Time-Domain Noise Analysis of 8-Channel CMOS Readout Circuits for CZT X-Ray Detector Array

An 8-channel CMOS low-noise readout IC is designed for CdZnTe (CZT) X-ray detector arrays. Each channel of the IC is composed of a continuously discharged preamplifier and a comparator. The preamplifier is operated in pulse-mode and this is realized with a feedback capacitor and a pair of MOSFETs. The noise of this readout IC is calculated by the time-domain Hspice noise simulation. The calculated RMS total noise voltage at the output node of the preamplifier is 0.246 mV. The prototype chip is fabricated by 1.5 um CMOS technology through MO SIS and the measured noise voltage of the preamplifier output is 0.435 mV.