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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What is minimum gain crossover frequency in bode analysis?

I know gain crossover frequency at which magnitude of open loop transfer function is 0. But what is the case here for minimum Wgc?
Swapnil sawake's user avatar
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Open loop gain of Op Amp 20 dB lower

I need some clarification regarding the open loop gain of Op Amp. I tried simulating this active BPF on LTspice. The Avol of the Op Amp U6 (UniversalOpamp) is 1meg and its GBW is 10meg. My ...
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LTspice Bode plot filter analysis

I am designing a π-type LC filter with a frequency cutoff of approximately 1khz. Simulating the filter in LTspice gives the following Bode plot. It starts dropping off at ~100hz before dropping ...
lemon's user avatar
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What is the negative omega squared in this function?

I'm trying to draw a Bode plot for the transfer function, but I am confused on what the negative omega squared is supposed to be. Is it supposed to be the frequency with no phase angle? How can I get ...
Samuel Sutphin's user avatar
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How to compensate this circuit? [closed]

I'm using the circuit above to control the common-mode voltage of the 2 resistors. M16 is a current source. The OpAmp controls common-mode voltage by adjusting the resistance of M20. I need to adjust ...
George Guo's user avatar
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Stability issue: Compensation changes using Bode plot in LTspice

I am encountering issues with a LT8390 design, particularly in higher load current conditions, which leads me to suspect a stability problem. The design parameters are as follows: vin 18-36 (28v ...
chami's user avatar
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Bode plot of a boost converter on LTspice

I'm currently learning about controller of boost converter. I tried simulating an LT3580 boost converter (5-12V) based on its datasheet below. What I did was basically copying the circuit from figure ...
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Bode plot of second order system

I'm looking for a way to do a Bode plot of the following transfer function from this schematic: I tried to find the transfer function and finally got this: \$Z_1=\frac{1}{2\pi R_1 C_1}=159\ \mathrm{...
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How do I derive a transfer function of RC circuit including ESR?

I am reading through some lecture and wondering how to derive transfer function when input source is a current source. Can you anyone give me an advice? Thank you
igor's user avatar
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Is this the correct way to get the AC transfer function for this circuit?

My approach was to put R3 and C2 to ground. Then I figured Vout is the result of a voltage divider between R4 and C2. I also figured Vx had to be a voltage divider between C1 and R3||R2. Hence how I ...
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How do I find my phase margin using the Bode plot?

From the Bode plot, is my phase margin correct? I estimate around +30 degree phase margin - or is it -30 degree phase margin? I am unsure about this thing.
Ashytone's user avatar
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Instrumentation Amplifier improper frequency response

Followup to this question. I have an instrumentation amplifier. When conducting an AC Sweep, this is the response. There are two issues with this. Firstly, the signal magnitude is far too low. ...
HFOrangefish's user avatar
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Bad AC response from bridge circuit

Followup to this question. Hi. I have the following bridge circuit to simulate a strain gauge. I am conducting an AC sweep of it as another part of my circuit (currently disconnected) that uses the ...
HFOrangefish's user avatar
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Control engineering: how to design a system for desired impulse response

I've designed a system to get a desirable step response. However, I think the impulse response of my system is more important. There are many methods for designing a system for transient response ...
Mr Phase Locked Loop's user avatar
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Inverting opamp amplifier: frequency response not compatible with LTspice simulation

I have a simple inverting opamp amplifier and I want to study the frequency response of the circuit and finally calculate the frequency band (or cutoff frequency). Unfortunately the model created in ...
Gabriele's user avatar
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How to reduce gain margin to finite value?

I am trying to observe bode plots for a system but i am getting infite gain margin. I know that positive phase margin and/or positive gain margin represent stable system while negative phase margin ...
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Unable to find Gvd of a buck converter using LTspice

I'm trying to simulate a closed-loop buck converter in LTspice. I'm using ideal components. I started by finding the Gvd of the buck converter (duty to output transfer function). I used the .ac ...
Aditya Bhalerao's user avatar
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Discrepancy Between Bode Plot Predictions and FFT Output for Higher-Order Low Pass Filters on a 10 kHz Square Wave

I have conducted an experiment where a 10 kHz square wave is input through low pass filters of 1st, 2nd, 3rd, and 4th orders. After passing the square wave through these filters, I observed the FFT (...
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How is the number of crosses of -180 line calculated from the bode plot?

