Transistor Amplifier Circuits Unit 2 – Common Base Circuit
UNIT 2 – COMMON BASE CIRCUIT
UNIT OBJECTIVE
At the completion of this unit, you will be able to demonstrate the operation of the common base
transistor amplifier circuit by using calculated and measured circuit conditions.
UNIT FUNDAMENTALS
The base terminal is common to the input and output signals in the common base (CB) transistor
circuit. The ac output signal of a common base (CB) circuit is in phase with the input signal.
For a PNP or NPN transistor to function normally in any type of amplifier circuit, the base-
emitter junction is forward biased, and the base-collector junction is reversed biased.
The emitter current (IE) increases very rapidly after the transistor is forward biased [base-emitter
voltage (VBE) of about 0.6 Vdc].