System development and validation for the CMS Inner Tracker at High Luminosity LHC

The CMS Inner Tracker pixel detector will be entirely replaced for the High Luminosity LHC. The development of the readout system for the new detector relies on several system choices each of which requires dedicated studies. The RD53A readout chip was tested and its three analogue front-ends were compared, which allowed to choose the Linear front-end with an improved design for integration into the new CMS readout chip. Two methods to measure cross-talk in pixel sensors were proposed and verified on five sensors to contribute to the choice between square and rectangular pixels. Asymmetric cross-talk of the order of 10% was put in evidence in rectangular pixels and two handles to reduce it were identified: the pixel design and the preamplifier bias. Finally, different prototypes of electrical links were evaluated and compared towards the implementation of the data link ensuring a sufficient signal integrity for a correct reception of the data by the lpGBT chip. The influence of pre-emphasis implemented in RD53A on the signal quality was also studied.