Re: [ng-spice] Readline Response


To ng-spice@ieee.ing.uniroma1.it
From Michele Quarantelli <quarante@legs.ing.unibs.it>
Date Wed, 25 Aug 1999 22:41:12 +0200
Delivered-To mailing list ng-spice@ieee.ing.uniroma1.it
In-Reply-To Your message of "Wed, 25 Aug 1999 19:47:04 +0200." <Pine.LNX.3.96.990825193506.5933A-100000@ieee.ing.uniroma1.it >
Mailing-List contact ng-spice-help@ieee.ing.uniroma1.it; run by ezmlm
Reply-To ng-spice@ieee.ing.uniroma1.it

> 
> 
> On Wed, 25 Aug 1999, Michele Quarantelli wrote:
> 
> > Traditional transient analysis is based on a direct integration
> > of circuit equations using some kind of BDF. This approach definitively 
>cov
> ers
> > most of the designer's need. However, when dealing with high frequency (> 
> > 100Meg) systems where signals with very different time scales exist the 
> > analysis has to be carried out with a very fine time-step to "catch" the 
> > fastest signal and long enough to cover the entire low frequency signal 
> > spectrum (e.g. a mixer working at 900meg downconverting a 200k signal).
> > The traditional approach in this case doesn't fit very well ...
> > Different algorithms have been developed to solve the time domain steady 
>st
> ate
> > condition of a circuit and I mentioned some of them up above ... I'm sure 
>y
> ou
> > have heard of commercial simulators like Spectre, Harmonica, etc ... 
>which 
> > implement some of the above algorithms.
> > It would be nice to have some of them included ...
> Yes, have heard of them but never used Spectre or Harmonica and do not
> know the algorithms you mention, someone else knows them ?
> 
> 
> > A final note: I'm currently comparing the last release of Berkeley Spice 
> > (spice3f5fix) against ng-spice. During op simulation of a LNA amplifier 
> > (including a grounded MOS device as a capacitor) I saw ng-spice 
>converging 
> to 
> > the wrong solution (i.e. vds not equal to zero) !!! I was using MOSIS 
>BSIM3
> v1 
> > model so I re-compiled the bsim3v1 code (with some modification ... of 
>cour
> se)
> > and ... same result !!! At this point I'm quite concerned with ng-spice 
> > reliability ... Anyone having the same problem ?
> ng-spice reliability is still to be tested. We changed the code in various
> parts, and probably exploited an hidden  bug (or inserted a new one). Can
> you send to the list the netlist and modelcards so that we can perform our
> simulations and try to discover the bug ?
> 
Unfortunately I cannot release the netlist so far, but I'll try with some
other circuit to see if I fall into the same pit.

> Anyway: did you compiled in the bsim3v1 code included in spice3f5fix or
> another one ? I had the same problem linkng all three B3SOI models in a
> single executable: the PD model did not converged for one test circuit,
> while the spice compiled with the PD model only converged. May be I have
> not understood something in device code.
> 
I used the bsim3 code from spice3f5fix plus I added the test for compatibility
with Cider implementation.

> 
> > Also how do I access the develpment release ? I tried anonymous cvs but 
>it 
> > didn't work .
> 
> the login is anonymous and password: guest
> you need to: export
> CVSROOT=:pserver:anonymous@ieee.ing.uniroma1.it:/var/services/cvsroot
> 
> then launch the command:
> 
> cvs login
> 
> if it does not works, try:
> 
> cvs -d :pserver:anonymous@ieee.ing.uniroma1.it:/var/services/cvsroot login
> 
> you will be requested for a password: guest,
> 
> and then you can do your job (there is no confirmation for the login
> procedure).
> 
> Paolo
> 
OK I will try again ... I'll let you know.

Michele

Partial thread listing: