2-2 MASH结构改进及其FPGA实现

Improvement of 2-2 MASH Architecture and Implementation with FPGA

针对多级噪声整形(Multi-stage Noise Shaping, MASH)结构的量化噪声问题,提出一种在传统MASH结构基础上改进的4阶两级MASH结构.首先分析传统MASH结构的原理,指出在输入信号延时处理上的不足,进而给出改进的MASH结构及理论分析.利用Altera公司的StratixⅡ系列FPGA采用自顶向下的方法构建二阶单环调制器模拟部分、噪声抵消单元数字部分和数据处理部分等主要模块实现本文的MASH结构.仿真表明,改进的MASH结构较传统结构减少67%的延时,噪声整形性能比改进前提升9.7%,进一步降低量化噪声的影响.

To solve the problem of quantization noise in multi-stage noise shaping(MASH) structure,an improved 4-bit two-stage MASH structure is present based on a typical MASH structure. We first gives the principle of typical MASH structure, and points out that the lack of processing in the input signal delay, then the improved MASH structure and theoretical analysis is given. The MASH structures is implemented by Altera corporation Stratix IV series FPGA, and used top-down method to build the analog part of second-order modulator, the digital part of noise cancellation unit and data processing part of the main modules. Simulations show that the improved MASH structure is 67% less than the traditional structure, and the quantization noise shaping performance is 10% higher than before, and the quantization noise impact is further reduced.