The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Simulators >> RF Simulators >> how the number of harmonics in PSS affects PAC simulation?
https://designers-guide.org/forum/YaBB.pl?num=1295580615

Message started by sapphire on Jan 20^th, 2011, 7:30pm

Title: how the number of harmonics in PSS affects PAC simulation?
Post by sapphire on Jan 20^th, 2011, 7:30pm

Hi,

I want to simulate the supply rejection of my regulator using PAC. The regulator is used to provide a clean "supply" for ring osillators in a PLL. This is only a standalone simulation containing only regulator, oscillators, and some bias circuits.

Since I am only interested in the harmonic index=0 output frequency response, can I set the number of harmonics in PSS simulation to 0? This saves me a lot of time and it's much easier to get convergion. I think noise folding is not the case here, so higher harmonics wont contribute to the PAC accuracy. Please correct me if I am wrong.

Regards,
Sapphire

Title: Re: how the number of harmonics in PSS affects PAC simulation?
Post by Andrew Beckett on Jan 21^st, 2011, 11:16pm

If using shooting, then the answer is yes, you should (in general) be able to set the number of harmonics in the PSS to 0. This is because there will be timepoints following the waveforms regardless of the number of harmonics requested, and the minimum number of timepoints produced is based on ensuring spectral accuracy up to 4 times max(maxHarmonicRequested,10).

If using harmonic balance, you'll need to ensure you've requested enough harmonics in the PSS to ensure that it can accurately represent the PSS solution in a frequency domain representation of the solution. So 0 would definitely not be OK then!

Regards,

Andrew