Personnel

FICs - Prof. Wing-Hung Ki

Description

The Large Hadron Collider (LHC) was built by the European Organization for Nuclear Research (CERN), and is used to study particle physics and high-energy physics. It is popularly recognized by the 27km tunnel in circumference that runs from 50m to 175m underground at the FranceSwitzerland border near Geneva. The primary measurements are proton-proton collisions. Proton beam-bundles are generated and accelerated by superconducting magnets in adjacent but opposite travelling beam-pipes. The protons eventually attain energy of 7TeV, and are then steered to collide in the ATLAS (A Toroidal LHC ApparatuS) detector and the CMS (Compact Muon Solenoid) detector, with a total energy of 14 TeV. The collision debris initiate generation of electron-hole pairs in the encompassing pixel detectors, and the charge is then integrated by the readout front-end electronics, to determine the elapsed time, trajectory, polarity and energy of the debris.

Our research is targeting at the high-luminosity (HL) LHC upgrade of the ATLAS detector in 2023, as the particle luminosity will be increased by 10 times. The pixel detector readout frontend integrated circuits (FE-ICs) will be fabricated in 65nm CMOS process that allows more analog and digital signal-processing circuits to be implemented. The power consumption will thus be increased by 4 to 5 times. The operating power management units (PMUs) will have to retire; and we propose to reduce the input current to the PMUs as well as the weight of the cables by 50%. Lower input current means higher input voltage for the DC-DC buck converter (20V instead of the previous 10V), but for the detector electronics, the supply voltage of the analog and digital circuits remains at 1.2V and 0.9V. Hence, the design challenges are lower voltage conversion ratio and higher switching frequency for handling larger output power, while maintaining or achieving better efficiency. The PMU has to remain functional in an environment with high radiation and high magnetic field. It is also required not to export conducted and radiated electromagnetic interference (EMI) to both the upstream main converters and the downstream detector electronics.

To summarize, we propose to design, fabricate and test the PMUs to be installed in the ATLAS detector. The research works include analysis, design, simulation, layout, tape-out, testing and debugging. Besides functional and performance tests, temperature, radiation and magnetic-field tests will be conducted. Research personnel will be sent to CERN to participate in technical discussions and to identify implementation and installation issues.

Source: RGC | ITF