A silicon photomultiplier readout ASIC for the Mu3e experiment

The Mu3e experiment is a proposed experiment to probe for new physics by searching for the charged lepton-flavour violating decay μ⁺→e⁺e⁺e^- with a branching ratio sensitivity of 10^-16, improving the current limit by four orders of magnitude. To search for such rare events, extremely high muon decay rate, good background suppression and high detector efficiencies are required. This demands an excellent momentum, vertex and timing resolution from the detector systems. Furthermore, the experiment will be running at a muon stopping rate of more than 10⁹ Hz in order to observe enough muon decays in a reasonable experiment running time. This poses another challenge to the detectors and readout electronics, which have to be designed to cope with the present event rate. This thesis presents the development of a dedicated Silicon Photomultiplier (SiPM) readout Application-Specific Integrated Circuit (ASIC) for the Mu3e timing detectors. It provides the precise timing measurement while being capable of working with the high event rates. Fully differential analog front-end channel and 50 ps time binning TDC are utilized to achieve excellent timing resolution. The customized Low-Voltage Differential Signaling (LVDS) transmitter cell and double data rate serializer provides gigabit data rate to transfer data out of the chip. Detailed measurements have been preformed to characterize the timing performance and to verify the digital functionalities of the chip.