chapter  14
22 Pages

Amplifiers: Cascading Stages

A very weak signal cannot be sufficiently amplified by a single stage amplier, like those we have dealt with so far-amplifiers made only of a single biased transistor forming a complete network. Single-stage transistor amplifiers can be inadequate for meeting most design requirements for any of the four amplifier types (voltage, current, transresistance, and transconductance). If a microphone produces about 20 mV under normal conditions, you will need a single stage of amplification, but if it produces only 1 mV, you will need two or more stages of amplification, that is, a multistage amplier, to provide greater amplification than a single stage could provide by itself.