Design of a Prototype Readout Electronics System for CZT Detectors in Solar X-ray Observation

The X-ray Imaging Telescope (XIT) is one of the scientific payloads of the Solar Polar Observatory (SPO), primarily tasked with solar X-ray observations. It aims to monitor full-disk eruptive events and obtain X-ray spectra of small-scale solar activities. CdZnTe (CZT) crystals, known for their lightweight nature, high average atomic number, and large photon interaction cross-section, have been widely used in multiple space astronomical satellite payloads. To meet the prototype validation requirements of the XIT payload, this paper designs and implements a prototype readout electronics system for CdZnTe detectors. The system employs the Application-Specific Integrated Circuit (ASIC) VATA461.3 chip to acquire and process signals from CdZnTe detectors. The chip is a special chip for charge measurement, with low power consumption, low noise, and high integration, suitable for space missions. In this paper, the hardware design of the detector readout electronics, the firmware development of the FPGA, and the implementation of the host computer software, have been achieved. Experimental test results indicate that the equivalent noise charge (ENC) of the system ranges from 154 to 201 e⁻. The integral non-linearity (INL) of the 32 channels is better than 4.33%. The energy resolutions of large and small pixels are 3.94 keV@59.5 keV and 3.14 keV@59.5 keV, respectively, both satisfying the technical requirement of 4 keV@59.5 keV.