Re: gEDA-user: Using .global statements in GNUcap and mult

[John Doty <jpd@xxxxxxxxx>]

On Mar 6, 2009, at 7:17 PM, Yamazaki R2 wrote:

> On Fri, Mar 6, 2009 at 6:09 PM, Yamazaki R2 <yamazakir2@xxxxxxxxx>  
> wrote:
>>> 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.

Note that John Sheahan's spicepp.pl does this, among other things. I  
don't know where you can find the "official" source of this anymore,  
but Google finds several, and I can send you one if you want.

>
>
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John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




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