Left-growth double-edge UPWM signal frequency spectrum estimation method based on digital PWM generator

Abstract

The invention provides a left-growth double-edge UPWM (Uniform-sampling Pulse Width Modulation) signal frequency spectrum estimation method based on a digital PWM generator. The method comprises the steps of: performing discretization and quantization of a left-growth double-edge second-level UPWM signal output by a digital PWM generator on a time domain to obtain a series of discrete points; adopting the distribution rule of the amplitudes of the obtained discrete points, performing discrete Fourier transform for the discrete points, and multiplying a transform result by the frequency response function of a zero-order keeper, so that a left-growth double-edge second-level UPWM signal spectrum estimation expression is obtained. The second-level UPMW signal spectrum estimation expressions obtained by modulating the input signals of the digital PWM generator before and after the inversion of the input signal are subtracted to obtain a corresponding third-level UPWM signal spectrum estimation expression. The method provided by the invention can directly obtain the frequency spectrum of the left-growth double-edge UPWM signal under the condition that the input modulation signal is a digital signal.

Description

technical field [0001] The invention relates to the field of digital class D audio power amplifiers, in particular to a method for estimating the frequency spectrum of a left-increasing double-edge uniform sampling pulse width modulation signal modulated by a digital audio signal. Background technique [0002] The power efficiency of digital class-D audio power amplifier is higher than that of linear audio power amplifiers such as class A, class B and class AB, and digital class-D audio power amplifier also has the advantage of being able to directly interface with digital audio sources, so it has become a research hotspot in the field of power amplifiers. The structure diagram of digital class D audio power amplifier is as follows: figure 1 As shown, it usually consists of a digital interpolation filter, a Sigma-Delta modulator, a digital pulse width modulation (Pulse Width Modulation, PWM) generator, a power stage and an analog low-pass filter. exist figure 1 Among them,...

AI Technical Summary

Problems solved by technology

However, this method is also not applicable when the modulating signal is a digital signal

According to the above analysis, when the modulating signal is a digital signal, there is no relevant literature that gives an accurate expression for UPWM signal spectrum estimation

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