Digital filtering device and method used for pulse width modulation signal

Abstract

The application discloses a digital filter device and method used for a pulse width modulation signal. The digital filtering device comprises a first filter, a second filter, a storage device, a multiplier and a data controller. The first filter is used for carrying out low-pass filtering of a pretreatment signal of the pulse width modulation signal to generate a first intermediate signal. The second filter is used for carrying out high-pass filtering of the first intermediate signal to generate audio data. The storage device is used for storing parameter values and historical values of the first filter and the second filter. The multiplier is used for carrying out multiplication according to the parameter values and the historical values so as to carry out filtering. The data controller is used for connecting the storage device and the multiplier with the first filter and the second filter in a time sharing mode respectively, so as to carry out filtering. The digital filtering device can reduce the power consumption, the chip size and the cost by using shared modules.

Description

technical field [0001] The present invention relates to signal processing techniques, and more particularly, to digital filters and methods for pulse width modulated (PDM) signals. Background technique [0002] In signal processing, an analog-to-digital converter is used to convert the analog signal into a digital signal, and then the digital signal is modulated to generate a digital modulation signal, and the digital modulation signal is filtered to remove quantization noise, thereby obtaining a low-noise digital signal. Signal processing chips integrating analog-to-digital converters and modulators are already available on the market. For example, a digital microphone chip has an internal sigma-delta analog-to-digital converter dedicated to processing audio signals, where the analog signal is converted into a pulse-width modulated (PDM) format. PDM signals include oversampled one or more bits (eg, 2 to 4 bits) signals. The relative pulse width of the PDM signal can chara...

AI Technical Summary

Problems solved by technology

[0005] The above-mentioned existing digital filters may include multiple FIR filters and multiple IIR filters, which require high-frequency reading and writing of memory and multiplication operations in digital signal processing, resulting in prolonged operation time and loss of system power consumption

Due to system clock constraints, each FIR filter and each IIR filter requires a separate multiplier and memory, resulting in increased die size and cost

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