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Message started by blue111 on Aug 9th, 2017, 8:27pm

Title: Active Inductor simulation
Post by blue111 on Aug 9th, 2017, 8:27pm

I am using ngspice to simulate active inductor in https://github.com/promach/frequency_trap

why Vtest = -2 ?


Title: Re: Active Inductor simulation
Post by Geoffrey_Coram on Aug 11th, 2017, 7:53am

Perhaps because of the "ac 2" in the source description for the source Vtest? I can't tell the polarity of the source in the schematic.

Title: Re: Active Inductor simulation
Post by Ken Kundert on Aug 11th, 2017, 11:53am

It is very strange that AC results would be negative. By the default the magnitude should be shown. Did you ask for the real part to be plotted?

-Ken

Title: Re: Active Inductor simulation
Post by mhx on Aug 11th, 2017, 10:02pm

> why Vtest = -2 ?

(I wonder: Cs=100uF, Cl=1F?)

In case you are doing this with NGSPICE:
the NGSPICE plot command "plot V(test)"
displays -2. (The real part of V(test)).
This is because the positive terminal of
the AC source is grounded.
Try plot abs(V(test)) instead.

-marcel

Title: Re: Active Inductor simulation
Post by blue111 on Sep 7th, 2017, 9:23pm

@mhx

is there a way to put 'plot v_ip_out#branch' inside spice-epilog control directive without any syntax error ?

Note: this only works in ngspice interactive terminal, but not in gschem spice-epilog control directive.


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