Editing Bipolar junction transistor (section)

==== Common-emitter current gain ====
The ''[[common-emitter]] current gain'' is represented by {{mvar|β}}<sub>F</sub> or the [[Two-port network#h-parameters|{{mvar|h}}-parameter]] {{mvar|h}}<sub>FE</sub>; it is approximately the ratio of the collector's direct current to the base's direct current in forward-active region. (The F subscript is used to indicate the forward-active mode of operation.) It is typically greater than 50 for small-signal transistors, but can be smaller in transistors designed for high-power applications. Both injection efficiency and recombination in the base reduce the BJT gain.