The BASIC TRANSISTOR AMPLIFIER amplifies by producing a large change in collector
current for a small change in base current. This action results in voltage amplification because the load
resistor placed in series with the collector reacts to these large changes in collector current which, in turn,
results in large variations in the output voltage.
The three types of BIAS used to properly bias a transistor are base-current bias (fixed bias), self-bias,
and combination bias.
Combination bias is the one most widely used because it improves circuit stability and at the same
time overcomes some of the disadvantages of base-current bias and self-bias.
THE CLASS OF AMPLIFIER OPERATION is determined by the portion of the input signal for
which there is an output.