On the page 28/46 of the slide here: On the page 42/46: How are N_ and N_ equal to 1/2 here? I think it should have been N_ = 0 and N+ = 1.
internet's user avatar
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Magnitude ambiguity of a signal with a frequency equal to system pole in unit-less plot and Bode plot

Suppose we have a first order system (H(s)=1/(s+p)) having a pole at s=-p. Now, to this system we are passing a sinusoidal signal having a frequency same as the frequency of the pole. Since H(s)= 1/0= ...
Arindam Maulik's user avatar
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Linear line on loglog plot

I'm trying to plot a -20dB/dec line on MATLAB but can't seem to get it correct. I know that a linear line in a loglog plot is actually an exponential curve in the linear scale. So writing a y = mx + ...
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In Bode plots what does phase tell us for passive filters (open loop)?

I was just playing around with a passive filter to erase some noise - one that should work between 80MHz and 1GHz. I'm aware that the phase in Bode plots gives data about the time delay between the ...
user67441's user avatar
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Why is the current source type/waveform influencing the ac analysis in ltspice?

As I understood the ltspice .ac analysis, it would linearize the circuit and solve it with an AC stimulus in the source marked with "AC 1" ( which then ...
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Bode Plots and Transfer Function

How would you find generic form of this transfer function given these bode plots? I am having a hard time since the phase angle "dips" instead of going up.
Roy Hwang's user avatar
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How to get the transfer function out of a Bode Curve on a datasheet?

I am trying to find the transfer function of AMC1350 out of its datasheet. I dont have any information about which degree of a lowpass filter or what kind it has. DC gain is 2/5. Cutoff frequency is ...
Emre Mutlu's user avatar
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Why does MATLAB show a pole in bode plot of an underdamped second order system at natural frequency?

I am using the sisotool in MATLAB to obtain the bode plot of the following transfer function: MATLAB marks a pole at wo which is approximately 11.18 What is the meaning of this? How would you even ...
needbrainscratched's user avatar
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Assign Bode plots to Nyquist diagrams

How do I assign the following Bode plots to their corresponding Nyquist diagram? Can i tell the number of poles of the transfer function of the nyquist plot, by looking at w→infinity (from which of ...
insertRandomName's user avatar
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LC filter out of the loop if crossover frequency is below resonant frequency?

Referring to slides 78-84 of http://powersimtof.com/Downloads/PPTs/Chris%20Basso%20APEC%20seminar%202009.pdf, the RLC network rings alone and the oscillations are not due to the loop. It is my ...
Hyp's user avatar
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Are RC /CR - Highpass filter the same?

I‘m quite new to electrical engineering and one of the tasks is to showcase and plot an CR high pass filter. I am familiar with RC HP filters but this is new to me. Just changing the order of the ...
LostMemories's user avatar
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How to find the Transfer Function of this circuit?

I am trying to find the transfer function of this circuit, but I can't find how. Does anyone have a clue?
thefrenchy2706's user avatar
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Calculate the Transfer Function of an AOP circuit

I am trying to calculate the transfer function of this circuit. Does anyone have an idea about it? Image source: Analog Devices - Circuit Note CN-0276 - part of Figure 2. Excitation Driver and Filter ...
thefrenchy2706's user avatar
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Estimation of bode plot of closed loop system based on open loop characteristics [closed]

I just got an exam back in which I did the error of not drawing the phase part of the bode plot of a closed loop system. The question sparked, how does one estimate the shape of the phase plot of a ...
Luka Pacak's user avatar
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Stability with phase dip

In https://www.analog.com/media/en/technical-documentation/data-sheets/13756fd.pdf referring to this figure it says Why is this not a problem? My reasoning would be: phase gets close to 0°, so the ...
Hyp's user avatar
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Does the idea of bandwidth make sense for a system with an infinite DC gain?

