A three-terminal nonlinear device composed of two bipolar junctions (collector-base, baseemitter) in close proximity. In normal operation, the voltage between base and emitter terminals is used to control the emitter current. The collector current either equals this (with BC junction in reverse bias), or goes into saturation (the BC junction goes into forward bias). Used for medium power (700 A) and medium speed (10 kHz) applications. In power electronics applications, BJTs are typically operated as switches, in either
their fully on or off states, to minimize losses. The base current flowing into the middle of the device controls the on–off state, where continuous base current is required to be in the on state. A disadvantage is the low current gain.
The base current is generally much smaller than collector and emitter currents,
but not negligible as in MOSFETs.
their fully on or off states, to minimize losses. The base current flowing into the middle of the device controls the on–off state, where continuous base current is required to be in the on state. A disadvantage is the low current gain.
The base current is generally much smaller than collector and emitter currents,
but not negligible as in MOSFETs.
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