Transconductance

Definition

The gain of a transconductance amplifier (an amp in which a change in input voltage causes a linear change in output current). The basic gain of vacuum tubes and FETs is expressed as transconductance. It is represented with the symbol g_m.

The term derives from "transfer conductance" and is measured in siemens (S), where 1 siemens = 1 ampere per volt. It was formerly measured as "mho" (ohm spelled backwards).