Electronics Design and Layout Complexity of the ATLAS New Small Wheels

The LHC resumes its operation in 2015 aiming to deliver an average luminosity of 1×10^34 cm^−2 s^−1. Further upgrades of the experiments and the accelerator in 2018/19 and 2022/23 will allow to further increase the luminosity to 2×10^34 cm^−2s^−1 and 5×10^34 cm^−2s^−1, respectively. For the ultimate HL-LHC phase the expected mean number of interactions per bunch crossing will increase from 55 at 2×10^34 cm^−2s^−1 to ∼140 at 5×10^34 cm^−2s^−1. This increase, drastically impacts the ATLAS trigger rates. For the ATLAS Muon Spectrometer, a replacement of the innermost endcap stations, the so called “Small Wheels”, is therefore planned for 2018/19 to be able to maintain a low pT threshold for single muon and excellent tracking capability also in the HL-LHC regime. The New Small Wheels will feature two new detector technologies, Resistive Micromegas and small strip Thin Gap Chambers conforming a system of ~2.4 million readout channels. Both detector technologies will provide trigger and tracking primitives to the muon trigger system and are already designed as fully compliant with the post-2024 HL-LHC operation. The electronics design of such a system will be implemented including the design of 4 custom front-end ASICs capable to drive trigger and tracking primitives. Among them the 64 channels VMM, a common frontend ASIC providing amplitude, timing measurements, per channel analog-to-digital conversions and in parallel direct trigger outputs. The design integrates the Gigabit transceiver and Slow Control ASICs developed at CERN. The data flow is designed through a high-throughput network. The overall design along with the first ASIC and board prototypes will be presented.