Hello, I am trying to plot the transconductance of an OTA versus the DC differential voltage, varying from -0.9 to 0.9 Volts. In LTSpice, it is quite easy, due to the .step directive. I'm performing the AC simulation for each DC voltage appliet at the input of the differential pair, as it can be seen in the attached figures. However, in XSCHEM/NGSpice I did not get success. I think I need to construct two vectors, one for the voltages and other for the AC magnitude (phase is irrelevant for my study). And thereafter plot magnitude versus voltage. Can anyone show me how to deal with the vectors in order to make this plot? PS: in the plot, the current is shown, but since the AC differential voltage is 1.0 V, the numerical value is equal to the transconductance.