From: Jim Thompson
Subject: Re: Taking into account device variations with Spice?
References: <3E15F448.6DB56D48@worldonline.fr> <3E160503.76CDF5D8@worldonline.fr>
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Date: Fri, 03 Jan 2003 21:52:47 GMT
NNTP-Posting-Date: Fri, 03 Jan 2003 16:52:47 EST
Organization: Cox Communications
On Fri, 03 Jan 2003 22:47:48 +0100,
In Newsgroup: sci.electronics.design,
Entitled: "Re: Taking into account device variations with Spice?",
Wrote the following:
|Jim Thompson wrote:
|> On Fri, 03 Jan 2003 21:36:24 +0100,
|> "A.Iakovlev" ,
|> In Newsgroup: sci.electronics.design,
|> Article: <3E15F448.6DB56D48@worldonline.fr>,
|> Entitled: "Taking into account device variations with Spice?",
|> Wrote the following:
|> |Hello Spice gurus,
|> |I would like to learn how to evaluate the limits of a circuit's
|> |characteristics due to the variation of the parameters of the real world
|> |parts, with Spice. I mean the technological variation of a given part
|> |type, in the limits specified in the datasheet. I guess that I need to
|> |go through the simplest cases first, but my current practical interest
|> |is evaluating the maximum THD of a three-bjt circuit, on the space of
|> |the technological and temperature variations of all the parts (some
|> |resistances, one zener, three bjts). Thanks a lot for any pointers /
|> Use Monte Carlo or worst-case.
|Is it possible to make it work on THD value (.four analysis) ?
|Then, it looks like one has to specify the variation of all the parameters
|one by one (DEV/LOT for each parameter); I have not yet seen this in the
|manufacturers - provided models... What would be a practical approach for
|bjts (the most important parameters?)?
The most important parameters (for THD purposes) are likely to be BF
The range I'd use for BF would be BFspec/2 and 2*BFspec
For VAF use VAFspec/2 and infinity (delete VAF from the model card or
use a very large number, like 1000V).
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
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