Design Of A High Precision Multi Bit Quantization Sigma Delta DAC

Since the 21 st century,the market of audio electronic products has been growing rapidly.In high quality audio system,high precision DAC is one of the key modules.This paper is to study a high-precision sigma delta DAC digital front-end implementation for audio system.The work of this paper includes two main modules: interpolation filter and digital sigma delta modulator module.The interpolation filter module is realized by half band filter,compensation filter and sampling holder.Based on the analysis of traditional half band filter,a robust multiplexing filter structure is proposed.The structure improves the transfer function of traditional half band filter,reduces the sensitivity of amplitude frequency characteristics to filter coefficients,and has the characteristics of low hardware resource consumption and fast speed.When realizing the coefficient of the multiplexing robust half band filter,a new one is proposed The algorithm uses the basic formula between coefficients to share resources,and achieves the goal of reducing logical operands.The optimization from structure to coefficient will inevitably save more hardware resources than the traditional implementation method;the sampling holder is realized by CIC integral comb filter,while CIC integrated comb filter will filter high-frequency noise and attenuate the signal in the bandwidth,so it adopts the complement The compensation filter compensates the CIC integrated comb filter,and when the digital bit stream output is high precision,a digital Sigma with multi quantization cascade structure is designed in this paper Delta modulator,in order to solve the problem of low SNR caused by mismatching at all levels in traditional mash structure,this paper uses the first-order phase accumulator to realize the traditional mash structure,which fundamentally solves the mismatch between different levels.In this paper,through the in-depth study of the theory of sigma delta DAC,the front-end circuit of the whole sigma delta DAC is implemented in hardware.Finally,the comprehensive simulation is carried out through FPGA.A total of 847 le and1856 bit embedded RAM are used,and the circuit scale is 15894 gates.In the audio bandwidth,the signal-to-noise ratio is 153.2db,and the significant bits reach 25.123,which achieves the expected design target.