The Italian research program CHIPIX65, funded by INFN, and the international RD53 collaboration, both aimed at the development of the pixel readout chip for the phase-2 upgrades of the CMS (a Compact Muon Solenoid) and ATLAS (A Toroidal LHC ApparatuS) experiments at the LHC in Geneva, Switzerland. While the CHIPIX65 collaboration completed its campaign in 2018, RD53 activity is in full swing, with tests running on the most recent multichannel chip prototypes. The group at EIL contributed in particular to the design and characterization of the front-end channel for the upgraded version of the CMS hybrid-pixel detector. The circuit design, carried out in a 65 nm CMOS technology, has to comply with extremely tight specifications in terms of power dissipation (<5 uW reserved for the analog section), area (about half of the overall pixel area, 50 um x 50 um), speed (peaking time smaller than 25 ns) noise occupancy (below 10-6) and radiation hardness (tolerance to a total dose of 500 Mrad(SiO2) is required).
