GAMMA: A 16-Channel Spectroscopic ASIC for SiPMs Readout With 84-dB Dynamic Range

• Published in: IEEE transactions on nuclear science Vol. 68; no. 10; pp. 2559 - 2572
• Main Authors: Buonanno, Luca, Vita, Davide Di, Carminati, Marco, Fiorini, Carlo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acidity; Amplitude modulation; Application specific integrated circuits; Circuit design; Crystals; Detectors; Direct reduction; Dynamic range; Energy resolution; Gain control; Gated-integrator; Integrated circuits; Lanthanum; lanthanum bromide; Photomultiplier tubes; Photonics; scintillators; Signal processing; Signal to noise ratio; silicon photomultipliers (SiPMs); SiPMs integrated readout circuits; Sodium channels; Spectroscopy
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2021.3107333

Gain amplitude modulation multichannel ASIC (GAMMA) is a 16-channel application specified integrated circuit (ASIC), designed in 0.35-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> technology to read the charge provided by silicon photomultipliers (SiPMs) on a wide amplitude range. This chip was designed to satisfy the demanding requirements of the INFN the GAMMA project, where a 3" <inline-formula> <tex-math notation="LaTeX">\times3 </tex-math></inline-formula>" large lanthanum bromide crystal is to be read by SiPMs, aiming at state-of-the-art energy resolution. Because the energy range of the application is 100 keV-20 MeV, signals in a wide dynamic range (DR) have to be processed by the ASIC. This wide DR requirement raised the necessity of an adaptive gain change solution in order to guarantee a high signal-to-noise ratio together with a large full-scale range. While the ASIC input stage features a programmable static gain, the analog filtering channel exploits a self-triggered gated integrator stage with an automatically adjusted gain for each detected input current pulse; one of the following values is selected: 10, 2, or 0.83 [mV/pC]. The gated integrator gain is predictively adjusted before the circuit reaches saturation due to a time-gated threshold mechanism and provides negligible charge loss when the gain is switched (< 20 fC). A preintegration feature is also implemented in order to get rid of nonlinearity due to delays in the integration phase that could take place in a multi-ASIC system. The ASIC uses 5- and 3.3-V bias voltages, the overall power consumption being 280 mW. The ASIC was tested with a <inline-formula> <tex-math notation="LaTeX">12\times12 </tex-math></inline-formula> SiPMs matrix coupled with a 3 inch LaBr 3 , providing good spectroscopic performances (2.6% at the 137 Cs photopeak emission energy of 662 keV), and was also tested irradiating the SiPMs with fast, bright NUV light pulses, in order to explore the ASIC wide range coverage while simulating the scintillation light emission of a lanthanum bromide crystal.