A SAR ADC For Array Pressure Sensing

A 12-bit single-ended successive approximation analog-to-digital converter (SAR ADC) is designed for the acquisition of multiple signals of pressure sensor arrays as well as for processing. The proposed SAR ADC has a bridge capacitor for the DAC to save chip area, uses a lower level board sampling technique to eliminate the effect of nonlinear charge injection and clock feedthrough on sampling, and uses a three-stage preamplification plus latch structure for the comparator to reduce kickback noise and introduces an output detuning storage technique to reduce comparator detuning and improve comparison speed. The circuit is designed using UMC 0.18um 1.8V CMOS process. Simulation results show that the designed SAR ADC can achieve an effective number of bits (ENOB) of 11.46 at 200kSPS sampling frequency with an average power consumption of 0.35mw, which can be applied to the front-end processing of signals from pressure sensing arrays.