Multi-Correlated Double Sampling vs. analog shaper: Low power ASIC for pixelated CdTe

Comparison of continuous time and discrete time noise filtering is presented. Two sets of measurements have been performed: one with the classical analog semi-Gaussian shaper (CR-RC²), the other with M-CDS (Multi-Correlated Double Sampling). The Charge Sensitive Amplifier used in the measurements is optimized for input capacitance of 1 pF and detector dark current below 5 pA. With the analog shaper the Equivalent Noise Charge is characterized as a function of peaking time. ENC in the M-CDS method is characterized against the sampling frequency and the number of samples. The two methods have been compared. They show very similar noise performances: in each case the ENC as low as 30 electrons rms was achieved with the input capacitance of 0.3 pF and CSA power consumption of 14 μW. Spectroscopy measurements with the CSA connected to Si diode were performed using the ⁵⁷CO source. The achieved FWHM resolutions were 390 eV at 14 keY with the analog shaper and 440 eV at 14 keY with the M-CDS method.