Re: gEDA-user: geda-user Digest, Vol 34, Issue 18

[Yamazaki R2 <yamazakir2@xxxxxxxxx>]

> Message: 8
> Date: Fri, 6 Mar 2009 21:39:03 +0000
> From: r <nbs.public@xxxxxxxxx>
> Subject: Re: gEDA-user: Using .global statements in GNUcap and mult
>        transistors
> To: gEDA user mailing list <geda-user@xxxxxxxxxxxxxx>
> Message-ID:
>        <5b9d31e90903061339u25098f5ava9905d1d307b383c@xxxxxxxxxxxxxx>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On Thu, Mar 5, 2009 at 2:23 AM, al davis <ad151@xxxxxxxxxxxxxxxx> wrote:
>>
>>> >
>>> > The Gnucap behavior is consistent with Hspice and Spectre.
>>> > ?At least that is what I have been told. ?I don't have
>>> > access to them to check it out.
>>>
>>> That's incorrect. Both Spectre and Hspice treat devices with
>>> m>1 as single entities.
>>
>> ok .... ?maybe you can help solve this.
>
> Well, I'm not sure. I don't know how it is implemented in these
> simulators. I guess these guys have simply modified the models (they
> have modified quite a few other things there so I guess they wouldn't
> have minded adding "m" parameter as well).
>
>> Also consider that there are a bunch of parameters that can be
>> probed. ?Some multiply, some divide, some are not changed.
>> There is no indication in the code of which is which. ?There
>> could be hundreds of parameters that could be probed. ?All that
>> is known is a name and the type (real, int, string, ....) that
>> it returns. ?There is no notion of across, through, or anything
>> that helps the decision of how to scale.
>
> Perhaps it could be done at the time of stamping the matrix - by
> multiplying all gm's by a factor of "m". Then all the probes would
> "just work". I have no idea how it could be done technically, though.
>
> BTW, some simulators preprocess the netlist and reduce parallel
> devices into a single device with an "m" parameter set. This gives a
> huge performance boost in extracted sims.
>
> -r.

**WOW** I'm an idiot I can't believe I didn't think of that! I'll just
add a wrapper script for my simulations to preprocess the netlist and
merge the transistors with the m parameter. That should be a quick and
easy solution until gnucap automatically does this for you. If anybody
is interested I can post the script on the mailing list for everybody
else to use. I'll probably just use perl for regex capability.


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