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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.

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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.

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  • \$\begingroup\$ Any clue about what program you are using? If this is LTSpice, all you do is do a left-mouse-down on one node, hold the left button down and drag over to another node watching for the other probe symbol to appear, and then release. Or you can edit the display window's equation itself, if you know how to do that. \$\endgroup\$ – jonk Oct 19 '17 at 19:39
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Click on voltage point 1 - hold down your left mouse button - drag to voltage point 2 - release. You can also manually type in your expression for the waveform V(node1)-V(node2).

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