The CA3080 and CA3080A types are Gatable-Gain Blocks which utilize the unique operationaltransconductance-amplifier (OTA) concept. The CA3080 and CA3080A types have differential input and single-ended, push-pull, class A output. In addition, these types have an amplifier bias input which may be used either for gating or for linear gain control. These types also have a high output impedance and their transconductance (gM) is directly proportional to the amplifier bias current (IABC). The CA3080 and CA3080A types are notable for their excellent slew rate (50V/µs), which makes them especially useful for multiplexer and fast unity-gain voltage followers. These types are especially applicable for multiplexer applications because power is consumed only when the devices are in the “ON” channel state.
"An Operational Transconductance Amplifier ("OTA") is something like an opamp, but is really quite different. It's an amplifier; and like an opamp it has a pair of differential inputs and a single output. But the output is a current source instead of a voltage source. The gain of the amplifier is expressed as a transconductance (current out / voltage in), and that gain is programmable because it is proportional to the current going into a gain programming pin. While opamps are almost always implementing some function by the use of a specific feedback network, the OTA is very often used open loop (or partially open loop)." - Don Tillman