Serial powering for ATLAS ITk pixel modules

Even as pixel detector power requirements grow, the space for electrical connections and service cables does not. The ATLAS ITk pixel detector will use a serial powering scheme in which several modules in a serial powering chain are fed on a single power circuit. The voltage drop across each module is the same, but the reference voltage for each module is different. A serial power chain prototype, complete with digital pixel modules using the ITkPixV1 chip, has been tested extensively to demonstrate the performance of serial powering. We report on results from that system test, and we highlight the special electronics design considerations needed for serial powering, from FE chip to services infrastructure and grounding rules.