Bipolar Junction Transistors (BJTs)
A Bipolar Junction Transistor is a three terminals active semiconductor device formed by two back-to-back p-n junctions. The three terminals are labeled base, emitter and collector. Its main function is the current amplification between the collector or emitter currents and the base current.
There are 2 types of Bipolar Junction Transistor (BJT), the NPN and the PNP.
Circuit Analysis
To analyse a transistor circuit,
Analyse the BJT Common Emitter Amplifier
Configuration Characteristics |
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Common Emitter |
Common Collector |
Common Base |
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Input |
Base |
Base |
Emitter |
|
Output |
Collector |
Emitter |
Collector |
|
Input/Output Phase relationship |
180o |
0o |
0o |
|
Voltage Gain |
Medium |
Unity |
High |
|
Current Gain |
Medium |
High |
Unity |
|
Input Impedance |
Medium |
High |
Low |
|
Output Impedance |
Medium |
Low |
High |