  IDeF-X HD is a 32-channel analog front-end with self-triggering capability
optimized for the readout of 16 x 16 pixels CdTe or CdZnTe pixelated detectors
to build low power micro gamma camera. IDeF-X HD has been designed in the
standard AMS CMOS 0.35 microns process technology. Its power consumption is 800
micro watt per channel. The dynamic range of the ASIC can be extended to 1.1
MeV 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 10.7 micro seconds peak time. Spectroscopy
measurements have been performed with CdTe Schottky detectors. We measured an
energy resolution of 4.2 keV FWHM at 667 keV (137-Cs) on a mono-pixel
configuration. Meanwhile, we also measured 562 eV and 666 eV FWHM at 14 keV and
60 keV respectively (241-Am) with a 256 small pixel array and a low detection
threshold of 1.2 keV. 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 110 MeV/(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 the Solar Orbiter ESA mission
launched in 2020.
