Minggu, 12 Maret 2017
A practical amplifier always consists of a num-ber of stages that amplify a weak signal until sufficient power is available to operate a loud-speaker or other output device. The first few stages in this multistage amplifier have the function of only volt-age amplification. However, the last stage is designed to provide maximum power. This final stage is known as power stage.
The term audio means the range of frequencies which our ears can hear. The range of human hearing extends from 20 Hz to 20 kHz. Therefore, audio am-plifiers amplify electrical signals that have a frequency range corresponding to the range of human hearing i.e. 20 Hz to 20 kHz. Fig. 12.1 shows the block diagram of an audio amplifier. The early stages build up the volt-age level of the signal while the last stage builds up power to a level sufficient to operate the loudspeaker. In this chapter, we shall talk about the final stage in a multistage amplifier—the power amplifier.