RE: initial_step and final_step in DC sweep

Hi Geoffrey,

    So is it safe for the simulator to modify the variables that are
dependent on the swept parameter, even if they are assigned in the
initial_step?

Ilya


-----Original Message-----
From: owner-verilog-ams@eda.org [mailto:owner-verilog-ams@eda.org] On
Behalf Of Geoffrey.Coram
Sent: Friday, August 25, 2006 9:22 AM
Cc: verilog-ams
Subject: Re: initial_step and final_step in DC sweep

Marq -

Ack!  Those Silvaco models ... they were a true mess when I first saw
them (they had capacitance models implememented with a $sit_get_prev(),
where sit = silvaco internal task, so they weren't charge-conserving).
I didn't actually code the model myself; I gave Silvaco some feedback
and they put my name in the header as though I was the author.

If you look at my MOS11 model, also on the Designer's Guide site, you'll
see that I do not use initial_step.

I'll admit, I was forced to use initial_step for one RF simulator, where
we were only interested in transient performance, and it was not smart
enough at the time to build the dependency tree.

-Geoffrey


Marq Kole wrote:
> 
> Geoffrey,
> 
> :-))  <---- really big grin
> 
> In my most recent case it is a BSIM4 model that you coded, available
from Silvaco, linked through by the Designer's Guide. Admittedly, it is
from March 2004 (says the header - it's version 4.3.0 so it can't be
older than 2003 when that model was released in C code). I've been
updating it to version 4.4.0.
> 
> Rest assured that you're far from the only one; among the many others 
> I've always been doing it myself. I'll to change my ways ... :-)
> 
> I'm more concerned about implementers having this implemented without
considering the nitty-gritty detail of the standard.
> 
> Marq