Design Of Configurable Digital Nultibit Sigma-delta Modulator And FPGA Verification

In recent years,digital integration technology of MEMS gyroscope circuits has been widely developed and applied in all kinds of fields about high-precision nuclear detectors,digital audio and video,radar applications,wireless communications,and oil and gas exploration due to it's strong anti-interference ability,high reliability,high performance and low power consumption.Among them,the high-precision DAC is the most active branch in the current research field,which determines the conversion accuracy of the DAC and affects the performance of the entire gyro sensor.The implementation of high-precision DAC generally uses Sigma-Delta modulation technology,so designing high-precision Sigma-Delta DAC digital modulators is of great significance for improving the performance of gyroscope sensors.This design is based on oversampling technology and Sigma-Delta modulation technology to implement a configurable multi-bit quantization Sigma-Delta digital modulator for MEMS gyroscope systems.First of all,this design uses a CIFF structure to implement an order-configurable 4-bit quantized Sigma-Delta digital modulator,based on the design specifications of the modulator and the advantages and disadvantages of various implementation structures of the Sigma-Delta modulator The NTF function is optimized by the local feedback technique,the coefficient CSD coding is optimized,and the stability of the system is analyzed.The SIMULINK system level modeling and simulation results of the Sigma-Delta digital modulator shows that the SNR range of the modulator is 78.8dB-142.2dB,and the effective bit number ENOB range is 12.79bit-23.32bit.On this basis,the RTL implementation and simulation of Sigma-Delta digital modulator are completed.The simulation results of various stages of Sigma-Delta modulator and the corresponding system time domain simulation waveform are compared.It is concluded that this Sigma-Delta modulator can realize the function of multibit quantization Sigma-Delta digital modulator.Secondly,owing to the digital modulator is 4bit quantized,the mismatch errors will be produced.Therefore,this Sigma-Delta digital modulator applies module 16 adder and D trigger form the strobe circuit of the DWA algorithm,which used to reduce the nonlinear error caused by mismatching.Through DWA algorithm system level modeling,verilog code and functional simulation verification,the algorithm can realize DWA function.The Sigma-Delta modulator configurable design was completed for functional verification.Configurability is achieved by adding different carrier signal sampling frequencies,dividing the FPGA 50MHz system clock,and modifying the internal program and parameters of the module to implement different clock frequency signals.The simulation results show that this design can realize the configurability of Sigma-Delta modulator.Finally,we have completed the synthesis and verification of configurable multi-bit quantized Sigma-Delta digital modulators by using FPGA.Specifically,we have analyzed and verified the sinusoidal input signal of the digital modulator,the functional of the digital modulator and the configurable function.The experimental output waveform show that,the SignalTap ? Logic Analyzer indicates the correctness of the digital modulator design.