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Simulators >> RF Simulators >> Spice 'transient'&spectreRF'Pss'
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Message started by fchirouf on Nov 8^th, 2005, 2:07pm

Title: Spice 'transient'&spectreRF'Pss'
Post by fchirouf on Nov 8^th, 2005, 2:07pm

Hil all;
If we campare the traditionnal Spice (.trans) and Pss (based shooting technique). Who is the factor of speed analysis. (Tspice_# trans_analysis ) = ? (TspectrreRF_#pss_analysis).
Dose spectreRF is more sepeedely (5x)to more Spice simulator.
Advance thiks
-CF
;)

Title: Re: Spice 'transient'&spectreRF'Pss'
Post by Andrew Beckett on Nov 15^th, 2005, 11:47am

Please try to ask a clear question if you expect an answer. I understand that English may not be your first language (at least I hope it isn't, given how you've written), but it's not obvious what you're asking. I suspect you're trying to ask for the relative speeds of transient and PSS - but to be honest that's an impossible question to answer because it entirely depends on what you're doing. If you use PSS with some of the small signal analyses, simulating with transient is just impossible, so you're comparing chalk and cheese.

Regards,

Andrew.

Title: Re: Spice 'transient'&spectreRF'Pss'
Post by sheldon on Nov 18^th, 2005, 8:00pm

fchirouf,

While both PSS and transient analysis are time-domain
analyses, comparing their run time is like comparing the
run time of ac analysis to transient analysis. In absolute
terms one may be faster, but that has no meaning since you
still need to use both analysis to design circuits.

Transient analysis and periodic steady-state analysis solve
different problems so it does not make sense to directly compare
performance. It would be better to think of them as complementary
solutions for circuit design. An analogy might be that engineers
use both LaPlace transforms[transient analysis] and Fourier
transforms[PSS] when designing. Both are useful tools.

If the question is when to use which analyses, then to expand
on Andrew's comments:

1) PSS is only useful when the circuit has a periodic steady state,
for example, if you want to characterize the distortion in an
amplifier for a sinusoidal input.

2) In addition, PSS enables small-signal analysis of periodic
circuits, for example, you can measure the input impedance of
a switching regulator to verify that it won't oscillate when the
EMI filter is attached.

3) In most other cases you would use transient analysis, for example,
when simulated delay time, rise/fall time, slew rate.

4) Transient is also used for circuit verification, that is, the sign-off
simulation.

Best Regards,

Sheldon