一种3阶Mash结构的Σ-Δ音频数模转换器

A Σ-Δ Audio DAC Converter Based on 3-Order Mash Structure

针对传统的Mash结构由于各级失配导致信噪比低的问题,本文采用一阶相位累加器来实现传统的sigma-delta(Σ-Δ)架构,并将其采用硬件描述语言来实现,这样整个系统均在数字域实现,从根本上解决了各级间的失配问题.在插值滤波器的设计上,使用优化了的半带滤波器结构和级联积分梳状滤波器,节省了硬件资源.电路采用的是Magnachip 180nm 1P4M标准CMOS工艺,芯片面积只有0.2025mm^2(0.45×0.45),实测芯片得到的信噪失真比(SNDR)达到90d B.

To solve the problem that the traditional Mash structure has low signal-to-noise ratio because of mismatch at each levels,in this paper,the traditional sigma-delta （ Σ- Δ ） structure is realized by using the phase accumulator,which is easy to realize the hardware description language of the whole system,thus fundamentally solving the mismatch between the different stages.In the design of the interpolation filter,the use of optimized half-band filter structure and cascaded integral comb filter,saving hardware resources.The circuit uses the Magnachip 180nm 1P4M standard CMOS process,the chip area is only 0.2025mm 2 （0.45×0.45）,the measured chip Signal to Noise and Distortion Ratio（SNDR） to 90dB.