Recommended · for some experience
#193: Back to Basics: the differential amplifier, aka long-tailed pair, diff-pair
Why people recommend it
Alan Wolke gives a gentle introduction to the BJT differential pair and how it forms an op amp input stage; people build and simulate along with it.
In their words
This youtube video by Alan Wolke (W2AEW) is a nice gentle introduction to the differential pair amplifier, and he points to how it might be used for an op amp input stage.
scanny on electronics.stackexchange.com, Oct 2015. CC BY-SA.
According to the example shown here: [video], with changing the Vbe drop across Q1, the I_e1 should change inversely proportional to I_e2.
lucenzo97 on electronics.stackexchange.com, Oct 2017. CC BY-SA.
