Design and measurement of a low-noise 64-channel front-end readout ASIC for CdZnTe detectors

In this paper, we report on the recent development of a 64-channel low-noise front-end readout ASIC for cadmium zinc telluride detectors aimed to X-ray and γ-ray imaging systems. There are 64 readout channels and 2 test channels in this ASIC. The readout ASIC is implemented in TSMC 0.35-μm mixed-signal CMOS technology, the die size of the prototype chip is 2.7 mm × 8.0 mm. At room temperature, the equivalent noise charge of a typical channel reaches 66 e
^-
(rms) for the zero input capacitance with the average power consumption of 8 mW per channel. The linearity error is less than 1%. The overall gain of the readout channel is 200 mV/fC. The inconsistency among the channels is less than 2.86%. By connecting this readout ASIC to an 8×8 pixel CdZnTe detector, we obtained a γ-ray spectrum, the energy resolution of which is 4.5% at the 59.5-keV line of
²⁴¹
Am source.