class d power amplifier

Abstract

The invention relates to a Class D power amplifier which comprises a sigma delta modulator, a switch logic circuit, a full-bridge output power tube circuit and an output common mode voltage correcting circuit, wherein the output common mode voltage correcting circuit comprises a voltage extraction circuit, a common mode correcting integrator and a comparator; the voltage extraction circuit is formed by series connection of two resistors and used for extracting common mode signals from differential signals; the two ends of the voltage extraction circuit are connected with the two differential signals respectively; the common ends of the two resistors in the voltage extraction circuit are connected with a positive input end of the common mode correcting integrator; a negative input end of the common mode correcting integrator inputs a preset reference level signal; an output end of the common mode correcting integrator is connected with an input end of the comparator; and an output end of the comparator is connected with the switch logic circuit. The amplifier effectively solves the problem of deterioration of a signal to noise ratio, is concise in circuit structure and lower in power consumption, facilitates monolithic integration and has the characteristic of high efficiency.

Description

technical field [0001] The invention relates to a class D power amplifier, in particular to a class D power amplifier using an output common mode voltage correction circuit. Background technique [0002] In recent years, with the development of digital technology, most audio formats and the entire audio chain are fully digitalized. In fields such as CDs, Mp3 players, smartphones, tablets, the Internet, music and voice signals are transmitted and stored digitally. The traditional method of driving a speaker with a digital signal involves two steps, first converting it to an analog signal and then amplifying it to an appropriate level. These operations are realized by cascading a class AB audio amplifier with a high-performance digital-to-analog converter (DAC). However, generally speaking, class AB amplifiers have relatively low power efficiency, which affects the battery life of the system and increases heat dissipation. Therefore, a lot of research in recent years has tu...

AI Technical Summary

Problems solved by technology

However, the traditional three-level switch faces the problem of output common-mode voltage variation: when the output is "0" state, the two differential outputs of the full-bridge output power transistor will be pulled to the ground (VSS) or the power supply voltage (VDD) at the same time. ), the output common-mode voltage at this time is VSS or VDD; and when the output is in the "+1" or "-1" state, one of the two differential outputs of the full-bridge output power transistor is pulled to VDD, and the other is pulled to to VSS, the output common-mode voltage at this time is (VDD+VSS)*0.5

Literature [2] uses a capacitor that stabilizes the output common-mode voltage to ensure that the common-mode voltage is always (VDD+VSS)*0.5, but the area of ​​the capacitor is large, which is not convenient for monolithic integration

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