Timing performance of a monolithic CMOS pixel detector front-end in 180nm technology

The Monopix chips are a series of depleted monolithic active pixel sensors (DMAPS) for high-energy particle physics experiments with fast readout and high radiation tolerance. TJ-Monopix2 is the latest device fabricated in 180nm Tower Semiconductor imaging technology. Monopix chips make use of commercial CMOS processes offering high-resistivity silicon with high-voltage capabilities to ensure depletion of the sensitive volume. The monolithic design combines the sensor component, where the charge signal is produced, and the readout electronics on the same wafer. This approach reduces the material budget of the detector as well as the assembly steps compared to hybrid pixel detectors. The development line targets ATLAS ITk outer pixel layer requirements, expecting a NIEL fluence of up to 1×10 15 n eq cm −2 and 1MGy total ionizing dose. The pixel matrix is capable of handling hit rates of up to 100MHzcm −2 while providing precise timestamping within 25ns. Tracking detectors in high-rate environments require a high time resolution to extend the track separation capabilities beyond spatial dimensions. This paper presents the timing performance of TJMonopix2 measured in the laboratory and in particle beams. A focus is put on the time resolution of the analog front-end and in combination with the sensor part.