I'm thinking specifically of systems with ideal PID controllers. The transfer function will always have an integrator term, which, if I understand correctly, means it will always have infinite DC ...
Mikayla Eckel Cifrese's user avatar
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248 views

Negative damping ratio for second order transfer function

For this circuit: We get this transfer function (this is the solution of another student, but I did it by hand and I get the same thing): Where the first damping ratio is negative. I read on another ...
c.leblanc's user avatar
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5th order filter transfer function poles and stability issues

I have 5th order filter circuit as shown below. But I am trying to find a mathematical expression to calculate the values of inductances and capacitors. Using Wolfram-Mathematica, I found Iout/Vin ...
analog_designer's user avatar
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How do I find gain values between decades on asymptotic Bode plots?

I was doing some past exams for my control theory final and came across a question with the following asymptotic Bode plot given: In order to solve for \$ \omega_c\$, I need to essentially find the ...
Ahsan Yousaf's user avatar
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Why a series resistor on the output of an op amp would add a zero

Capacitance on the output of an op amp I was looking at this post and I totally understand except the answer said that the series resistance at the output of the op amp is creating a pole and a zero. ...
Wu Eric's user avatar
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How could we predict the transient response of the multi-loop circuit?

Typically, when analysis the stability of a single loop circuit, we can use the open-loop method, just to break the loop and get the loop gain. Then, using the Bode diagram, we can easily get the PM(...
hideinink's user avatar
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Is there a correlation between conditionally stable systems and non-minimum phase systems?

I know bode plots cannot be used for non-minimum phase systems ( eg: delay, Boost converters). Can we identify the closed loop conditional stability from open-loop bode plot response? Conditional ...
Dynamic_equilibrium's user avatar
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Is it correct to use the concept of phase margin for not so 'well-behaved systems'?

The TI document mentions the Phase margin as 60 degree for the given bode plot whereas the lowest PM when Gain >1 is around 45 degree. Wiki says: " Ordinarily, as frequency increases the ...
Dynamic_equilibrium's user avatar
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Why do we prefer a cross over slope of -1 (20 dB/decade) for bode plot of power converters?

The video mentions (@12:45), we should ensure the slope at cross over should be around -1 (20 dB/decade). He mentions we can apply phase margin test if this condition is satisfied. As far as I know we ...
Dynamic_equilibrium's user avatar
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Frequency response measurement of power converter - Why is the injection point across the resistor?

The standard procedure of measuring the frequency response of a buck converter is to inject a small voltage across a small resistor Rt as shown below. (Ref @4:40) Why do we apply the input voltage ...
Dynamic_equilibrium's user avatar
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Boost average current mode control

I have one question about the bode plot of boost average current mode control. Below is my schematic, the circuit is stable. My design is for CCM boost PFC, and the current loop crossover frequency ...
Power JJ's user avatar
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What is the phase margin of this inverting amplifier?

I'm having trouble finding the phase margin the telescopic cascode amplifier I'm currently building. This source says that the phase margin for an inverting amplifier is the distance from -360 degrees ...
snowball's user avatar
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How to obtain a bode plot for this circuit in Matlab online version

So I've an electrical circuit in matlab as follows: I've already setup the points of linear analysis. But I can't the option for linear analysis in the linearization tab. The problem is that I cannot ...
Zipho Lunika's user avatar
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LTspice Bode plot is incorrect or inconsistent (op-amp circuit)

I'm testing the open loop transfer function of an op-amp circuit by following this schematic: This is my LTspice schematic (keep in mind the actual op-amp circuit itself has been thoroughly checked, ...
lostduck's user avatar
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Bode plot of second-order system

I was reading about second-order systems in Control systems engineering by Norman Nise and I am confused by the idea that the phase at high frequencies of a second-order system is equal to 180° (check ...
tonyjk's user avatar
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Why do we talk about system stability as a whole when Barkhausen criteria is valid only for one specific frequency?

The relationship AB=1 will be applicable only at a specific frequency. For instance, following is the bode plot for a circuit I have and as can be seen, the barkhausen criterion is met only at 6.3MEG ...
needbrainscratched's user avatar
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Frequency response of LC filter with resistance in parallel with the capacitor

The following is the diagram of interest: The impedance of the filter is: $$Z_o=\frac{R_f L_f s}{R_f L_f C_f s^2+L_f s+R_f}$$ and the bode plot with all different components and the total impedance ...
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