Adjustable gain audio power amplification circuit

Abstract

An adjustable gain audio power amplifying circuit includes an input unit, an audio amplifying unit connected to the input unit, a gain adjusting unit connected to the audio amplifying unit, a controlling unit connected to the gain adjusting unit, a comparing unit connected between the gain adjusting unit and the controlling unit and an output unit connected to the audio amplifying unit. The comparing unit compares an outputted signal of the output unit with a common-mode reference voltage, outputs a gain adjustment controlling signal and sends the gain adjustment controlling signal into the controlling unit. When the outputted signal equals the common-mode reference voltage, the gain adjustment controlling signal turns over and then the controlling unit detects the turnover and sends a received gain adjustment signal into the gain adjusting unit. Based on the received gain adjustment signal, the gain adjusting unit controls gains of the adjustable gain audio power amplifying circuit.

Description

technical field [0001] The invention relates to an amplifying circuit, in particular to an adjustable gain audio frequency power amplifying circuit with a zero-crossing detection function. Background technique [0002] In the audio power amplifying circuit, when the gain is adjusted, the output signal of the audio power amplifying circuit often jumps, which is easy to cause impact on the speaker or earphone and produce crackling sound, which makes sensitive ears very uncomfortable. . Such as figure 1 The audio power amplifying circuit in the prior art shown is a simulated waveform of the output signal when the gain adjustment is performed, from which it can be seen that the output signal has obvious jumps. [0003] Therefore, it is necessary to provide an adjustable-gain audio power amplifying circuit capable of effectively suppressing the crackle generated by gain adjustment, so that the output signal of the audio power amplifying circuit will not jump during gain adjustm...

AI Technical Summary

Problems solved by technology

[0002] In the audio power amplifying circuit, when the gain is adjusted, the output signal of the audio power amplifying circuit often jumps, which is easy to cause impact on the speaker or earphone and produce crackling sound, which makes sensitive ears very uncomfortable.

Images