Introduction to Amplifiers
An amplifier is a circuit which increases the strength of a
weak signal. The amplifier of the input signal is generally very small of some
micro volts to several volts. Amplifiers that are dealing with input voltage of
very small magnitudes will operate only in the linear portion of the transistor
characteristics. Such a type of amplifiers are called signal amplifiers. Small
signal amplifiers may operate in the range of audio frequencies, radio
frequencies, video frequencies or at ultra-high frequencies.