Front End Track and Hold Circuit for High Speed Analog to Digital Converters

Source follower based open loop track and hold circuits are commonly employed at front end of pipelined analog to digital converters. Performance of such track and hold degrades at higher operating frequencies due to non linearity arising due to non ideal MOS switches. In present work, conventional open loop track and hold circuit is implemented and its performance is improved by adopting two switch linearization techniques: voltage bootstrapping and gate voltage boosting. Based on these two techniques, another bootstrapped switch is proposed which operates at voltage higher than Vdd. Track and hold with proposed switch produces low distortion and can provide 9 bit static linearity at 500 MHz clock and suitable for high resolution high speed analog to digital converters.