# Build a circuit according to a Zero-Pole plot.

Discussion in 'Homework Help' started by omar-rodriguez, Feb 15, 2016.

1. ### omar-rodriguez Thread Starter Member

Jun 24, 2015
51
2
Hello, I have to find a circuit that meets the following Zero-Pole diagram of a imput impedance:

The impedance evaluated at s= 0 is:

Z(0)=1.8k Ohm

Poles at:
P1=2.58*10^6j
P2=-2.58*10^6j
Zeros at:
C1=-2.78*10^5+2.57*10^6j
C2=-2.78*10^5-2.57*10^6j

The only clue I have is that the circuit has a resistor, a capacitor and a coil, but I don't know the topology.

I think that if the poles are imaginary conjugates then the answer has to be without loss or oscillatory, but I'm not sure, the input impedance could be this way

2. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,516
515
Your Zin(s) has s factored out. That is a problem because:
- Z capacitor is $\frac{1}{sC}$
- Z of inductor is sL
As you can see s is not factored out, so you have to rewrite your Zin(s) in such a way that you would have sL and $\frac{1}{sC}$ in it. Once you rewrite it, you will see where you have capacitor and where you have inductor.

3. ### omar-rodriguez Thread Starter Member

Jun 24, 2015
51
2
Using MATLAB, I found that I can rewrite the equation as follows:

but it doesn't help much, I was seeing if there is any similarity with the input impedance of this circuit

Last edited: Feb 15, 2016