A Front-End Circuit in 28 nm CMOS for Hydrogenated Amorphous Silicon Detectors in Clinical Dosimetry

Giovanni Mazza, Lorenzo Piccolo, Luca Antognini, Saba Aziz, Aishah Bashiri, Lucio Calcagnile, Daniela Calvo, Domenico Caputo, Anna Paola Caricato, Roberto Catalano, Roberto Cirio, Giuseppe Antonio Pablo Cirrone, Tommaso Croci, Giacomo Cuttone, Gianpiero De Cesare, Paolo De Remigis, Sylvain Dunand, Michele Fabi, Luca Frontini, Catia Grimani et al. (33 additional authors not shown)

Abstract: This paper presents the design and the charac-terization of a front-end circuit, designed in 28 nm CMOS, for real-time dosimetry in radiation diagnostics and radiation therapy. The front-end circuit is optimized for sensors made of hydrogenated amorphous silicon. The scheme is based on a current- to- frequency converter to sustain a large range of input currents. Three different programmable solutions have been investigated to be compatible with a wide variety of sensor sizes and applications. The front-end has been designed around three key specifications: an input capacitance between 1 pF and 50 pF, an input current from 100 pA to 2 µA, and a measurement time ranging from 400 µs to 60 ns. A first prototype has been fabricated and it is being characterized in laboratory.