Bode diagram of the output filter of a Buck converter?

I'm trying to figure out the Bode diagram of the output filter of a Buck converter: simulate this circuit – Schematic created using CircuitLab Vout is ...
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49 views

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 ...
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LTSpice: Produce Bode Plot for Compensated & Uncompensated Boost Converter

I am designing a product which uses the LTC3122 as a 5V-12V boost converter (datasheet here). This particular device provides the ability to add gain compensation, phase lead, or both. In my case I am ...
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47 views

Gain deficit and phase margin at crossover

I went through an exercise of the following specifications: A voltage mode buck converter working in CCM mode works with: \$V_{in}\$ min = 10V, \$V_{in}\$ max = 20V \$R_{load}\$ min = 2.5 ohm \$R_{...
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86 views

Does frequency at zero matter?

Consider the following simulate this circuit – Schematic created using CircuitLab $$ H(s) = \frac{sR_2C_1}{1+s(R_1+R_2)C_1}$$ $$ f_z = \frac{1}{2\pi R_2C_1} $$ $$ f_p = \frac{1}{2\pi (R_1+R_2)...
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40 views

How is H(jw) = jw correspond to a slope on bode plot?

I cant understand how H(jw) = jw always intersects at "1" , also how the slope of the line is 20dB, Kindly explain, im having a hard time understanding because in book such stuff is not discussed,only ...
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65 views

Plotting bode plot, how the starting gain is in negative?

For function; \$H(jw)=10jw/((1+jw/2)*(1+jw/10)\$ To find starting gain, i did, \$20log(10)\$ which equals 20, but in matlab, it shows ...
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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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51 views

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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28 views

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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131 views

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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145 views

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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93 views

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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160 views

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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45 views

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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344 views

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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67 views

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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222 views

Low Pass Filter Wrong Pole Location

I wanted to understand and derive an equation of simple low pass filter that shows the location of pole in frequency response graph (Bode plot). So, here is the derivation: $$V_{OUT}=\frac{V_{IN}*...
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273 views

Bode Phase Plot of RC High-Pass Filter

I have been trying to understand Bode Phase Plot of RC High pass filter. I know that from my engineering that voltage lags behind the current passing through the ...
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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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58 views

Dynamic Compensator in Control Loop

Sorry if this has been asked previously, but I couldn't find anything here or elsewhere on Google (but maybe I'm searching the wrong terms). I'm trying to design a Type 2 compensator for a PWM chip I'...
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1answer
65 views

Determining Phase Boost needed to Compensate SMPS

I'm attempting to find the Control-To-Output Bode Plot (open-loop) of a SMPS designed around the TPS54160 so that I can design the type II compensator. The first step in designing a compensator is ...
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45 views

Bode Plots - Absolute Value of Complex Function in Magnitude calculation

I'm struggling with one step in the magnitude calculation during manual Bode plotting. Specifically during the step of applying the absolute value to \$s = jw\$, what is the reasoning for why you can ...
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138 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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232 views

Bode plot graph: Frequency vs. Angular frequency

I am wondering, why are some Bode plots made with \$f\$ or frequency of signal representing x-axis, and why other Bode plots use \$\omega\$ or angular frequency of signal representing x-axis? Why don'...
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2answers
135 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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34 views

Bode magnitude computation

Consider the following transfer function $$ G(s)=\frac{1\times 10^6\, s}{s+1} $$ If I evaluate the dB magnitude analytically at frequency 0.1 rad/s, we have $$ \text{Mag. at 0.1 rad/s} = 20\, \log \...
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46 views

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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683 views

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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457 views

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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167 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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481 views

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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106 views

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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1answer
106 views

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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374 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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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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258 views

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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92 views

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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219 views

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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193 views

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 ...
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135 views

How to specify the correct phase shift of special transfer functions ?

I know how to construct the Bode diagrams of first order and seconde order(Complexe conjugate) transfer functions. But here in the two examples below i confront some difficulties. I hope someone can ...
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354 views

Draw the amplitude and phase diagram through the transfer function

My function in terms of s (Laplace variable) is: $$G(s)=\frac{1000(s+200)}{(s+20)(s+2000)}$$ The calculations I've done so far: $$G(s)=\frac{1000(s+200)}{(s+20)(s+2000)}=\frac{\frac{1000}{11}}{s+20}...
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Bode Plot Asymptotic Approach Questions

Consider the step-by-step asymptotic approach for drawing Bode plots given on the last page here. I had two questions about using this approach by hand (instead of adding individual graphs to find the ...