Problem with Pole zero analysis using multisim

[sagar_vanarase]

Problem with Pole zero analysis using multisim

When I tried to find input impedance function's pole zero of a parallel LC network using Multisim
pole zero analysis, I get following message
"
...........

| | doAnalyses: matrix is singular
| |
| |
| | pz simulation(s) aborted "

The circuit as well as log file attached.

How to correctly perform pole zero analysis?

[OStep · Accepted solution]

Part of performing a pole/zero analysing is linearizing the circuit using a DC operating point analysis, in which an inductor acts as a short circuit. The problem is that in your circuit, the inductor is in parallel with a voltage source internal to the function generator.

Use a small resistor (1mOhm will do in your case) in series with the function generator output to break the short circuit loop.

[sagar_vanarase]

dear sir,

thanks for your earlier reply to my question on pole zero analysis

one more problem on pole zero analysis ;

i tried to do pole zero analysis for circuit(shown in attached file where C1=1/6F(167mF) C2=5/18F(278mF) for which

z(s)= (s^2+9)(s^2+1)

         ----------------------

           s(s^2+4)

for which zeros are at  +/-3j ,+/-1j

              poles at       0 ,+/-2j          as per theory:

But multisim gives different values (shown in attached file)

what is the problem?

please clarify.

thanks & regards

sagar vanarase