SpectreRF pss convergence

[bodhisatwa]

pss convergence

Hi,

I have designed an oscillator using a custom made inductor. The inductor was designed in ADS Momentum. I wanted to simulate the oscillator phase noise in Spectre. So I exported the S parameter matrix from Momentum (touchstone file), and used a 2-port black-box (analogLib) with data from this touchstone file. The 2-port black-box essentially emulates the custom made inductor.

I am able to run transient simulations and view the oscillations properly. However, I am NOT getting pss to converge.

I have read the older posts on pss convergence, and they haven't helped. The circuit converges easily for inductors in the design kit (I am using ibm bicmos 0.13um process), but fails consistently for the 2-port black-box. Will be great if I can get some pointers on this.

Thanks,
Bodhisatwa

 

[saro_k_82]

spectrerf pss

What is the Q of the inductor? If that is high., it will take that many cycles to converge(assuming this dominates the circuit Q). If that is feasible, have a long tstab for the pss run.

 

[bodhisatwa]

pss touchstone

The Q of the inductor is between 12 and 15. I have already used a high value of tstab, and that doesn't work.

My guess is the problem lies with trying to perform pss on S-parameter (frequency domain) data. I say that because a similar inductor (same inductance and Q) from the kit works. The black-box, representing the custom-made inductor), doesn't.