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Simulators >> RF Simulators >> PSS Accuracy Defaults Setting
https://designers-guide.org/forum/YaBB.pl?num=1062590322

Message started by Ray Lin on Sep 3^rd, 2003, 4:58am

Title: PSS Accuracy Defaults Setting
Post by Ray Lin on Sep 3^rd, 2003, 4:58am

Hi, I want to simulate phase noise and oscillating frequency of a VCO by pss and pnoise simulation.
My friend told to me that "Do not choose any option in pss accuracy defaults setting, even conservative. " He said this information came from a Cadence FAE. The FAE said thet Do not choose any option will give you the most accuracy result. But the user's guide showed me that the default is moderate. So I'm confused about this setting in pss simulation. Does Do not choose any option gives more accurate result than that of conservative one??

Regards, Ray :o

Title: Re: PSS Accuracy Defaults Setting
Post by gatsby on Sep 3^rd, 2003, 11:58am

what I've heard from cadence is 'do not use conservative or liberal' and
'moderate has no effect' . This is applicable to IC4.4.6 (for IC5.0 you can
go ahead and use conservative/ liberal or whatever as they are properly
implemented). So, leave all accuracy default buttons unchecked and play with
accuracy settings reltol, abstol etc

Title: Re: PSS Accuracy Defaults Setting
Post by Ray_Lin on Sep 3^rd, 2003, 8:05pm

Thanks a lot :D

Title: Re: PSS Accuracy Defaults Setting
Post by Andrew Beckett on Sep 3^rd, 2003, 10:39pm

All three errpresets have been revamped in IC50, to
optimise them using tests on lots of circuits, and also
to take into account the new Multi-Interval Chebychev
option (the "highorder" option) for improving the
numerical noise floor that came in for PSS in IC50.

Prior to IC50, the errpreset settings were not particularly
good and so it was usually best to set some of the
individual settings:

reltol: 1e-4 or 1e-5
relref: alllocal
method: gear2only
steadyratio: 0.001 (I think that's the default).

you might also want to tighten vabstol/iabstol a little.

However, your mileage may vary, and so you should
_think_ about the settings rather than just wildly
guessing! See Ken's book for more advice on
the effect of the transient/DC tolerance options.

In IC50 we'd generally recommend you set the errpresets,
and only override them if you need to (and know what
you're doing).

Regards,

Andrew.