Bit Control Of Sigma Delta Modulator

With the development of science and technology and the further research on Sigma Delta modulator,the Unit High-order Sigma Delta modulator is also widely used in real life,it consists of a high-order loop filter with negative feedback structure and a unit quantizer.However,the loop filter of the modulator is non-bounded output stable,which will lead to the modulator imbalance.In order to make the modulator run stably,the noise transfer function in the signal band can be obtained by a reasonable design of the loop filter and the noise can be concentrated outside the signal band,in addition,the signal transfer function with small amplitude outside the band can be obtained and the signal is concentrated in the band,thus the signal and noise in different bands can be obtained.The sampling process can be directly completed by existing hardware,so this type of modulator is often used to achieve audio products analog-to-digital conversion process.This thesis is an extension of the existing frequency domain bit-flipping control theory for stabilizing unit high-order interpolated Sigma Delta modulators,in this thesis,the operating principle,performance index and structure of Sigma Delta modulator are briefly analyzed,and then the implementation scheme of the control strategy is proposed and its performance is evaluated.Because the frequency domain bit-flipping control strategy mainly aims at limiting the frequency content of the input sequence of the modulator,the frequency detector can be used to detect the resonant frequency of the input sequence of the Sigma Delta modulator,neural network is used to solve the problem of integer programming.Finally,buffer,combinational logic gate and inverter are used to realize the control strategy.For the performance evaluation aspect,the stability region can be evaluated based on the range of the input dynamics.The results show that the control strategy can significantly improve the dynamic range of input from 0.24 to 0.58.In addition,compared with clipping control strategy,this control strategy can be applied to a wider range of input signal types.