A low noise small area self switched CMOS charge sensitive readout chain

A CMOS charge sensitive readout chain with self switched output and small l ayout al ea, suitable for pixel applications, has been developed. The syste m is capable of simultaneous position sensing and energy measurement on a r eal time basis. Each pixel circuit incorporates both analog and digital fea tures to perform the dual task. The performance of several charge amplifiers was tested. The impact of type and channel length of the input transistor on the system noise was investi gated. The read out electronics have been designed and fabricated in CMOS 0 .8 mu m technology. The overall gain of the chain is 620 mV/fC, while the E NC is 58 e(-) rms at a 140 nsec shaping time and a 105 fF detector capacita nce. With a power consumption of 1.8 mW per pixel at 3.3 V, it is a promisi ng solution for X-ray pixel detectors. The paper describes the system archi tecture and reports experimental measurements.