Common Base Amplifier

Question 1

This is a Common Base amplifier because the input is applied to the ____, the output is taken from the ____, and the ____ is common.

Answer 1

This is a Common Base amplifier because the input is applied to the emitter, the output is taken from the collector, and the base is common.

Question 2

What are the two basic circuits of the Common Base Amplifier?

What is common about the base?

Answer 2

Two basic circuits:

1. Input - Emitter to Base
2. Output - Base to Collector

The base is common to both circuits.

Question 3

Does change in one circuit affect the other? If so, how?

Answer 3

Yes

A changing input signal changes the bias voltage on the emitter of the transistor.

When the input signal increases, the emitter voltage increases, decreasing the forward bias on the base to emitter PN junction. A decreased forward bias decreases collector to emitter current.

When the input signal decreases, the voltage on the emitter decreases, increasing forward bias on the base to emitter PN junction. An increased forward bias increases emitter to collector current.

Question 4

An increasing input signal produces an ______ output signal.

A decreasing input signal produces a _______ output signal.

Answer 4

An increasing input signal produces an increasing output signal.

A decreasing input signal produces a decreasing output signal.