Re: gEDA-user: noise analysis in ngspice?

[John Doty <jpd@xxxxxxxxxxxxx>]

On Feb 21, 2006, at 12:52 PM, Ron Crummett wrote:

> Hi -
>
> We are learning noise analysis in my communications circuits class  
> right now.  My instructor does simulations with WinSpice, but I try  
> using ngspice to do them as well.  Up until now it's worked great,  
> but noise analysis does not.  When I try to run a netlist that  
> includes noise analysis parameters in WinSpice it works fine, but  
> in ngspice I get errors, telling me "Noise input source Vac not  
> found in circuit" and then aborts the noise simulation.  I have  
> attached my netlist here for observation; what do I need to  
> change?  Thanks.
>
> -Ron Crummett
> HW5_1.cir - EE 513, Assignment 5, Problem 1
>
> .control
> destroy all
> op
> noise v(2) Vac dec 20 10 10meg
             ^
ngspice normally converts names to lower case, but apparently forgets  
to do so here, so your circuit has a source vac but noise looks for  
Vac. A bug, but just use lower case and you'll have no trouble. I  
don't know if anyone's paying attention to ngspice bug reports these  
days. Fortunately, bugs are few (fewer than I encountered in PSpice  
some years ago).

> .endc
>
> *circuit
> Vac 1 0 ac 1
> R1 1 2 100k
> C1 2 0 1p
> .end

John Doty              Noqsi Aerospace, Ltd.
jpd@xxxxxxxxxxxxx