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 ...
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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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How to design analogue compensation for SMPS from Bode Plots?
In a complicated switched mode power supply where the transfer function is unknown, is there a way to design an analogue controller and compensation from the bode plot alone? I am having difficulty ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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Nichols plot confusion
The transfer function is \$F(p)=10/(p^2+2p+1).\$
Using Wolfram Alpha, the Nichols plot shows that the argument \$\to -\pi\$ when \$\omega \to +\infty\$.
However, calculating the argument on paper ...
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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'...
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Bode plots and electrical circuits - zeroes and poles
I would like to understand electrically with little math (transfer function) involved about poles and zeroes in a control system (feedback in a DC-DC buck converter, to be specific).
I have been told ...
user220456
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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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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 ...
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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 ...
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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(...
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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 ...
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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 ...
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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, ...
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Error during analysis in AWR Microwave Office
How to fix this error, and what does it mean?
A port is off grid. All polygon edges with ports attached must be 'snapped' to the grid.
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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How to calculate the phase margin from Bode Plot if only the phase angle corresponds to the pole frequencies are given?
I have a Bode plot where only the phase angle corresponds to the two pole frequencies are given. The value of gain crossover frequency where the loop gain is unity is unknown.
$$\mathrm{PM} = \phi - (-...
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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 ...
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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 ...
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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-...
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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 ...
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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:
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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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How to make a Bode plot of an inverting amplifier?
I am trying to create a Bode plot of the open-loop gain and the closed-loop gain of an inverting amplifier using Mathematica.
I know the documentation of the bode plot in Mathematica (BodePlot[lsys]) ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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Why should 180 degrees of phase margin be considered?
We've had one feedback on the phase difference, with the gain as 1. At 300 to 60 degrees, there's just a phase difference, and at 61 to 299 degrees, the output is larger. Shouldn't we consider an ...
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Why is my LC filter Bode flattening out to 20dB/dec in my Simscape simulation?
I just made an LC filter Matlab Simulink simulation and I don’t know why the Bode diagram is flattening out.
After the resonance it falls steeply, but after that it sets at 20dB/decade. Shouldn't it ...
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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 ...
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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.
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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 ...
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How do I draw the Bode plot for this function?
How do I draw the Bode plot for:
$$ H(s) = \frac{100000(s + 10) ^3 }{s(s + 100)(s + 1000j)(s − 1000j)} $$
I searched tutorials for the Bode plot, but I can't find a solved or raw example where \$(s-j)...
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What is this functions Phase crossover frequency?
OLTF loop gain
My approach
What I have done wrong?
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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 ...
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