The entire CMS silicon Tracker will be replaced at HL-LHC with a new detector featuring increased radiation hardness and capability to handle higher data rate and longer trigger latency. The Inner Tracker (pixel detector) will be exposed to the most extreme conditions, requiring advanced technologies and novel solutions notably for the readout and powering electronics, as well as all support structures. The talk introduces the design of the CMS pixel system for the HL-LHC with focus on the novelties. The CMS pixel detector will use a new readout chip in a 65nm feature size technology. Two chips are being developed by the RD53 collaboration for the ATLAS and CMS pixel detector upgrades. During the last year a large variety of test results have been achieved on different sensors connected to RD53A. The talk will summarise the results with focus on the system powering, the radiation hardness and the hit processing efficiency in the extremely high hit-rate environment. Developments of hybrid pixel modules using the readout chips in 65nm technology have started. The talk will introduce the challenges of the module component design and present first results from operation of RD53A quad-chip module prototypes.