A readout system for monolithic pixel sensor prototypes towards the upgrade of the ALICE Inner Tracking System

The ALICE experiment at CERN is developing an innovative third iteration of the three innermost layers of the Inner Tracking System (ITS3) to be installed during the Long Shutdown 3 of the LHC (2026-28) [1]. Based on a commercial 65 nm CMOS imaging technology by TowerJazz [2], it consists of truly cylindrical wafer-scale sensors that can be installed as close as 18 mm to the interaction point. In order to validate the technology, several test chips were produced in a first submission named Multi-Layer Reticle 1 (MLR1). This contribution will describe the development, features, and performance of a custom test system for some of the prototypes in MLR1, namely Analogue and Digital Pixel Test Structures (APTS and DPTS, respectively) and pixel matrices with rolling shutter readout (CE65).