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

Bode plot Take a typical 2nd order low pass filter amplitude response bode plot: - 3-D picture introducing pole-zero diagram Here's the bigger picture of that response when combined with a pole ...
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11 votes
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Why is frequency not measured in db in bode's plot?

Frequency is not a measure of signal amplitude or power hence, talking about "this or that" frequency in decibels makes no sense. If somebody says "increase the frequency by 3 dB"; ...
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11 votes

Why is frequency not measured in db in bode's plot?

We could start using dBHz and see how it feels. My guess is it won't make life any simpler or help understanding. NOTE however : logarithmic frequency scale is already in use, and has been for a while ...
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10 votes
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Exciting an RC Circuit at its TRUE Pole on the Sigma (Real) Axis in the Left-Half Plane

Good question, here's my attempt. You still have to convert your input signal from the time domain to s domain, then do the math, then convert the result back to the time domain. That pole just tells ...
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8 votes
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Identify zeroes of circuit by inspection

Inspecting a circuit to determine if there are zeroes is part of the fast analytical circuits techniques or FACTs as described in my book on the subject. The first thing is to place each energy-...
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7 votes
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Intuitive to get pole and zero points for lead compensator

Yes, there is an intuitive approach and it with the fast analytical techniques (FACTs). Reduce the excitation to 0 V (\$V_1=0\$ and look at the resistance driving the capacitor (you temporarily remove ...
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Low Pass Filter Wrong Pole Location

It's just a conversion from radians to degrees. The expression for a capacitor's impedance uses units of radians/sec. for frequency. The simulator is reporting frequencies in Hertz. 10 rad/sec is 1....
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Switching frequency and controller's crossover frequency in DC-DC converters

Crossover frequency selection is a bit more complex than to simply say "1/5th or 1/10th of the switching frequency" for the loop 0-dB crossover point. For a buck converter operated in ...
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6 votes

What exactly is Pole Frequency in a Filter and how does it affect the frequency response?

1) Why does the magnitude Bode Plot of the response of a filter NOT approach Infinity at a pole? Try looking at this picture and recognize that poles may exist as infinities in the bode plot but ...
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5 votes

Meaning of zeros in transfer function

1)zeros with positive real part give a negative phase contribution, reducing the phase margin (which is bad) thus limits the performance of the system. 2)Time delay in the system can also be ...
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Meaning of zeros in transfer function

There are zeros that can be located in the same region as unstable poles (that is in the right-half \$s\$-plane or outside the unit circle in the \$z\$-plane). But when zeros are out there, it doesn't ...
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Low Pass Filter Wrong Pole Location

Complex Number Diversion Complex numbers have both a Cartesian notation as well as two equivalent polar notations. The Cartesian notation, \$a+b\:i\$, is very hard to use in electronics but it is very ...
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Zeros and poles in the following bode plot

How is it possible to make transfer function to become zero or infinity. You will only get zeros and poles in the bode plot if those zeros and poles lie on the \$j\omega\$ axis. The bode plot is ...
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Why is frequency not measured in db in bode's plot?

While drawing bode's graph paper where Y axis is gain given in db while the X axis is frequency given in absolute value but scale used is log. So we are plotting log response against log frequency. ...
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Why is a capacitor to ground a low frequency pole, instead of a high frequency zero?

I intuitively expect the capacitor to cause a zero for those high frequencies, not a pole. It does create a zero but only when the frequency is infinite. For more normal frequencies (such as the 3 dB ...
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4 votes

Finding Transfer Function, Poles, Zeros of an RC Circuit

Using impedances (forgive the lack of standard forms along the way) and going long-hand from scratch, I get: $$\begin{align*} \frac{V_O}{V_I}&= \frac{R\:\vert\vert\: C_2}{C_1+R\:\vert\vert\: C_2}\...
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poles and zeroes, why the magnitude plot contradicts the actual definition

What is the intuitive way to understand this ? There is a certain amount of intuition but there's more math than intuition I would say. Below is an example I use a lot: - The top 3 pictures show the ...
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What exactly is Pole Frequency in a Filter and how does it affect the frequency response?

All depends on the variable you're using to represent your transfer function (TF). The definition of pole you know is based on using the complex variable s. Indeed, in that case you have that poles ...
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Why is frequency not measured in db in bode's plot?

Gain is relative, frequency is absolute. A dB with no reference can refer to a gain because a dB with no reference is relative. Absolute levels require a reference value to have units in dB, examples ...
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4 votes

Exciting an RC Circuit at its TRUE Pole on the Sigma (Real) Axis in the Left-Half Plane

KD9PDP's answer alreay explains very nice (+1) why the result is as you see it, but there might be an easier way to do it. You already have the impulse response (1) and the input (2): $$\begin{align} ...
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RHP zero with a positive phase shift

The correct way to write a transfer function featuring a single zero is \$H_1(s)=1+\frac{s}{\omega_z}\$ and a single pole is \$H_2(s)=\frac{1}{1+\frac{s}{\omega_p}}\$. The plus sign implies that when \...
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3 votes

The Pole Frequency of OP AMP 741

1) The 741 is ancient, even though your work might be purely theoretical I suggest forgetting about the 741 and to choose a more modern opamp, also read Reasons no use a 741 Op-amp. I'd choose an ...
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3 votes
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What is the difference between the forward transfer function and closed-loop transfer function?

I just wanted to make things a bit more clear here because it seems that the idea of open loop/closed loop/forward transfer function has got a bit mystified and does not seem exact even though it ...
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3 votes

Conjugate, non-conjugate and single poles in an RLC circuit system

The circuit you have drawn, the \$RLC\$ network, does not feature zeros, only poles. Should you add a small resistance in series with the capacitor, then you would add a zero. The equation you have ...
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3 votes
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What happens to an electrical system at its pole?

This picture might help: - Along the top of the picture there are three bode plot examples of the magnitude response for a 2nd order low pass filter. These are just examples that show how the damping ...
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3 votes

Find the Zero of a simple circuit

Well, finding the zero by inspection requires some mathematical abstraction. When you perform harmonic analysis, you only consider the vertical axis and \$s=j \omega\$. When you inspect a circuit, you ...
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3 votes

Zeroes of transfer function

Consider a simpler one-rung ladder with just L2/C4 and C3/L1/R3. Let the impedance of L2/C4 be: $$\small Z_1=\frac{a+bs}{c+ds}$$ and the impedance of C3/L1/R3: $$\small Z_2=\frac{e+fs}{g+hs}$$ where \$...
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Do we analyze real poles the same way you analyze complex conjugate poles?

I would recommend to factor the original formula in a low-entropy form and match the normalized polynomial of a second-order system which is: \$H(s)=\frac{a_0}{b_0}\frac{1+a_1s+a_2s^2}{1+b_1s+b_2s^2}\$...
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3 votes

Exciting an RC Circuit at its TRUE Pole on the Sigma (Real) Axis in the Left-Half Plane

If the system's impulse response is \$h(t)=e^{-at}u(t)\$, \$a>0\$, where \$u(t)\$ is the unit step function, and if its input is \$x(t)=e^{-at}u(t)\$, then its response is given by $$y(t)=te^{-at}u(...
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Why is a capacitor to ground a low frequency pole, instead of a high frequency zero?

You are probably mixing some meanings for the term "zero". Think of it like this: in a transfer function it represents the root in the numerator, so it "zeroes out" higher ...
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