Definition of power amplifier A transistor amplifier which raises the power level of the signals that have audio frequency range is known as transistor power amplifier. In general the last stage of multistage amplifier is the power stage. A power amplifier differs from the voltage amplifier. A transistor that is suitable for power amplification is generally called as power transistor. Classification of Power Amplifier The power amplifiers can be classified in the following ways. 1. According to the usage of Frequency Signals: (i) Audio frequency power amplifiers. (ii) Radio frequency power amplifiers. (iii) Video frequency power amplifiers. 2. A...