Measurements and performance of a low noise 64-channel ASIC with CdTe strip detectors

We present the design and measurement results of an ASIC aimed to work with both AC and DC coupled detectors, in a single photon counting mode with an energy window. The ASIC can work with input leakage currents in the range from −10 nA up to 7 nA. The ENC obtained with an AC-coupled Si detector is 120 e − for a peaking time T p = 115 ns and C det = 1.2 pF. With a DC-coupled CdTe detector, the ENC is 160 e − rms for a peaking time T p = 380 ns and C det = 2 pF and the leakage current I dleak = 0.15 nA. The implemented trim DACs at the discriminator inputs allows to minimize the effective threshold spread to 8 e − rms (at one sigma level). We also present the updated version of the ASIC that can operate with X-ray energies up to 100 keV and has an improved high count rate performance. For the new ASIC the preliminary measurements with the CdTe detector are presented.