Research And Design Of High Precision And High Energy-efficiency Sigma-delta Modulator

Currently,high-precision Sigma-Delta ADC is widely used in various fields such as high-quality audio,precise instrumentation equipment and sensor interface.Since the sampling frequency of high-precision Sigma-Delta ADC needs to be much higher than the operating bandwidth,high-precision Sigma-Delta ADC mainly focus on conversion of low-and mid-frequency signals(<100 kHz)for keeping system power consumption reasonable.However,with the advancement of technology,more and more application scenarios that require ultra-high-precision analog-to-digital conversion of larger-bandwidth signals gradually appear.Following this trend,current research direction of high-precision Sigma-Delta ADC gradually focuses on reducing power consumption of the system while maintaining its accuracy and speed,that is,improving energy-efficiency of ADC.Since power consumption of a typical Sigma-Delta ADC mainly concentrates in Sigma-Delta modulator,this thesis aims to implement a high-precision,high energy-efficiency,discrete-time Sigma-Delta modulator.This thesis firstly selects the most energy-efficient architecture,which is single-loop high-order multi-bit with feedforward topology,based on the analysis and comparison among several mainstream architecture.Secondly,considering the difficulties in implementing this architecture such as summation circuit and feedback DAC mismatch correction module,corresponding energy-efficient circuit-level solutions are proposed.Finally,this thesis completes the design of the overall circuit from schematic-level to layout-level based on 180 nm CMOS process,and extracts parasitic parameters for post-simulation performance verification.Post-simulation results indicate the modulator achieves a 111.5 dB signal-to-noise and distortion ratio within 100 kHz bandwidth under 1.8 V core supply voltage and 3.3 V reference voltage while consumes 28.3 mW power.This modulator reaches 177.0 dB Schreier figure of merit(quantity index of energy-efficiency)at post-simulation,which is a prominent level among published state-of-the-art designs.