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.

Filter by
Sorted by
Tagged with
1 vote
3 answers
109 views

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 ...
  • 395
3 votes
3 answers
94 views

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 ...
  • 199
0 votes
0 answers
53 views

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 ...
1 vote
2 answers
75 views

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 = \...
0 votes
3 answers
63 views

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....
0 votes
1 answer
52 views

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{...
  • 15
0 votes
2 answers
110 views

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, ...
-1 votes
1 answer
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 ...
  • 15
2 votes
2 answers
62 views

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 ...
-2 votes
2 answers
67 views

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. ...
  • 45
0 votes
0 answers
46 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 ...
0 votes
0 answers
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 ...
3 votes
1 answer
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 ...
0 votes
2 answers
86 views

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 ...
-1 votes
1 answer
135 views

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 ...
-1 votes
1 answer
126 views

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 ...
4 votes
0 answers
73 views

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 ...
0 votes
1 answer
67 views

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 ...
  • 1
2 votes
1 answer
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 ...
-1 votes
2 answers
82 views

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 ...
  • 3
-1 votes
1 answer
230 views

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
0 votes
2 answers
145 views

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-...
  • 2,687
1 vote
2 answers
169 views

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 $...
  • 885
0 votes
3 answers
94 views

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{\...
0 votes
2 answers
235 views

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. ...
4 votes
1 answer
256 views

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 ...
  • 173
1 vote
0 answers
65 views

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 ...
0 votes
1 answer
116 views

Stability of the op-amp?

I am confused if the below amplifier will be stable or not when it acts as unity gain amplifier ( with a feedback factor of 1) ? My analysis: PM = zero from the bode plot , so the system is stable ! ...
0 votes
2 answers
63 views

LTSpice: represent group delay when x axis changes

I am trying to plot the group delay of the following circuit. Usually it is enough to change the y axis from phase to group delay. However because I changed the x axis to represent a normalized ...
2 votes
0 answers
57 views

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 ...
  • 145
0 votes
4 answers
69 views

How to verify the voltage and frequency response in a simulated equalizer?

I am working on a simple equalizer, intended to filter bass, midband and treble frequencies. I'm wiring the bode plotter of Multisim in a wrong way,perhaps. The circuit is: The idea is to measure the ...
  • 510
0 votes
1 answer
153 views

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 - (-...
2 votes
1 answer
87 views

Difference in Bode plot with table and Bode plot in Matlab

I am trying to generate a Bode plot for a transfer function of a high pass circuit. It's part of a solution to another question but this is the part that is confusing me. I have a transfer function: ...
0 votes
1 answer
142 views

Why this overshoot in transient?

I am designing a forward converter whose output can be variable from 4V to 30V, 0-5A. This is going to be a pre-regulator for a linear converter. This is the schematic: I am using UC3844 controller ...
  • 170
0 votes
1 answer
67 views

Can any one explain what type of compensation is this

I will be using the UC3844 controller IC in combination with TL431 to achieve peak current mode control in a 150W forward converter. After some research, I found this schematic on the internet: There ...
  • 170
0 votes
0 answers
52 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 ...
  • 170
0 votes
0 answers
169 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 ...
  • 31
-1 votes
1 answer
66 views

Designing a bode diagram circuit

I have realized some low pass filters with a nominal cut off frequency around 10kHz, which I will use in combination with other filters to eliminate noise on DC and quasi-DC signals (around 30Hz). I ...
  • 3
0 votes
1 answer
162 views

Transfer function of an op amp with an Y or delta

What's the transfer function of the op-amp with a Delta from figure one? Such circuit can be easily converted into an Y, figure 2. Tina is calculating the transfer function from the Y circuit as H(s) =...
1 vote
1 answer
120 views

How to find damping and the natural response in a system with a zero and complex pole pair

I want to know how to get damping and the natural response in a system with a zero and complex pole pair. I calculated the following transfer function: (from an active filter composed of 2 capacitors ...
0 votes
1 answer
59 views

Identifying transfer function by its approximated graph

Consider the transfer function which is approximated graph is: I want to identify this function. As far as I can tell, since we see decreasing by \$-20db/dec \$ at \$10^{-1}\$, we can conclude that ...
1 vote
0 answers
62 views

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 ...
2 votes
2 answers
418 views

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 ...
  • 1,500
0 votes
1 answer
80 views

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 ...
3 votes
4 answers
949 views

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?
0 votes
1 answer
144 views

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/...
2 votes
1 answer
120 views

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. ...
user avatar
0 votes
0 answers
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-...
0 votes
1 answer
58 views

Bode Plot of Type 3 Compensator

I've designed a Type 3 compensator and wanted to see it's bode plot on matlab. Here is the transfer function of type 3 compensator: My values are: wp0=203 wp1=6657000 wp2=31400 wz1=5024 wz2=5024 The ...
  • 131
0 votes
0 answers
68 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 ...

1
2 3 4 5 6