Transconductance amplifiers, part 1: current sources | Op-Amp Basics, ep 14

Please join me in supporting Heifer International: https://fundraise.heifer.org/fundrais... If Heifer's web site is blocked in your area, try https://www.heifer.nl/en/homepage-en/ Schematics available on the project GitHub: https://github.com/kennykb/kevins-cav... CircuitJS models for the demo circuits: Op-amp current source with a floating load: https://tinyurl.com/s72mu4ts Add a pass transistor for a load returned to ground: https://tinyurl.com/4797e2bb Source and load both ground-referenced: https://tinyurl.com/yc39m9rm In this episode, we begin examining transconductanse amplifiers, whose input signals are expressed as voltages and whose output signals are expressed as currents. We build first a current source with a floating load, then show how the load can be returned to ground, and finally show how both source and load can be ground-referenced. There are numerous side paths for testing and debugging of the amplifiers. TIMELINE 00:00 Intro 00:58 Inverting transconductance amp 02:20 Noninverting transconductance amp 04:22 PSA 05:40 First build 08:41 First test 12:44 Ground-returned load 13:55 Second test and debug 16:44 What went wrong? 19:11 Using a pass MOSFET 20:01 Gate capacitance! 20:51 Ground-referenced input 22:36 Testing ground-referenced amp 23:18 Next steps CREDITS Image: "Fire" OpenClipArt user'dominiquechappard https://openclipart.org/169759 Public domain Music: “Light Sting” Kevin MacLeod (incompetech.com) Licensed under Creative Commons: By Attribution 4.0 License http://creativecommons.org/licenses/b... © 2026 Kevin B. Kenny