Low-noise readout IC with integrated analog-to-digital conversion for radiation detection system

A low-noise readout integrated circuit, comprising a charge sensitive amplifier, a pulse shaper with baseline holder, a peak detector and an A/D converter, is presented. The designed IC quantifies optical response of a large-area epitaxial photodiode integrated on a body of a semiconductor scintillator. The input transistor size and the time constant of the shaper are optimized to obtain a minimum equivalent noise charge(ENC) with the large input load capacitance. A time-based clockless A/D converter is implemented to minimize the interference of the digital part of the readout system on the low-noise charge-sensitive amplifier. The simulated ENC of the readout system interfacing a 50 pF capacitance and a dark current of 10 pA that model the epitaxial photodiode is 172 electrons at 12 μs time constant of the pulse shaper with power consumption of CSA and shaper of 2.2 mW.