64-channel ASTEROID ASIC: Experimental performance and measurements with Macro Pixel arrays for X-ray astronomy

The 64 channel ASTEROID ASIC has been designed to readout DEPFET pixel matrices for astronomy. In particular ASTEROID will be the readout ASIC of the DEPFET based Macro Pixel X-ray detector for the MIXS instrument on the European Mercury exploration mission BepiColombo. For this mission a detector system with high speed readout, high energy resolution and radiation hardness properties is required. Each of the 64 analog channels implements a trapezoidal weighting function. This is the optimum time limited filter for the white series noise, which is dominant at the foreseen readout speed. The ASIC is implemented in the 0.35 ¿m 3.3 V AMS CMOS technology. The spectroscopic performance of ASTEROID coupled with a 64×64 Macro Pixel array prototype with pixel area of 500×500 ¿m² has been tested. An energy resolution of 128.5 eV FWHM with the reconstruction of all split events has been measured on the Mn-ka of a ⁵⁵Fe source operating ASTEROID with a total readout time of 4.8 ¿s at -80°C. Furthermore radiation hardness measurement on the digital section of the ASIC, both with a 10 MeV proton source and with a 5.5 MeV a particles source, proved the SEU immunity of the DICE based SRAM cells.