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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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Butterworth Filter attenuates noticeably in pass-band

The Issue: I am using a Maxim MAX7480 8th order Butterworth low-pass filter to counter any aliasing from a sensor that measures signals up to 3kHz, but I only want up to 1kHz. Thus a critical ...
Daniel Godø-Dempsey's user avatar
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Where is the origin pole in my CM buck SIMPLIS ac simulation?

I know that current mode buck regulators are generally stable as long as they're actually operating in current mode (i.e. the inductor ramp current is large enough to prevent slope compensation from ...
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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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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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Underlying reasoning behind lead and lag nomenclature of compensation

If \$0<z, \;p\$, the Laplace transform transfer function \$\frac{s+z}{s+p}\$ constitute two distinct types of compensators. If we look at this schematic, \$0<z<p\$ (lead compensation) implies ...
kbakshi314'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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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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Optimum design of damping LC filter with parallel (R+C). There is a frequency in which value of R dosn't impact

Apologies for the not so clear title, but I don't know if there is a common phrase that describes the point of concern. I am taking an online course about input filter design interfacing the grid and ...
amidher's user avatar
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What are the gain and phase margins from this Bode plot?

I thought I had a decent grip on how Bode plots work yet for this model that I am working on, I need to implement a lead or a lag compensator. A lead compensator, which I was thinking about ...
johnny_yes_papa's user avatar
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Is it okay/valid to have a Bode plot that has linear magnitude scale?

I have almost always seen that the magnitude axis of a Bode plot is in dB but today I was shocked when I saw in LTspice that Linear option was also available for Bode representation. I am very ...
user303520's user avatar
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Is there a methodical way to desig multi-stage anti-aliasing filters?

Lately I've been thinking about the best approach to design multi-stage anti-aliasing filters in real-life. I know tools like Analog Filter Wizard or LTSpice can help to a certain extent, but they've ...
davidanderle's user avatar
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MOSFET Differential Amplifier Bode Plot

I've created a MOSFET Differential Amplifier in PSpice, the schematic of which I've attached. However, when doing an AC sweep and adding a trace to do a Bode plot, the graph is a flat line, and I don'...
wclabs's user avatar
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Resonant circuit using LTSpice

I'm a college student and I was supposed to draw the Bode-plot of the following resonant circuit. I obtained this. My questions are: shouldn't I have obtained a bell-shaped curve? How can I find the ...
Gloria's user avatar
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power supply frequency response

I have a question regarding the frequency response of a boost converter. I am curious to know what causes the "blip" at around 8kHz that causes the response to go up and then back down. At first, I ...
suzu's user avatar
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Stability analysis - 0 dB crossover point

I have a question about Bode diagrams. For example if a Bode plot (gain) cross 2 time the 0 dB axis which point should we consider. Should we analyse both of them and keep them stable (good phase and ...
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Plotting the bode plot of a high pass filter using matlab

I am trying to theoretically find the frequency response of the circuit given below: Firstly i found the impedance value of the RC Ladder by applying the equation below, then i defined this as "...
Neverhadagf's user avatar
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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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2 answers
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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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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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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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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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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 + ...
SM32'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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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 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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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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1 answer
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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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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 ...
amidher's user avatar
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LTI system Bode curve

Given an RLC circuit, I needed to find the transfer function, which I did. Now I need to find R and L so that the next two conditions are met: The overshoot is 25% The first peak time is t = 3 The ...
Math king's user avatar
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Negative loop gain of LDO

I am trying to design an LDO with the following specification: Vout = 1.5V; Vin = 1.7V - 2V; Iload = 75uA to 1200uA. However, while I am simulating its loop gain, its gain is coming negative. Even ...
Noob Coder's user avatar
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Frequency response of a cascade opamp circuit using LTSpice

I'm trying to simulate this circuit which consists of multiple stages of op amps, but I couldn't figure out the operating bandwidth of the circuit. Using AC analysis, the Bode plot is a weird shape ...
Jacob Sebastian's user avatar
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94 views

Gain and phase margin interpretation in control system

I have a unity feedback system with the open loop transfer function having the following bode plot: As shown on the plot, the gain margin and phase margin are -27.4937dB and 75.0185 degrees. And the ...
Hadi Amrat's user avatar
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364 views

Gain crossover frequency in bode plot for control system

I know that gain crossover frequency (freq at which gain is 0dB) is where the phase margin is calculated. I also know that the gain crossover freq must be lower than phase crossover freq for stable ...
John.Apple's user avatar
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99 views

How to plot uncomensated loop gain in LTspice

I want to plot an uncompensated loop gain of a dcm flyback dc-dc converter. I know that I can derive the control to output transfer function and then plot the uncompensated loop gain but that just ...
tinkerer's user avatar
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748 views

Visually determine pole from Bode plot

Currently I'm taking a basic electronics course and this was a part of homework. The Bode plot represents the frequency response of an amplifier and from this plot we had to determine the dominant ...
Mark's user avatar
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Phase lower than -180 when reaching unity gain, is it unstable or can we substract 360?

