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ADC modulus as a generic interface circuit , which is widely used in mixed analog-digital circuits. As digital signal processing technology and the level of integrated circuit technology driven ADC is moving faster conversion speed , higher precision , lower power consumption , smaller area, and other direction. Due to the pipelined analog to digital converter in speed, accuracy , power consumption, has a good balance , can achieve high speed , high resolution , it has been widely used . Sample and hold circuit is pipelined ADC a crucial module, which determines the accuracy and speed of the whole system can achieve maximum performance. Conventional sample and hold circuit through the feedback network with a high gain , high-speed charge transfer precision op amp . However, with the reduction in the size of integrated circuit technology , the device reduces the inherent gain , design a high-gain , high-speed op amps and more difficult , this paper presents a new sample and hold circuit , is based on the zero-crossing detector the sample and hold circuit . This circuit speed is fast , simple structure , to avoid high gain , high speed op amp design and realized based on the traditional op amp sample and hold circuit the same function. This paper analyzes the pipelined ADC basics , then cadence environment, the use SMIC0.18um technology, design and simulation of a pipelined ADC sub-circuit modules, including CMOS switch , zero-crossing detector , comparator, etc. , and then based on simulation zero-crossing detector pipelined ADC sample and hold circuit , simulation results show that the power supply voltage of 1.8V , when the input frequency is 1.9938MHz, the amplitude of the sine wave is 0.15V , the sampling frequency is 40MHz , the sample and hold circuit Settling time is 5ns, spurious-free dynamic range is 58.12dB, power dissipation is 300.88uW, showed sample and hold circuit is fully applicable to six 40MHz sampling pipelined ADC front-end part , which is pipelined ADC's sample and hold circuit designed to provide a new idea , and then paper -based simulation of MDAC zero-crossing detector circuit , sub- ADC circuit and single-stage pipeline ADC circuit , papers finalized based on zero-crossing detector sample and hold circuit layout and post-simulation .
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