Class-D audio power amplifier circuit

Abstract

The invention relates to a class-D audio power amplifier circuit. Two input ends of a first-stage amplifier are connected with audio signals, two output ends of the first-stage amplifier are connected with two input ends of a second-stage amplifier after being connected with an input resistor in series, and two feedback resistors are connected with the two pairs of input ends and output ends of the first-stage amplifier; one output end of the second-stage amplifier is connected with a first comparator in series, a first drive circuit is connected with one input end of a loudspeaker, another output end of the second-stage amplifier is connected with a second comparator in series, and a second drive circuit is connected with another input end of the loudspeaker; and two feedback capacitors are connected with the two pairs of input ends and output ends of the second-stage amplifier, and two feedback resistors are connected with the input ends of the second-stage amplifier and the input ends of the loudspeaker. The dominant pole of the circuit is controlled by using the second-stage feedback resistors and feedback capacitors to ensure that the audio signals can be amplified and other high-frequency components can be inhibited. Meanwhile, two loops can effectively increase the power supply rejection ratio of the circuit and reduce total harmonic distortion.

Description

[technical field] [0001] The present invention relates to integrated circuit design, in particular to class D audio power amplifier circuit design. [Background technique] [0002] In the known class D audio power amplifier circuit, after the audio input is amplified by the first-stage amplifier and the second-stage amplifier, the amplified result is compared with the triangular wave, and the square wave generated by the comparator is input to the drive circuit to start the speaker. The audio signal will generate total harmonic distortion (THD) during this transmission process, and will also be affected by power supply ripple (PSRR). The way to suppress noise and reduce total harmonic distortion is mainly to design precise circuits and increase large filter capacitors, so as to improve the power supply suppression capability of the chip and reduce total harmonic distortion, but precise circuits and large filter capacitors require a large area Even in such a circuit, there wi...

AI Technical Summary

Problems solved by technology

The audio signal will generate total harmonic distortion (THD) during this transmission process, and will also be affected by power supply ripple (PSRR)

The way to suppress noise and reduce total harmonic distortion is mainly to design precise circuits and increase large filter capacitors, so as to improve the power supply suppression capability of the chip and reduce total harmonic distortion, but precise circuits and large filter capacitors require a large area Even in such a circuit, there will still be a certain amount of noise and total harmonics due to process mismatch during signal transmission, ripple voltage of the power supply, substrate bias effect, and other parasitic effects of the circuit. Wave distortion, these noises and total harmonic distortion will be amplified by operational amplifiers, comparators and drive circuits, and there will still be relatively large noise and total harmonic distortion on the speaker

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