www.uni-bonn.de/~uzs159/ota3080.html, From the page:
In the late sixties, RCA, then one of the major leaders in linear semiconductors, came out with the Operational Transconductance Amplifier, hereafter called OTA. The name means essentially a controllable resistance amplifier. The control input is a current. Like an operational amplifier, there are differential inputs. These inputs are used to modulate the control current. Unlike an op amp, the output of the OTA is a current! Unlike an op amp, there is not a single resistor in the OTA circuit.
I first learned of the OTA in the late sixties from my then employer, Dr. Robert A. Moog, whom a few of you may have heard of. Bob was quite enamoured of the CA3080, but I canít recall any Moog product during my tenure that ever used it. (Note, I worked for Moog during the modular synth days, before MiniMoog).