Development of a compact radiation-hardened low-noise front-end readout ASIC for CZT-based hard X-ray imager

Abstract

In this paper, we present the development and performances of a radiation-hardened front-end readout application-specific integrated circuit (ASIC) dedicated to CZT detectors for a hard X-ray imager in space applications. The readout channel consists of a charge sensitive amplifier (CSA), a CR-RC shaper, a fast shaper, a discriminator and a driving buffer. With the additional digital filtering, the readout channel can achieve very low noise performances and low power dissipation. An eight-channel prototype ASIC is designed and fabricated in 0.35μm CMOS process. The energy range of the detected X-rays is evaluated as 1.45keV to 281keV. The gain is larger than 100mV/fC. The equivalent noise charge (ENC) of the ASIC is 53e− at zero farad plus 10e− per picofarad. The power dissipation is less than 4.4mW/channel. Through the measurement with a CZT detector, the energy resolution is less than 3.45keV (FWHM) under the irradiation of the radioactive source 241Am. The radiation effect experiments indicate that the proposed ASIC can resist the total ionization dose (TID) irradiation of higher than 200krad (Si).