Design and Verification of a 6.25 GHz LC-Tank VCO Integrated in 65 nm CMOS Technology Operating up to 1 Grad TID

This article presents the design of an LC-Tank voltage-controlled oscillator (VCO) for space and high-energy physics (HEP) applications. The main goal of this work is to design a radiation-hard oscillator to be integrated into a phase-locked loop (PLL), compliant with (but not limited to) SpaceFibre protocol requirements, which is able to support the 6.25 GHz frequency. The full custom schematic and layout of the LC-VCO are reported in this work. The LC-VCO is implemented in a commercial 65 nm CMOS technology, and its electrical characterization highlights a tuning range (TR) from 5.4 to 6.8 GHz. An experimental chip was fabricated and irradiated with X-rays up to 1 Grad (SiO2) total ionizing dose (TID) level at CERN facility. The TID experiment and measurement results are analyzed and discussed. The LC-VCO shows a frequency degradation of 2.54% and a 3.34% increment in phase noise at 1 Grad TID. The results achieved are of interest for both space and HEP applications.