Patent ID: 7102414

Claim:
A muting circuit for audio amplifier, comprising a basic differential amplifier, wherein the basic differential amplifier having a first pair of MOS transistor to form a first differential pair, and having a second pair of MOS transistor to form a current mirror, the first pair of MOS transistor is connected with the second pair of transistor respectively, two gates of the first differential pair are an input and an output of the audio amplifier respectively; a third pair of MOS transistor forming a second differential pair, the third pair of MOS transistor is connected with the second pair of transistor respectively, two gates of the second differential pair are connected with a bias and the output of the audio amplifier respectively; two additional sets of MOS transistor switch control the first differential pair and the second differential pair respectively; a muting signal controls one of the two additional sets of MOS transistor switch through an inverter, while controls the other of the two additional sets of MOS transistor switch via two inverters connected seriesly, so that the muting signal is able to open/close the first differential pair or the second differential pair to form a muting effect.