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

[John Doty <jpd@xxxxxxxxx>]

On Mar 6, 2009, at 8:38 PM, John Doty wrote:

>
> 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.

Oops, I think what you want isn't exactly what this does. It creates  
a single transistor from a multiple.

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




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