A readout channel for applications to X-ray diffraction imaging at free electron lasers has been developed in a 65 nm CMOS technology. The analog front-end circuit can achieve an input dynamic range of 100 dB by leveraging a novel signal compression technique based on the non-linear features of MOS capacitors. Trapezoidal shaping is accomplished through a transconductor and a switched capacitor circuit, performing gated integration and correlated double sampling. A small area, low power 10 bit successive approximation register (SAR) ADC, operated in a time-interleaved fashion, is used for numerical conversion of the amplitude measurement. Operation at 5 MHz of the analog channel including the shaper was demonstrated. Also, the channel was found to be compliant with single 1 keV photon resolution at 1.25 MHz. The ADC provides a signal-to-noise ratio (SNR) of 56 dB, corresponding to an equivalent number of bits (ENOB) of 9 bits, and a differential non linearity DNL<1 LSB at a sampling rate slightly larger than 1.8 MHz.
A 2D imager for X-ray FELs with a 65 nm CMOS readout based on per-pixel signal compression and 10 bit A/D conversion / Ratti, L.; Comotti, D.; Fabris, L.; Grassi, M.; Lodola, L.; Malcovati, P.; Manghisoni, M.; Re, V.; Traversi, G.; Vacchi, C.; Rizzo, G.; Batignani, G.; Bettarini, S.; Casarosa, G.; Forti, F.; Giorgi, M.; Morsani, F.; Paladino, A.; Paoloni, E.; Pancheri, L.; Dalla Betta, G. F.; Mendicino, R.; Verzellesi, Giovanni; Xu, H.; Benkechkache, M. A.. - In: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH. SECTION A, ACCELERATORS, SPECTROMETERS, DETECTORS AND ASSOCIATED EQUIPMENT. - ISSN 0168-9002. - STAMPA. - 831:(2016), pp. 301-308. [10.1016/j.nima.2016.05.055]