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 $\tau$ 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.

This work presents the implementation and the preliminary tests of the Multi-channel Integrated Zone-sampling Analogue-memory based Readout (MIZAR) ASIC. Developed using commercial 65 nm CMOS technology, the MIZAR ASIC is designed as part of the Cherenkov camera for the POEMMA Balloon with Radio (PBR) mission. The goal of the Cherenkov camera is to detect direct Cherenkov signals produced by Extensive Air Showers (EASs) pointing towards the detector. The broader objective of the PBR mission is the detection of Ultra-High Energy Cosmic Rays (UHECRs) and tau-induced air showers resulting from the interaction of Cosmic Neutrinos with the Earth's crust. In the MIZAR ASIC, a single channel is segmented into 256 acquisition cells and each one includes a capacitor, a Wilkinson Analog-to-Digital Converter (ADC) and a digital memory. This full waveform sampling system operates with an integration time of 5 ns and the data are converted on chip at the same frequency. MIZAR is designed to send out a 64-bit hitmap to use as first-level trigger to recognize patterns of interest. Each channel can be programmed to reduce the sampling window to 32 or 64 cells and the resolution can be set within the interval 8–12 bits. MIZAR was delivered in March 2025 and it has undergone laboratory testing in recent months.