Development and Characterisation of a Radiation Hard Readout Chip for the LHCb Outer Tracker Detector
The reconstruction of charged particle tracks in the Outer Tracker detector of the LHCb experiment requires to measure the drift times of the straw tubes. A Time to Digital Converter (TDC) chip has been developed for this task. The chip integrates into the LHCb data acquisition schema and fulfils the requirements of the detector.The OTIS chip is manufactured in a commercial 0.25µm CMOS process. A 32-channel TDC core drives the drift time measurement (25ns measurement range, 390ps nominal resolution) without introducing dead times. The resulting drift times are buffered until a trigger decision arrives after the fixed latency of 4µs. In case of a trigger accept signal, the digital control core processes and transmits the corresponding data to the following data acquisition stage. Drift time measurement and data processing are independent from the detector occupancy. The digital control core of the OTIS chip has been developed within this doctoral thesis. It has been integrated into the TDC chip together with other constituents of the chip. Several test chips and prototype versions of the TDC chip have been characterised. The present version of the chip OTIS1.2 fulfils all requirements and is ready for mass production.
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