Patent ID: 7123730

Claim:
An audio power amplifying apparatus including first through B-th power amplifying terminals, each of which power-amplifies an input alternating current (AC) audio input signal and outputs a power amplified result as an audio output signal, wherein a b-th amplifying terminal (1≦b≦B) comprises: a preamplifier that divides the audio input signal into positive and negative portions, preamplifies the positive and negative portions, and outputs the preamplified positive and negative portions; a power supply to supply positive and negative voltages having different levels; a power amplifier that selects one of the positive supply voltages having a level proportional to a level of the preamplified positive portion and one of the negative supply voltages having a level proportional to the level of the preamplified negative portion, amplifies the preamplified positive and negative portions using the selected one of the positive and negative supply voltages, respectively, and outputs the amplified positive and negative portions; and a signal synthesizer that combines the amplified positive and negative portions output from the power amplifier and outputs the combined result as the audio output signal, wherein said amplifier comprises current amplifiers, each of which is connected to a corresponding one of the positive and negative supply voltages, the preamplified positive portion is amplified using one of the current amplifiers that is connected to the one of the positive supply voltages that is proportional to the preamplified positive portion, and the preamplified negative portion is amplified using another one of the current amplifiers that is connected to the one of the negative supply voltages that is proportional to the preamplified negative portion.