Multichannel CMOS ASIC preamplifiers for avalanche photodiode and microstrip gas chamber readouts

A 10-channel (Ch) and a 16-Ch application specific integrated circuit (ASIC) preamplifier chip with telescopic-cascode topology and gain-boosted (regulated) cascode topology respectively has been designed for avalanche photodiode (APD) and microstrip gas chamber (MSGC) readouts. These highly integrated and reliable chips can be used for individual readouts from many channels to improve the spatial resolution and counting rate of such detectors over light sharing or charge division schemes. These chips were fabricated on a 2.4 times2.4 mm die area using ROHM 0.35-mu CMOS technology. The chips were tested to have a low optimum equivalent noise charge (ENC) of about 880 e
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at a shaping time of 0.5 mus. The voltage output to charge input gains of the 10-Ch and 16-Ch preamplifiers are 0.71/pf and 0.91/pf while the rise times (10%-90%) are 15 and 13 ns, respectively. The 16-Ch chip was used to readout a GSO-APD detector and an optimum energy resolution of 11.3% (511 Kev peak of Na-22) was obtained while the coincidence time resolution with two such detectors is about 12.5 ns. The energy resolution of the 5.9 keV peak from a Fe-55 source obtained with a 3 times3 cm MSGC plate was about 20.5%