Re: gEDA-user: GSchem in CMOS Analog IC context?

[John Doty <jpd@xxxxxxxxx>]

On Mar 8, 2009, at 7:22 AM, Stuart Brorson wrote:

> Hi --
>
>> Has anyone successfully used GSchem in an CMOS analog IC context? --
>> I'm looking at a plain-vanilla +MIM TSMC CMOS process at the ~ 0.18
>> to 0.35u node. Has anyone built symbols for the typical TSMC nodes
>> (parameterized NMOS,CMOS,resistors with appropriate sheet resistance
>> and tempco)?


Dale, assuming you're using SPICE, the question is whether the  
currently maintained gnetlist back end (spice-sdb) understands the  
parameter names. A regular resistor symbol should work fine with the  
right attributes.

So, Stuart, does spice-sdb know how to transfer attributes to  
parameters in the following syntax (ngspice)?

General form:

        RXXXXXXX n+ n- <value> <mname> <l=length> <w=width> <temp=val>
        +        <dtemp=val> m=<val> <ac=val> <scale=val> <noisy = 0|1>


>
> Peter Kaiser in Germany has done some chip designs using gEDA.  Here's
> the website he put up recording some of his tips, including some
> symbols for instantiating devices:
>
> http://www.easyasic.com/
>
> You might try contacting him in person if you have questions.  His
> e-mail addr is on his website.
>
> John Doty has also done mixed-signal designs using gEDA.  He has
> published papers on his work, and has written an interesting gnetlist
> back-end, all of which he has posted on his website.  I didn't see any
> schematic symbols on his website, but here's a link:
>
> http://www.noqsi.com/home.html
>
> John is very active on the e-mail list, so I expect that he'll turn up
> to provide more info to you soon.

Gotta be less predictable ;-)

Dale, I've done several design variations on my delta-sigma CCD  
chains using 350 nm TSMC. However, I haven't gotten into careful  
modeling of the resistors. I use very few resistors in these designs,  
always in noncritical places. Gains are set by capacitor ratios.

If you're interested, I've been working on symbols for professor  
Ikeda's OpenIP (http://research.kek.jp/people/ikeda/openIP/). I can  
send you an alpha version of that library if you wish (you get to  
check them, as I've only used a subset), and I can answer specific  
questions if you can't read the Japanese documentation.

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




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