Digital audio PDM (pulse duration modulation) signal DC (direct current) filter circuit

Abstract

The invention discloses a digital audio PDM (pulse duration modulation) signal DC (direct current) filter circuit, comprising a first-order infinite impulse response high pass filter and a second-order sigma-delta modulator, wherein the first-order infinite impulse response high pass filter is used for filtering DC components in PDM signals input to the digital audio PDM signal DC filtering circuit and converting single-bit PDM signals input to the digital audio PDM signal DC filter circuit into multi-bit data; the second-order sigma-delta modulator is used for converting the multi-bit data output from the first-order infinite impulse response high pass filter into 1.5-bit PDM data; the input end of the second-order sigma-delta modulator is connected with the output end of the first-order infinite impulse response high pass filter. According to the digital audio PDM signal DC filter circuit, the DC filtering for the digital audio PDM signals can be realized by filtering the DC components in sigma-delta AD (analogue-digital) output PDM signals.

Description

technical field [0001] The invention relates to the technical field of signal processing algorithms and integrated circuits, in particular to a digital audio PDM signal DC filter circuit applied to audio systems. Background technique [0002] With the improvement of people's living standards, many people, especially audio enthusiasts, have almost strict requirements on whether the audio power amplifier can restore the sound perfectly and without distortion. The analog power amplifier has been developed for decades, and the technology in this area has been quite mature, and it can be said that it has reached the pinnacle. Environmental protection and energy utilization have gradually become people's concerns. Because of this, consumers have higher and higher requirements for power amplifier efficiency, and analog power amplifiers have almost reached the limit in this regard. Power amplifiers are usually divided into five categories according to their working status. That is...

AI Technical Summary

Problems solved by technology

In the class D digital amplifier, the input signal needs to be modulated to output PWM signal or PDM signal. The DC signal in the input signal will cause the modulator to be overloaded, which will affect the output power and even affect the function of the entire amplifier.

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