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

A CMOS charge sensitive readout chain with self switched output and small layout area, suitable for pixel applications, has been developed. The system is capable of simultaneous position sensing and energy measurement on a real time basis. Each pixel circuit incorporates both analog and digital features 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 investigated. The read out electronics have been designed and fabricated in CMOS 0.8 μm technology. The overall gain of the chain is 620 mV/fC, while the ENC is 58 e rms at a 140 nsec shaping time and a 105 fF detector capacitance. With a power consumption of 1.8 mW per pixel at 3.3 V, it is a promising solution for X-ray pixel detectors. The paper describes the system architecture and reports experimental measurements