A 160×128 single-photon image sensor with on-pixel 55ps 10b time-to-digital converter

In this paper, we present an array of 160x128 pixels capable of detecting the ToA of single photons, implemented in 0.13μm CMOS technology. The sensor is partitioned into 4 identical quadrants that are served by a balanced clock tree so as to minimize skews and to ensure the fastest possible readout process. The pixels in the rows are read out in rolling shutter mode in two directions (top and bottom) simultaneously. The 10b content of each pixel is thus transferred to the exterior of the chip via 320 independent serializers, 2 for each column, working in parallel at a maxi mum rate of 160Mb/s, thus enabling in principle the readout of a complete frame in 4μs. In our implementation the frame rate is actually lower, due to current lim itations in the readout firmware. The region-of-interest (Rol) is programmable, via vertical and horizontal registers that select which rows and columns are read out.