  The phase-2 upgrade of the LHC will require novel pixel readout chips, which
deliver hit information at drastically increased data rates and tolerate
unprecedented radiation levels. The large-scale prototype chip RD53A has been
designed by the RD53 collaboration and manufactured in a 65 nm CMOS process,
suitable for the innermost layers of both the ATLAS and the CMS experiment. In
order to verify the radiation hardness design goal of 500 Mrad total ionizing
dose, RD53A has been irradiated using X-rays. The radiation effects on the
performance of the data link, reset circuit and the clock generation have been
investigated. Furthermore, the operating margins in terms of supply voltage and
frequency have been analyzed.
