# 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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### 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 ...
81 views

### What information Bode plot does NOT present?

The classic Bode plot (2D Bode) represent value of the transfer function (a complex number) evaluated at $j\omega$ (imaginary axis). It provides information on system closed-loop stability margins ...
76 views

### Do we analyze real poles the same way you analyze complex conjugate poles?

So I am analyzing a filter and I came up with the following expression for the transfer function in its canonical form: $$\frac{987654 + 4666.67 s + 1. s^2}{2.48519 \times10^8 + 52316.2 s + s^2}$$ ...
87 views

### What is the bode plot of an inverting op amp if you replace the resistors with caps?

What is the bode plot of an inverting op amp if you replace the resistors with caps? What if you now add a capacitive load to the output? Update: I ran a quick simulation and the bode plot looks as ...
45 views

### Why bode plot of cascade system is not the sum of subsystems?

I have two subsystems which the transfer functions you could see below as g(s) and h(s). According to some references show below, I found that the bode plot of a cascade system should be the sum of ...
63 views

### Differentiator cut-off frequency

A practical differentiator has two cut-off frequency but can no longer perform differentiaiton after first cut-off. After first cut-off there is a 20db per decade gain reduction but why does this ...
36 views

### KHN biquad: why does LTSPICE plot a wrong phase plot for bandpass filter?

I'm studying the KHN biquadratic section and its outputs to obtain a lowpass filter, a highpass filter and a bandpass filter. I simulated the filter using Mathematica and obtained the following plots, ...
48 views

### 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 ...
73 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 ...
445 views

### Transfer function of electrical network

I need help with this problem. The transfer function that I found is ((RCS+1)/(2RCS+1)) , but then I cannot go further because the form of T.S is untypical. The typical form of this question is RC ...
121 views

### How to do the bode plot for this function without Matlab?

I want to plot the bode diagram without any software for $$G(s)=\frac{(s-2)}{(s^2+4s+15)(s+2)}$$ I do not know how to deal with the factor of $s-2$ I will be appreciate if someone can show me your ...
132 views

### Zeros and poles in the following bode plot

According to the definition, zeros are the frequencies which make transfer function to be zero, and poles are the frequencies which make transfer function to be infinity. The definition can be seen ...
40 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 ...
42 views

### Bode plot display in matlab

I would like to display a bode plot of a buck-boost converter using Matlab, so I got the figure shown below, If we look closer to the phase plot, we see that it starts from 360°. My wish is to make ...
44 views

### Determine output filter using the bode approximation

Given that the carrier frequency Fc and modulation input frequency Fm are known, how would I use the bode approximation to determine an output filter, if the carrier frequency component must receive ...
70 views

### Verification of Sallen Key Design

I have designed this Sallen-Key to give a 2nd order low pass circuit with a cut-off frequency of 150Hz. Another design specification is that R1=R2 and C1=C2. The issue is when simulated on LT-Spice ...
82 views

### How can I find the drain transfer function of a MOSFET on LTSpice?

I am trying to get the drain transfer function of a MOSFET by setting the drain to source voltage as the input and the gate to source voltage as the output. I created the following circuit in LTSpice: ...
27 views

### how to plot on the same bode plot a manual function plot() with function bode()?

I have a a transfer function that I plotted manually using Plot(w,abs(f1(w)))(plotted for a digital filer since I dont have signal toolbox) and I have another function that I used directly bode(f2(s))(...
54 views

### Plotting a bode gain plot with the slope in Excel

I am not an expert in Excel, and therefore, I want to know if there is a way of including the slope (dB/decade) in a bode gain plot in Excel or any free software (that allows to first input the ...
39 views

### How to visually determine the damping ratio when we know the peak amplitude

I am currently trying to understand this example from the book, where it visually calculates the dampening ratio given the peak amplitude as well as the natural frequency. Here is the graph from which ...
42 views

### How to choose the transfer function?

Greetings from a physics student. I have to do an activity which aim is to design a filter in frequency. To do so, I need a transfer function (gain, poles and zeros) that must meet the following ...
102 views

### Help deriving the transfer function of an LC circuit?

I have the LC circuit below. I believe (but I'm not certain) that this is a 3rd order filter. Since there are two capacitors and 1 inductor. The circuit is a passive low pass pi filter. The ...
60 views

### What does 'passband phase' and 'stopband phase' mean?

I've been provided with a Bode plot for an RC filter circuit with a cutoff frequency of 10kHz. Im asked to find the stopband and passband phase from the graph. I'm confused how these can be just a ...
39 views

### 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'...
1k views

### What does a Bode plot represent and what is a pole and zero of a Bode plot?

I studied Bode plots and the author of my book is somehow relating zeros of transfer functions to Bode plots. What is the relation between zeros or poles of a Bode plot and transfer function? We ...
181 views

### How to find the cutoff frequency of an underdamped second order lowpass filter

I've learned that for a first order LPF the 3dB frequency is one where the amp's gain is (surprise) -3dB below the DC gain. However, on a second order LPF that is underdamped we get a "peak" at around ...
73 views

### Poles from Bode plot

How does one deduct the number of poles from a Bode plot? Is it further possible to decide where the poles are? I have not understood this concept even though there is so much focus on Bode plots in ...
39 views

### 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,...