I am getting a phase of -434 degrees when reaching unity gain (0 dB point). The phase curve starts at 0 degrees, thus, can we consider that -434= -434+360= -74 degrees and the phase margin is of 180-...
Martin Delaverge Douce's user avatar
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169 views

Which of the following methods tells Absolute stability & which method tells Relative Stability? Bode Plot, Routh Hurwitz, Root Locus, Nyquist PlotC

Which of the following methods tells Absolute stability & which method tells Relative Stability? I. Bode Plot ii. Routh Hurwitz iii. Root Locus iv. Nyquist Plot What i think is the following ...
Husnain Afzal's user avatar
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1 answer
108 views

Plotting a Bode from a Transfer Function on Matlab

I need a bode plot for a transfer function from matlab which I never did before. I tried some examples but failed. How to do this on matlab? Here is the TF:
Das D.'s user avatar
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Is there an alternative to GCV (generator control voltage) to synchronize frequency sweep measurements?

A friend is taking a course in electronics engineering and asked me for help reproducing a lab experiment in frequency sweep measurement techniques. Students build a small RC filter and use a function ...
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Oscillation frequency / criteria from Bode plot, negative feedback system

Got a question, which is very integral to a project that I am writing a report for (which I am to hand in soon, so in a hurry). Question: What will my oscillation frequency be? How will it be ...
David skovgaard hansen's user avatar
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0 answers
134 views

Bode plot acting weird with specific op-amp

Hello why is the behavior of this op-amp so weird (OP177).I simulated another op-amp(uA741) with the same biasing and the bode plot looks fine(still i dont get the 80dB amplification i would like, yea ...
Mixera4's user avatar
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Having trouble making transfer function from this Bode plot from op Amp datasheet in Mathematica

I am fairly green to control theory. I am trying to reproduce the Open loop transfer function of the LT1X28 op amp in mathematica. I want to get the poles and zeros from the following plots and ...
Josh Girgis's user avatar
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109 views

Why is Δt constant in phase shift measurement?

I would like to ask for some help with phase shift plotting. To be precise, with time delay between two waveforms. I am measuring two currents using an oscilloscope. channel A (blue) is my current ...
Wintermute's user avatar
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57 views

Phase margin plot of LDO

For this LDO circuit design at https://github.com/promach/LDO/tree/development , 1) which exact circuit node(s) contributes to the zeroes near 1MHz after removing CL ? 2) If I remove "AC 1" from ...
kevin's user avatar
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Octave bode plot looks like a decade plot in LTSpice

When I do a bode plot on a load over a simple LRC filter then compare graphing the frequency in OCT and DEC, I would expect their plot shapes would look different given OCT plots the x-axis in 1Hz,2Hz,...
KMC's user avatar
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1 answer
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How to determine the transform function of certain bode plots?

The answer to this question above is C, yet I only know that the anti-resonance and resonance are located at 8 and 11 Hz respectively. Another example below to which the answer is B. I appreciate ...
Setting Fires's user avatar
0 votes
2 answers
176 views

Drawing the Bode Plot of a loop gain

Below I have the loop gain and the Bode plot for it, however I do not understand the phase plot. Why does it start at -90 degrees instead of 90 degrees since we have a zero? Please explain.
Hector's user avatar
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Error amplifier in PWM controller

Using the datasheet UC3842 PWM Controller I have modelled error amplifier in it. AC analysis of error amplifier matches with the datasheet plot(Figure 3) - Since I need to clamp the output ...
Pai's user avatar
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What is this functions Phase crossover frequency?

OLTF loop gain My approach What I have done wrong?
SUNITA GUPTA's user avatar
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2k views

How to find Phase crossover frequency?

I make the imaginary part of \$loop \ gain=0\$ to find phase crossover frequency. But in one video, the person told that this method can only be applied when Polar plot crosses the real axis and ...
SUNITA GUPTA's user avatar