A High-precision Sigma-Delta ADC Modulator For Digital Audio Application

Sigma-delta A/D converters can achieve high resolution based on oversampling technology , noise-shaping technology and digital filtering technology. Comparing with conventional Nyquist A/D conventers, sigma-delta A/D conventers greatly adopt the digital signal processing technology. Additionally, these converters take advantage of the enhanced speed, low-cost and high-integrational advantage of modern VLSI technologies.This work is devoted to the research and realization of a high precise sigma-delta A/D converter. The main contents of this dissertation are listed below.Firstly, the operational principle of sigma-delta A/D converters is studied, and the key technologys of high-precise sigma-delta A/D converters is proposed. Comparing a variety of structures of high-precise sigma-delta ADC, point out the kinds of technical limitations and their solutionsSecondly, intensive study is given to a variety of non-idealities for the electrical implementation and the impact of these non-idealities. The importance increases when the specifications of the sigma-delta modulator are demanding because the can become the main error sources. The power of each error induced by non-idealities is derived, thus it is important to provide the basis for the sigma-delta modulator structure selection and optimization, for that reason the design of the circuit blocks are more targeted.Finally, the high-precise modulator is realized employing switched-capacitor in standard CMOS technology. A two stage operational amplifier is proposed, which achieves high gain of 101dB and high slew rate of 62V/μs. Scaling integrator sampling capacitors down to minimum value required by KT/C noise. A 4bit quantizer, a multi-phase clock generator and a reference current source are also included. The simulation results show that the design satisfy the specification, and also verify the behavior models.