Signal Amplifiers

Amplification is needed whenever a signal (coming from a transducer, an antenna, etc.) is too small to be efficiently processed. A signal amplifier is primarily intended to operate on very small input signals with the aim of increasing the signal energy. For instance, a voltage amplifier works with input signals in the range of millivolts or even microvolts and has to provide a power gain. This last property distinguishes a voltage amplifier from a transformer. A transformer, in fact, can provide an output voltage greater than the input (primary) voltage, but the output power never exceeds the power supplied by the signal source. The smallest signal which can be detected and amplified is limited by the noise performance of the amplifier. In fact, noise masks the signal so that recovery may not be possible. Linearity is another fundamental requirement for a signal amplifier, in order to ensure that the signal information is not changed and no new information is introduced.