Development of ASICs for CdTe pixel and line sensors

We are developing analog ASICs for Cadmium Telluride (CdTe) pixel and line sensors for high energy astrophysics and other applications. In the ASIC development, we are cooperating with other application users to build up a library of "tried-and-true" circuit modules tuned for several processes ("Open IP project"). As an initial trial, a 2-dimensional ASIC with a pixel size of 260 μm × 260 μm and a 1-dimensional ASIC with an improved analog circuit, both based on 0.35-μm CMOS technology, were developed and investigated. The readout system of the pixel ASIC worked properly, but the electric/electronic noise was too large compared with our final goals of 1keV (FWHM). With the latter ASIC, we have preliminarily obtained an energy resolution of 4.9 keV (FWHM) for 59.5 keV gamma-rays combined with a Schottky CdTe diode detector.