AnsweredAssumed Answered

Cayenne simulation result was incorrect

Question asked by twp on Nov 29, 2011
Hi There,

I've a circuit with the following connections:

AC Voltage Port ( 13.56MHz at 10Vac amplitude, R=50Ohm ) connecting in series with L1 -> C1 -> L2 -> GND. The components parameter are as follow:

L1 - 586nH, Ql=100, F=13.56MHz, Rdc=0.5
C1 - 102.5pF, Qc = 100, F= 13.56MHz
L2 - 750nH, Ql=100, F=13.56MHz, Rdc=0.5

A Linear analysis looking into L1 resulted to 3.283-0.67j input impedance which is correct based on my own calculations.

However, a transient analysis resulted rather an incorrect result. With this small input impedance, I would expect the ac Voltage at the input(looking into L1) would be in the order of 0.56Vpeak. But, the simulation resulted to 6.2Vpeak. Also, the voltage node at C1 and L3 were all wrong too.

If L1, C1 and L2 are removed and replaced with R and say R=3ohm, transient analysis would give me the correct answer, which is about 0.56Vpeak. Linear analysis would resulted to of course 3+0j input impedance.

Any idea guys? Any suggestion/helps are appreciated.