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Re: [Help-gnucap] Voltage Controlled Resistor Problem

From: al davis
Subject: Re: [Help-gnucap] Voltage Controlled Resistor Problem
Date: Mon, 9 Mar 2009 13:37:10 -0400
User-agent: KMail/1.9.9

On Wednesday 04 March 2009, Aurelio Cano wrote:
> Well, I want to build a current controlled resistor using the
> voltage controlled resistor circuit.
> First I establish a linear relationship between the input
> voltage and the resistor through a table (1V->1k,
> 2V->2k,...).
> Then, I put a current source (1mA) in the output nodes to
> measure the voltage in it.
>  >.model vvsr table 0,0k,1,1k order=1
>  >G1 a 0 VCR b 0 vvsr
>  >.VCR Ve a 0 b 0 vvsr
>  >Vi b 0 1
>  >Io 0 a 1m

> As you can see in the results of the simulation, the voltages
> in the output nodes are only half of I expected, for example,
> for Vi=5 I expected Va=5V (R=5k) and I obtain Va=2.5.
> What am I doing wrong?

You have two VCR's ...  G1 and Ve .. in parallel.

You specified the first (G1) in Hspice syntax, then the second 
(Ve) in ACS syntax.

I see how you made the mistake ..  The manual shows examples of 
two different ways of doing it, and it looked like you need the 

Some other comments ...

You don't need a table to establish a linear relationship.  If 
you just specify a value, you get a linear relationship.  A 
value of 1K will do what you want.

Thanks for asking.  You pointed out a place where the manual 
needs improvement.  It's good timing, because I am working on 
the manual for the next release, which is online at   .

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