# 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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### 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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### 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, ...
61 views

### 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 ...
63 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 ...
110 views

### 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 ...
144 views

### About Negative Gain in Bode Plot regarding the Op-amp Circuit Design and its Relationship with the Feedback Resistor

I am new to the circuit simulation and now I am using Tina to simulate a 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 ...
• 2,687
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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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1 vote
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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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### Zero Order Hold Bode diagram

Here is the transfer function of the Zero Order Hold and its bode diagram: This transfer function is usually used for modelized a Digital to Analog Converter. Do you know why there is sharp roll off ...
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### Why is the noise gain these opamps 500? I feel it should be 250

I wanted to check the bandwidth of the first stage of an instrumentation amplifier configuration and this is the circuit: Since, the noise gain of an opamp is (1+Rf/R1), for each of the op-amps the ...
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### Is -3dB bandwidth defined for any type of transfer function?

If I have response like the following, is it still valid to say bandwidth of the circuit is 2.31kHz?
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### Please help me clear up this confusion regarding gain margin and phase margin and unity feedback

I understand the physical significance of gain and phase margin. However, I would like some clarification regarding the mathematical aspects. Videos such as the following: https://www.youtube.com/...
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### Preemphasis circuit, calculating H(s) and Bode plot

I have the following circuit: (which should represent a "new" design for preemphasis block in a FM transmitter circuit) I need to calculate the transfer function H(s) and draw a Bode plot. ... 46 views

### 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-...