A 64-channel ASIC for full waveform sampling with 200 MS/s for space-based cosmic-particles applications

This paper discusses the development of a 64-channel ApplicationSpecific Integrated Circuit designed in a commercial 65 nm CMOS technology to readout a camera plane composed of Silicon Photo-Multipliers. The purpose of the readout chain is the observation of Extensive Air Showers by detecting the Cherenkov radiation which signal is produced by Ultra-High Energy Cosmic Rays and Cosmic Neutrinos. Each ASIC generates a hitmap sent to an FPGA to analyze the pixel proximity. The stored data can be digitally converted on-chip if it is validated through this external checker. A single ASIC is formed by channels where 256 cells are connected to the output of the front-end electronics to obtain a full waveform sampling. An analog memory, a 12-bits Wilkinson Analog-to-Digital Converter and latches are placed into the cell unit working at 200 MHz clock. To derandomize the input signal, the array of cells is partitioned into segments of 32 cells each. The readout is realized using a serializer operating at 400 MHz in Double Data Rate. The ASIC is developed in the framework of the Extreme Universe Space Observatory - Super Pressure Balloon 2 mission, but it is also suitable for several other applications due to its configurability such as the partitioning and the resolution in the range of 8-12 bits. In this way, the chip can save power and conversion time, depending on the requirements of the experiment.