POWER AMPLIFIER CIRCUIT WITH MUTE FUNCTION

摘要

PURPOSE: A power amplifier circuit is provided to have mute function of removing pop noise by making DC potential maintained while an output of the circuit is muted. CONSTITUTION: A power amplifier circuit comprises an input signal amplifier(100) which amplifies an input signal(Vin) to output an amplified result via an output terminal(VOUT). A dummy amplifier(120) is driven when a mute control signal(mute) is enabled, and outputs a voltage having a constant DC level via an output terminal(VOUT) in a mute-on state. A mute controller(130) controls so that an input signal of an alternative current is outputted or blocked depending on the mute control signal. A current mirror(140) is supplied with current corresponding to a bias voltage(VBIAS1) via resistors(R2-R5) from a power supply voltage. A gain adjusting part(150) adjusts a loop gain according to a rate of a resistor(R11) to a feedback resistor(R13). A power amplification part(160) amplifies a signal outputted via the output terminal(VOUT).