Re: gEDA-user: gnucap tranient response (noisy nodes)

[al davis <ad151@xxxxxxxxxxxxxxxx>]

On Wednesday 04 March 2009, Yamazaki R2 wrote:
> Has anybody ran into this issue doing tranient reponses with
> gnucap? It seems like bias point calculations work fine, but
> when I do a transient reponse even at steady state conditions
> (all voltages DC), when I look at bias voltages (for example
> the gate of a diode connected mosfet) it seems like the
> solver is very noisy to those nodes, as in the bias voltages
> seems the go up and down 3-4mV at random as if there was some
> noise on the circuit. When I simulate the circuit with
> ngspice with the exact same netlist and models, the circuit's
> transient reponse is a lot more stable.

Actually I have seen just the opposite.  I would like to see 
your circuit.

What version of gnucap?
How are the options (including tolerances) set?
Is the jitter within the tolerance you specified?
You might try ".option nobypass noincmode notraceload" and see 
if that helps.


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