Preliminary Results of the 64-Channel SiPM Readout MIZAR ASIC

This work describes the development of the Multi-channel Integrated Zone-sampling Analogue-memory based Readout (MIZAR) ASIC. This 64-channel chip was designed as part of NASA’s POEMMA Balloon with RADIO (PBR) mission, which aims to detect Ultra-High-Energy Cosmic Rays (UHECRs) and τ showers produced by the interaction of Cosmic Neutrinos (CNs) in the crust. The ASIC was implemented to read out a tile of 8 × 8 Silicon Photomultipliers (SiPMs) used to acquire the optical Cherenkov signals generated by Extensive Air Showers (EASs). A channel is partitioned into 256 cells where each one integrates an analogue memory, a Wilkinson Analog-to-Digital Converter (ADC) and a digital memory operating at the nominal sampling rate of 200 MS/s (with a 5 ns integration time). The signal is digitized on-chip, then the converted data is read out by an FPGA. The MIZAR also provides a 64-bit hitmap as a first-level trigger which can be elaborated by an external firmware. This ASIC can also be configured to further segment the channels into units of 32 or 64 cells each and the ADC resolution can be set to a range between 8 and 12 bits. The chip was designed in a commercial 65 nm CMOS technology node and it was submitted for production in December 2024. The ASICs were delivered in March 2025.