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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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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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 ...
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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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Phase response in MATLAB simulation doesn't match the book
I am trying to replicate a result from a textbook that I am using to study input filter design for buck converters.
The parameters for the converter and filter are as follows:
D = 0.5
L = 100 μH
C = ...
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Reading transfer function values from Bode plot
I am trying to get back into control systems and at the moment I am stuck on how to extract the damping ratio and gain from the Bode plot I generated.
Firstly the gain. As far as I can remember the ...
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Meaning behind DC/DC converter frequency response
I am currently reading an article about control methods of DC-DC converters
which contains the following diagram:
This diagram seems to show the magnitude (gain) and phase of the output signal
of the ...
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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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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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Why do LC filters have 40 dB/decade ripple attenuation at high frequencies?
I am taking an online course on power electronics in which I encountered the following concept which I couldn't understand.
The instructor had the following comment about the following grid interface ...
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How to determine the phase margin when the Bode plot never crosses 0 dB?
I have a graph that looks like this. I am tasked to measure the phase margin, but the graph doesn't exceed 0 dB.
The circuit is this. The input DC level is 0.6 V, which is the problem. When I change ...
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Why can the Bode plots of transfer functions have negative magnitude values?
I am currently learning about Bode plots and transfer functions. I am confused about what information the "magnitude" values of the transfer function are supposed to contain. I am mainly ...
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Confusion regarding bode plot?
I am trying to understand bode plot and i came across attached snap especially black solid line in magnitude plot, i captured this snap from wikipedia. Here i am confused,what is cutt off frequency? ...
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How to design filters with transfer function?
I want to design filters base on transfer function and Bode plots. For example, lets say I want a low pass filter, the limit is 36hz. How should I design a transfer function base on 36 hz limit? (pls ...
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Double pole, double zero: incorrect plot?
I can't seem to find where I'm going wrong here. Suppose I want a double pole, double zero system that looks like this:
$$ \dfrac{\left(1+\dfrac{s}{\omega_z}\right)\left(1+\dfrac{s}{\omega_z}\right)}{\...
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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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Phase shift of an ideal op-amp integrator
I derived the transfer function of an ideal op-amp integrator and calculated the phase response of the Bode plot. My own derivation matches the result of this website.
This means for the transfer ...
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Bode phase plot phase margin
From what I have studied so far, gain margin is defined as how much additional gain the system can be given before it becomes unstable, and this can be measured from the bode magnitude plot ...
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Finding resonant frequency and cut-off frequency from Bode plot to calculate values for RLC circuit
I am trying to find RLC values from a Bode plot. I have a band-pass filter from a transfer function and have put arbitrary values for the RLC components in Matlab.
I am unsure how to mathematically ...
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Why does the Bode plot in LTspice disagree with my command calculation?
I am trying to use LTspice to plot Bode plot for frequency response. I used command to get the gain at the 1kHz first. In the error log it turns out that it is 47.3dB.
When I used small signal AC to ...
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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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Why are there ripples in the passband of some filters, like the Chebyshev filter?
Please see the Bode magnitude plot as we steadily increase the input frequency to the filter. Why does the magnitude oscillate? What physical component(s) in the filter circuit is producing that ...
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How is gain margin defined for this control system?
Lets say there is a system
H(s) = 3/s
which I want to control with a controller
G(s) = Kp·(1+10/s)
The Bode diagram of the open loop G(s)H(s) with Kp=1 is:
At the transit frequency the phase is ...
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What does the value projected on the σ axes mean in s plane?
This question is related to my last post. To avoid confusion, I opened another question.
From a website that John shared in my last post, this is a plot that is a 3D picture combining the Bode and the ...
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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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Bode plot from s-domain singularities
Considering any transfer function H(s), is there any meaningful way to use the s-variable singularities to obtain the f-variable ones to trace the Bode plot?
I know direct conversion with \$ s = \...
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How to correctly measure the bandwidth of an amplifier with gain from its bode-plot?
I have an amplifier with the following frequency response:
It is an inverting amplifier with a gain of about -12. I would like to know what would be the correct approach for identifying its bandwidth....
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Unclear relationship between s domain and frequency domain
I’m trying to brush up on some things I left behind, let’s consider the usual RC parallel circuit, I’m trying to get the bode plot of its impedance.
