Research And Design On The Analog Circuit Of 16 Bits Sigma-delta ADC

With the development of electronic technology,AD converter arises higher and higher requirement to precision,Σ-△modulator structure has so far been the most attractive ways to execute high precision.Sigma-delta conversion technology is based on oversampling,noise shaping,and decimation filtering.Σ-△ADC can achieve high resolution based on oversampling and noise-shaping.Comparing with conventional Nyquist converters,Σ-△converters greatly release the requirements for high performance of analog circuit and precisely match components.And,these converters exploit the enhance speed,circuit density and low cost of modern VLSI technologies.Also,the major advantageis that it is based predominantly on digital signal processing due to its digital nature sigma-delta converters can be integrated onto other digital devices.Manufacture technology is not withstanding,hence the cost of implementation is low and will continue to decrease.It is the greatest advantage of all in the cost.The paper research and design is analog circuit of a 16 bitΣ-△converter.Based on the theory of sigma-delta,it designs two order sigma-delta modulations.The experimental modulator carried out with fully differential switched-capacitor circuit.And the ways to optimize the circuit architecture are to minimize integrator nonidealities,comparator nonidealities,resistance of switch nonzero and circuit noise in the system.At the same time,this paper designs the every module in the circuit.It includes the design of circuit CMOS operation,band-gap,differential switched-capacitor circuit,comparator, nonoverlapping clock and feedback DAC.The paper gives simulation result of each module and the whole module,it validates through cadence and realizes the precision of 16 bit ADC.