AdvancedA-002-003-001
What is the alpha of a bipolar transistor?
A
Answer
Circuit design and power supplies
Type
A
The change of collector current with respect to emitter current
B
The change of base current with respect to collector current
C
The change of collector current with respect to gate current
D
The change of collector current with respect to base current
Answer Notes
In a bipolar junction transistor (BJT), the term 'alpha' (α) refers to the common-base current gain.
It is specifically defined as the change in collector current with respect to the change in emitter current. Because the emitter current is the sum of the base current and the collector current, the collector current is always slightly less than the emitter current.
As a result, the alpha value of a typical BJT is just slightly less than 1, usually between 0.95 and 0.99. Distractors mentioning 'gate current' are incorrect because gates belong to Field Effect Transistors (FETs), not BJTs.
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What is the beta of a bipolar transistor?