Explain the operation of a unijunction transistor (UJT) and its applications.
1 Answer
A Unijunction Transistor (UJT) is a three-terminal semiconductor device that operates as a voltage-controlled oscillator, relaxation oscillator, or pulse generator. It is a type of transistor that works based on the principles of a pn-junction diode and exhibits a unique behavior that makes it useful in specific applications.
Operation:
A UJT is typically made from a single type of semiconductor material (e.g., N-type silicon) and has three terminals: an emitter (E), a base1 (B1), and a base2 (B2). The emitter terminal is connected to one end of the semiconductor material, while the base1 and base2 terminals are connected to the other end.
The operation of a UJT can be summarized as follows:
Biasing: When a positive voltage (typically a few tenths of a volt) is applied to the emitter terminal with respect to the base1 terminal, a small current starts flowing from the emitter to the base1 region. This current is called the "emitter current" (IE). However, this initial biasing is not enough to make the UJT conduct significantly.
Intrinsic Standoff Ratio (η): The UJT has an intrinsic standoff ratio (η), which is a ratio of the resistance between the emitter and base1 terminals to the resistance between the emitter and base2 terminals. This ratio is usually around 0.6 to 0.
Operation:
A UJT is typically made from a single type of semiconductor material (e.g., N-type silicon) and has three terminals: an emitter (E), a base1 (B1), and a base2 (B2). The emitter terminal is connected to one end of the semiconductor material, while the base1 and base2 terminals are connected to the other end.
The operation of a UJT can be summarized as follows:
Biasing: When a positive voltage (typically a few tenths of a volt) is applied to the emitter terminal with respect to the base1 terminal, a small current starts flowing from the emitter to the base1 region. This current is called the "emitter current" (IE). However, this initial biasing is not enough to make the UJT conduct significantly.
Intrinsic Standoff Ratio (η): The UJT has an intrinsic standoff ratio (η), which is a ratio of the resistance between the emitter and base1 terminals to the resistance between the emitter and base2 terminals. This ratio is usually around 0.6 to 0.