Precision Sigma-delta A / D Conversion Technology Research And To Achieve

With over sampling and noise shaping, base band quantization noise in Sigma-Delta ADC (analog to digital converter) can be depressed. Quantization noise with circuit noise outside base band is removed by digital filter and the burden rest on the digital filter now. Instead of requiring high performance analog circuit, Sigma-Delta technology could improve the signal to noise ratio and dynamic range of the converter. With the outstanding high dynamic and robustness, Sigma-Delta technology could be used in low frequency and audio application.This paper is based on the production of project"new structure of high performance A/D data conversion". The theory and key point of Sigma-Delta technology is embodied in this paper. Based on the results of calculation and simulation, many structures of high performance Sigma-Delta technologies are compared according to the related localization and advantages.The behavior model of Sigma-Delta ADC is included in this paper. Not only the idea modulator and filter models but also the non-idealities of analog circuit are included. The effects of non-ideality of analog circuits on the performance of modulation are analyzed in detail. According to the spec, a second order three bit (quantization with 9 levels) modulator with max SNR 100dB is designed. This design includes the optimization of system structure, SNR (signal to noise ratio), dynamic range, and bandwidth. Analog circuits which satisfy the behavior simulation results are designed, including full differential operation amplifier, FLASH ADC, switched capacitor integrator, FLASH DAC, DWA (Data weighted averaging) circuit and clock generator. The circuits are simulated with HSPICE and the results are analyzed with MATLAB. Simulation results show that the design satisfy spec which also verify the behavior models.