Design of a Multi-Channel Low-Noise Readout ASIC for CdZnTe-Based X-Ray and $\gamma $-Ray Spectrum Analyzer

In this paper, we report on the recent development of a 32-channel low-noise front-end readout ASIC for cadmium zinc telluride (CdZnTe) X-ray and
$\gamma $
-ray detectors. Each readout channel includes a charge sensitive amplifier, a CR-RC shaping amplifier and an analog output buffer. The readout ASIC is implemented using TSMC
$0.35 - \mu \hbox{m}$
mixed-signal CMOS technology, the die size of the prototype chip is
$2.2~\hbox{mm} \times 4.8~\hbox{mm}$
. At room temperature, the equivalent noise level of a typical channel reaches
$133~\hbox{e}^ - ({\rm rms})$
with the input parasitic capacitance of 0 pF for the average power consumption of 2.8 mW per channel. The linearity error is less than
$ \pm 2\% $
and the input energy dynamic range of the readout ASIC is from 10 keV to 1 MeV. The crosstalk between the channels is less than 0.4%. By connecting the readout ASIC to a CdZnTe detector, we obtained a
$\gamma $
-ray spectrum, the energy resolution is 1.8% at the 662-keV line of
$^{137}{\rm Cs}$
source.