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Re: [Help-gnucap] accessing portions of terminal currents

From: mcmahill
Subject: Re: [Help-gnucap] accessing portions of terminal currents
Date: Wed, 30 Jan 2002 11:15:10 -0500 (EST)

On Wed, 30 Jan 2002, Al Davis wrote:

> On Wednesday 30 January 2002 05:57 am, address@hidden wrote:
> > This may sound like a strange question.  Is there anyway with
> > junction devices such as diodes and bipolar transistors (when they
> > become available) to access only the portion of the terminal
> > current associated with the static junction characteristics and not
> > the part associated with charging the capacitances?  For example on
> > the diode I want to break out the charging currents to get at whats
> > left.  I can do this with controlled sources and using a couple of
> > diodes, 1 with the full model and the other with dynamic parameters
> > set to zero, but I was wondering if I can directly do it?
> If I interpret the question correctly ...
> .print tran IJ(D*) IC(D*)
> IJ is junction current, without the capacitor part.
> IC is the current through the capacitor part, without the DC part.
> "CAPCUR" is an alias for "IC".
> You can also probe the internal elements (Yj and Cj) directly, and 
> have access to any probes that they provide.
> .print tran I(Yj.D2) I(Cj.D2)
> Does this help?

In a big way.  This is most cool!  Thanks.  The application is for large
signal devices which contribute shot noise.  The noise isn't due to the
total terminal current though at high frequencies since a good bit is just
charging capacitances.

I will be poking fun at cadence over dinner tonight :)


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