Research On Quantization Noise Shaping Technology Based On MASH Structure ?? Modulator

High-speed and high-precision modulators are an indispensable component of ultra-high-speed ultra-wideband communication systems,but there are some questions for current communication systems such as ultra-wideband communication systems,orthogonal frequency division multiplexing systems,and 5G millimeter-wave communication systems.The sampling rates is too high to be implemented and the noise shaping method cannot meet the system requirements.Therefore,the study of modulators with ?? modulator as the core provides a new effective solution to break the limitations of the development of wireless communication systems.In this paper,the basic theory of multistage noise shaping(MASH)structure ?? modulator is studied.Under the condition of low oversampling rate,the traditional two-stage MASH structure is improved by applying noise shaping technology.Three kinds of MASH topologies with better quantization noise shaping effects are proposed respectively.Firstly,an improved two-stage MASH structure is proposed by studying the traditional two-stage MASH structure.The new two-stage MASH structure not only improves the way of extracting the first-stage quantization noise,but also introduces two-order feedforw ard in the second-stage structure.The final output signal is that the extracted first-order noise is used as the input signal of the second stage and finally eliminated,and the second-order quantization noise is subjected to fourth-order shaping.A better noise shaping effect is achieved with reduced overall hardware cost and implementation difficulty.Secondly,a two-stage MASH structure modulator with inter-stage feedback and a low distortion structure are studied.The active adder in the low distortion structure is eliminated and applied to a two-stage MASH structure modulator with interstage feedback.The proposed structure is achieved only by using an improved low distortion structure and an additional analog path.The traditional MASH structure modulator has a higher order noise shaping effect.Therefore.it is also possible to achieve a higher signal-to-noise ratio with a minimum of extra circuitry.Finally,a MASH structure modulator with analog noise coupling is proposed.The proposed MASH structure modulator feeds the second stage quantization noise through the delay unit to the input of the second stage quantizer.Therefore,the output of the quantizer contains the input signal of the second stage of the modulator and the second stage of quantization noise with a first order shaping effect.This improves the effect of quantization noise shaping and does not affect the stability of the loop.In this paper,the improvement effects of the three modulators are introduced in detail,and the structure before and after the improvement is theoretically deduced.The simullink module of MATLAB is used to simulate the simulation.The simulation results also show that the three improved structures have higher quantization noise.Shape function and quantized signal to noise ratio.