SIRIO: A High-Speed CMOS Charge-Sensitive Amplifier for High-Energy-Resolution X-γ Ray Spectroscopy with Semiconductor Detectors

A fully integrated pulsed reset charge-sensitive amplifier (CSA) optimized for low-capacitance (< 100 fF) radiation detectors was developed on a 0.35- mu ext{m} low-noise CMOS technology. The CSA was successfully tested with a collimated 10-mm2 silicon drift detector (SDD) and extensively characterized. The experimental setup and the achieved spectrometry results with SDD are described for triangular and trapezoidal shaping filters with peaking times ranging from {t_{mathrm {peak}}=0.1!-!12.8,,mu ext {s}} at an operating temperature of -35 °C. With a minimum equivalent noise charge (ENC) of 3.4 electrons rms measured at t_{mathrm {peak}} = 5.6,,mu ext{s} with the SDD connected, corresponding to a pulser linewidth of 29.9 eV full-width at half-maximum (FWHM), the presented results are among the best recorded for integrated CSA designs. The measured ENC at t_{mathrm {peak}} = 0.1,,mu ext{s} is of 8.1 e- rms (70.7 eV FWHM) corresponding to 138.4 eV FWHM on the 5.9 keV 55Fe line. The open-input rise time is below 10 ns and the pulsed reset speed of 4 keV/ns allows a full recovery from a saturated output voltage in 63 ns. These latter results, together with the low-noise performance at short peaking times, make this preamplifier best suited for high-count rate spectroscopy applications that require a research-grade performance, such as in instrumentation for X and gamma spectroscopy and imaging for synchrotron radiation facilities, as well as other scientific or industrial applications.