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Re: [Help-gnucap] Time step control

From: al davis
Subject: Re: [Help-gnucap] Time step control
Date: Mon, 3 Dec 2007 11:19:21 -0500
User-agent: KMail/1.9.7

On Monday 03 December 2007, a r wrote:
> 1. there is something wrong with the pulse formula:
> "pulse (0 2.5 2.5n 0.01n 0.01n 1.48n 3n)" does not generate
> 1.48n width pulses. I will look into it later.

It works for me.

> 2. (this seems more critical) time step is not decreased (or
> not decreased enough) when the transition occurs. Sure,
> additional events are added but all devices (bsim3) driven by
> this signal are not modeled exactly.

You requested "method=euler", which disables truncation error 
based step control.  Try "method=trap".

It might seem like we are going in a circle, with my 
recommending trap now.  Actually, with the pulse properly 
generating events now it should work.

Truncation error control should make the steps small enough to 
avoid trap ringing, provided you set the tolerances 
correctly.  "trtol=1".

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