The equivalent impedance is obviously \$ Z = \frac{...
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0 dB Bode plot as a reference in an academic paper
I want to compare the calculated bode plot of an inverting op-amp with the simulated one, on the 1 mHz-200 kHz spectrum.
As expected, theoretically there is no stray capacitance on the circuit above, ...
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Stability in a double-pole system
A simple low-pass RC circuit is a single pole system and it's stable. In a DC-DC buck converter, we have a conjugate double pole due to the LC filter. Yet, we employ several techniques such as D-CAP ...
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My bode plot does not mach with calculated cut-off frequencies
I have modelled a band-pass filter, but when I calculate the cut off-frequencies and amplitude it does not match with the bode-plot. I am not able to find out what is wrong, hope that someone might ...
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Bode diagram cutoff frequency in LTspice [closed]
My question is about the cutoff frequency of Bode diagram.
In the output of this circuit I got this bode diagram normally. When I read the cutoff frequency on -3 dB. But here I don't have -3 dB. ...
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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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Finding transfer function from Bode plot
While I know how to find the transfer function from the response graph, I don't know
how to find it from Bode plot.
What I know about the system:
The system is a second order system
The system has no ...
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Confused regarding gain margin and stability
I plotted the bode plots of the transfer function:
G(s)= 2.123×10^6 ((0.105s+1.01))/(s^2 (s+12566.37) )
It is as follows:
As can be seen, it shows the gain margin as negative infinity, however loop ...
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4th order low pass Butterworth filter with very low Q factor [closed]
I have designed a 4th order low-pass Butterworth filter with a 0.707 Q factor. However, what I am getting is almost no flatness in the pass band region and my frequency response looks like a half of a ...
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What will be the values of phase crossover frequency when the gain margin is infinity?
$$G(s) = \frac{s+1}{s^2+2s+100}$$
For the given transfer function I am getting the gain margin equal to infinity in the matlab, but i am not getting the value of phase crossover frequency.
What will ...
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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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Q: How to read this bode plot to find transfer function?
I am working on a blackbox system and I would like to make a Bode plot to find its transfer function. Since I do not have a lot of information on the system I am trying to input a series of sin waves ...
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About negative gain in Bode plot regarding the op-amp circuit design and its relationship with the feedback resistor
I am new to circuit simulation and now I am using Tina to simulate an op-amp circuit for a photodetector. I have some questions regarding the Bode plot.
Below is the circuit design, based on the ...
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What's the physical significance of a sinusoid's Bode magnitude?
What's the physical significance of a sinusoid's Bode plot's magnitude, at the sinusoid center frequency?
Example: sin(wt), with w = 62.8 rad/s = 10 Hz. This has ...
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Why does a loop gain phase margin plot start from 180?
Bode plots are used to plot the the magnitude and phase of the loop gain - the mulitplication between the feedforward gain and the feedback factor, nothing else.
Why do some plots start at -180 and ...
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Unstable system in s-plane but stable on bode plot?
I am reviewing bode plots and s-plane (pole-zero plots). I seem to have some confusion about them and how they relate to each other. I believe one is for closed-loop systems, the other is for open-...
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Frequency domain design of a PI controller for a first order system with transport delay
Let's say I have following first order system with transport delay
$$G(s) = \frac{4563}{s + 64.77}\cdot e^{-0.000455\cdot s}$$
My goal is to design in the frequency domain a PI controller in the form
$...
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Bode Phase Plot for negative transfer function
My question is relatively simple. Supposing that we have a transfer function of the type \$\frac{-Kj\omega}{\omega_0}\$. Then for the phase Bode plot, I should start from \$\pi\$ and then add \$\frac{\...
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How to recognize a non-minimum phase system from the Bode plot?
I have a bode diagram and I have to obtain if is it a non-minimum phase system or not.
I think we could obtain zeros and poles from the Bode diagram but I'm looking for a fast way to find the answer.
...
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Using an oscilloscope to measure the gain of an op-amp circuit (with capacitors)
I have an upcoming laboratory exam where we have to construct an op-amp circuit (from our experiments the circuits were always varied and probably will be a bit more difficult on our exam.)
We are ...
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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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