Question

Can a transistor be used as a rectifier?

Answer 1

Yes, a transistor can be used as a rectifier.

1. A rectifier is a device that is utilized for converting alternating current to direct current. On the contrary, a Transistor finds its application either as an amplifier or a switch.
2. For an AC current, rectification can be done by using a single transistor. A simple circuit composed of a transistor, a biasing diode, and a few resistors can enable us to rectify AC with a voltage of $0.3V$or less.
3. The rectification can be done either for a positive half-cycle or a negative half-cycle depending on the type of the transistor whether PNP or NPN is used respectively.
4. The AC, which needs rectification, is introduced into the emitter circuit.
5. In the case of an NPN transistor, when a low negative voltage is being applied at the emitter, then an emitter current flows towards the collector. For the positive phase, it becomes reverse biased, however, the base-collector junction is forward biased, which is unable to generate current as the voltage drop across the biased diode is insufficient. Hence, the circuit can behave as a one-way rectifier.

Hence, a transistor can be used as a rectifier.