3GSps Track-and-Hold circuit in 0.18 µ m CMOS process

High-speed CMOS Track-and-Hold (T&H) circuit is the key component in the high-speed Analog-to-Digital converter (ADC). It is difficult to implementation GSps T&H in 0.18μm CMOS because of the bandwidth limitation in the OPA. In this paper, a 3GSps open loop T&H circuit in 0.18μm CMOS technology is proposed. The distortions in track mode and injection charge error in the hold mode were analyzed. CMOS switch and a differential buffer are used to trade off the speed, accuracy and sensitivity. Simulation results show that setup time, aperture time, aperture error and voltage drop rate are 280ps, 23ps, less than 3ps and 0.9μV/μs respectively. The T&H can work up to 3GHz at 1.8V supply and it could be used in 3GSps flash ADC in 0.18μm CMOS process.