How could you measure the voltage difference between two nodes on a circuit? For example, for the following differential pair I wanted to check if the differential-mode gain is -120. I used a big resistor, R_sense, and put it across the individual outputs like below.
Then I measured the current through it and the rest you know. It worked very well and let me find the differential gain. But I would like to know if there exists a built-in solution for that? For example, I want to be able to click on two arbitrary nodes and immediately see the voltage difference on the plot window. I searched but didn't find anything.