Experimental results of the pFREYA16 ASIC for x-ray ptychography in continuous wave light sources

The pFREYA16, prototype Fast Readout for ptYchography Applications with 16 channels, ASIC is a pixellated 8-by-2 readout matrix developed for ptychography experiments based on fourth generation storage ring light sources, also known as diffraction-limited storage rings (DLSR), pushing towards continuous wave operation. The target of the experiment is to obtain a 128-by-128 matrix of pixels, working at a frame rate of 1 MHz with single-photon resolution, as well as low-noise and low-power figures, in a modest-size pixel area of 150 μm × 150 μm. The readout chain is composed of a switch-reset CSA and a semi-Gaussian unipolar RC-CR shaper, and includes signal discrimination, zero-suppression capabilities, and pixel-level analog to digital conversion. The ASIC is also configurable for 5, 9, 18, or 25 keV input photon energy, with a full well capacity of 256 equivalent photons in each mode, and four different peaking times are available for noise optimisation. The paper will focus on the characterisation of the CSA and the shaper stage.