Xref: utzoo sci.research:1531 sci.electronics:17983
Newsgroups: sci.research,sci.electronics
Path: utzoo!utgpu!watserv1!vlsi!jabarby
From: jabarby@vlsi.waterloo.edu (J.A. Barby)
Subject: Re: Variable Capacitor in SPICE
Message-ID: <1991Feb23.020014.25388@vlsi.waterloo.edu>
Organization: University of Waterloo
References: <1991Feb21.223126.15937@sol.UVic.CA>
Date: Sat, 23 Feb 1991 02:00:14 GMT
Lines: 32

In article <1991Feb21.223126.15937@sol.UVic.CA>, shankar@face.UVic.CA (P.S.Shankar.) writes:
> 
>    I am trying to simulate what is essentially a RC circuit using SPICE.
>    I am using Spice 3.0 C, although I can use IG-SPICE if i need to.  I
>    need to put in a few capacitors, whose values depend on the voltages on
>    them, all of which are typically time-varying. More precisely, i need
>    to simulate capacitors which vary as
> 
>                                   k1
>                    C =        ------------
>                                k2 - k3.C.V
> 
>    where k1, k2 and k3 are constants and the C and V are the capacitor and 
>    the voltage values associated with the capacitor itself.  Alternatively,
>    this can be written as 
>                                        
>                              c1    c2   __________
>                        C =  --- + ---- \/(c3 - V )
>                              V     V
> 
>     I have tried to go through the available built-in utilities and functions
>     but cant seem to find one, close enough to help me on this one! 
>     If any of you spice wizards out there have a clue regarding this, 
>     please email me ( or post it on the net...).  

I would suggest that you switch to using SABER from Analogy (Beaverton,
Oregon).  Saber makes these sort of thing easy.  An educational license
is only around 1,500.
-- 
	Jim Barby  (U of Waterloo VLSI Group, Waterloo Ont.)
	jabarby@vlsi.waterloo.{cdn,edu,bitnet}
	jabarby@vlsi.UWaterloo.ca


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