Usage of transistor:

The bipolar junction transistor that is abbreviated as BJT was the most generally used transistor in the 1960s and 70s. Even later than MOSFETs became extensively available, the BJT remained the transistor of choice for several analog circuits like simple amplifiers due to their greater linearity and ease of manufacture. Desirable properties of MOSFETs, like their usefulness in low-power devices, generally in the CMOS configuration, permitted them to capture nearly all market share for digital circuits; more lately MOSFETs have captured most analog and power applications also, including modern power transmitters, clocked analog circuits, amplifiers, voltage regulators, motor drivers, etc.