Differential Amplifier Design (Amplifiers #6)

Let's design a differential amplifier with an op-amp that rejects the common mode. This prepares us for the next video where we will make an instrumentation amplifier.
Aaron Danner is a professor in the Department of Electrical and Computer Engineering at the National University of Singapore.
danner.group
Video filmed and edited by Cheryl Lim.
@randomcheryl

[@drakejoseph513]

Thank you for making these! I've had some trouble understanding differential amplifiers for a while, but this clears things up! Keep up the good work.

[@comeflywithme1694]

Very helpful for review before my exam. Thank you.

[@oakspines7171]

Meaningful details analysis and systematic approach. Thanks.

[@paulperano9236]

Or leave the gain = 1 and and another stage immediately after to provide the gain required. This way you get a nice clean signal and at the gain you need.

[@jimh6189]

You beat me to it! He does show a better approach in the next video, but I think it would be interesting to compare your approach with the instrumentation amplifier.

[@sefalibhakat143]

Thanks..

[@huntma3787]

8:20 why is the more negative side of the differential voltage connected to the same gnd resistor R4? It doesn't have to be in real applications does it, you are just doing for ease of calculation

[@huntma3787]

Actually answered my own question, one can easily derive the same result using Vd = Vsig-pos - Vsig-neg and not assuming Vsig-neg is zero

[@SebastianRoubertMartinez]

i don't understand the original schematic based on KVL. based on the original schematic, v_1 = v_cm and v_2 = v_cm. and since v_cm is w.r.t. ground, there's a closed loop. so v_cm - v_cm + v_transducer = 0. this intutively doens't make sense