VMM3a: an ASIC for Tracking Detectors

The VMM3a is a custom Application-Specific Integrated Circuit (ASIC). It will be used as the front-end ASIC for both Micromegas and sTGC detectors of the ATLAS Muon New Small Wheel upgrade at CERN. Due to its flexibility and several configurable parameters, it has also been proposed to a variety of tracking detectors in other experiments. The ASIC integrates $64$ independent channels, each providing amplitude and timing measurements, in digital or analog format. The chip has undergone three major revisions and a minor one, with the first prototype being produced in $2012$. It began as a purely analog chip, providing timing and amplitude measurements for digitization by external ADCs, while its latest version combines analog circuitry, internal ADCs, digital buffers and logic that produces fast signals for triggering, all in one chip. In this document, the design aspects of the VMM3a as a production ASIC will be presented.