Performance at Cryogenic Temperatures of an Ultra Low Noise CMOS Front-end for Fano-limited X-ray Spectroscopy

We qualified the noise performance of Sirio CMOS Charge Sensitive Preamplifier as a function of temperature down to -92 °C. The goal is twofold: i) quantify the improvement of the ENC and ii) disentangle the temperature dependence of the individual noise contributions and identify critical design issues. The intrinsic noise of the preamplifier, without connection to any detector, has been measured by injecting charge pulses through a test capacitance. The main noise contributions (series white, series flicker, parallel white) have been extracted from the experimental data. The lowest measured ENC at the optimal peaking time is around 1 el. rms.