Spectre netlist defining voltage gain and saving the results to view in the psf file

If you want small-signal gain, you could use an xf analysis:

xf (Vout 0) xf start=1 stop=1G

Then in the xf results, you'll see listed all the voltage sources in the circuit. Assuming there's one which is connected to the Vin signal, you can set the results browser to plot in dB20 (it will show Default and Magnitude at the top of the results browser; change the Magnitude to dB20). Double click on the voltage source and you'll get the gain in dB.

Andrew

Is this also the way to do it for differential nodes?

The output of an xf analysis can certainly be differential. If the input is a single voltage source (across a differential input, biased somehow) then you could use xf analysis. Or you could use ac analysis and have two input sources each with (say) mag=0.5 (phase set appropriate or one source inverted) and then plot the output voltage in the ac results between the two output nodes.

Andrew

Thanks so much for the quick answers. I was able to get the transfer gain using both methods. I was wondering if there's a way to save differential voltage without using calc in ViVA. The method I am using now is something like:

VpOUT (OUT 0) bsource v=v(OUTP, OUTN)

Then node OUT is saved as differential voltage.

I might be missing a simple way to do the same.

Or simpler still:

VpOUT (OUT 0 OUTP OUTN) vcvs gain=1

Note that ViVA can also plot differential signals without needing to use the calculator.

Andrew