In the frame of the PixFEL research program, the group at EIL has been working on the development of a readout channel for applications to X-ray diffraction imaging at free electron lasers (FELs). The circuit, designed in a 65 nm CMOS technology, was meant to read out the signal from slim edge pixel sensors with a 100 um pitch, according to a hybrid detector approach. The analog front-end circuit can achieve an input dynamic range of 80 dB by leveraging a novel signal compression technique based on the non-linear features of MOS capacitors.
Trapezoidal shaping is accomplished through a time-variant 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. Currently, the group, in collaboration with researchers at Università di Bergamo and at the Argonne National Laboratory, USA, is working on the design of a front-end channel reading the signals from a pixel detector in view of ptychography applications at synchrotron radiation sources.