ALTAIR: A Low Noise, Low Power and Wide Dynamic Range ASIC for X and γ Ray Applications with CdTe/CdZnTe Pixel Detectors

We present ALTAIR, an Application Specific Integrated Circuit (ASIC) designed for the readout of CdTe/CdZnTe detectors for X-gamma ray spectroscopic imaging. ALTAIR is composed of 16 channels each with analog and mixed signal sections and it is developed for high energy resolution, high rate applications with the constraint of low power consumption. The ASIC has three selectable input charge signal ranges covering the photon energy from few keV up to 300 keV. The power consumption is about 1.2 mW/ch. A minimum Equivalent Noise Charge of 40 electrons r.m.s (425 eV FWHM in CdTe) has been measured at 500 ns peaking time. With a CdTe pixel detector connected to ALTAIR, a pulser FWHM of 1.7 keV (160 el. r.m.s.) has been achieved at +24°C, mainly determined by the detector leakage current noise and by the stray capacitance due to the connection.