Patent ID: 8643434
Filing Date: 2014-02-04
Classification: H03G

Abstract:
1. An adjustable gain audio power amplifying circuit comprising an input unit, an audio amplifying unit connected to said input unit, a gain adjusting unit connected to said audio amplifying unit, a controlling unit connected to said gain adjusting unit, a comparing unit connected between said gain adjusting unit and said controlling unit and an output unit connected to said audio amplifying unit, wherein said comparing unit is for comparing an outputted signal of said output unit with a common-mode reference voltage, outputting a gain adjustment controlling signal and sending the gain adjustment controlling signal into said controlling unit; when the outputted signal equals the common-mode reference voltage, the gain adjustment controlling signal turns over and then said controlling unit detects the turnover of the gain adjustment controlling signal, receives a gain adjustment signal and sends the gain adjustment signal into said gain adjusting unit; based on the received gain adjustment signal, said gain adjusting unit controls gains of said adjustable gain audio power amplifying circuit.