IDeF-X HD: A CMOS ASIC for the Readout of Cd(Zn)Te Detectors for Space-Borne Applications: A CMOS ASIC for the Readout of Cd(Zn)Te Detectors for Space-Borne Applications

IDeF-X HD is a 32-channel analog front-end with self-triggering capability optimized for the readout of 16×16 pixels CdTe or CdZnTe pixelated detectors to build a low power micro-gamma camera. IDeF-X HD has been designed in the standard AMS CMOS 0.35μm process technology. Its power consumption is 800μW per channel. The energy range of the ASIC can be extended to 1.1MeV thanks to the in-channel adjustable gain stage. When no detector is connected to the chip and without input current, a 33 electrons rms ENC level is achieved after shaping with 10.7μs peaking time. Spectroscopy measurements have been performed with CdTe Schottky detectors. We measured an energy resolution of 4.2keV FWHM at 667keV (137Cs) on a single-pixel configuration. Meanwhile, we also measured 562eV and 666eV FWHM at 14keV and 60keV, respectively (241Am) with a 256 small pixel array and a low detection threshold of 1.2keV. Since IDeF-X HD is intended for space-borne applications in astrophysics, we evaluated its radiation tolerance and its sensitivity to single event effects. We demonstrated that the ASIC remained fully functional without significant degradation of its performances after 200 krad and that no single event latch-up was detected putting the linear energy transfer threshold above 110MeV/(mg/cm2). Good noise performance and radiation tolerance make the chip well suited for X-rays energy discrimination and high energy resolution. The chip is space qualified and flies on board of the solar orbiter ESA mission launched in 2020.