A 28 GHz Optically Synchronized CMOS Phased Array with an Integrated Photodetector

This paper presents a modular 28 GHz phased array. Each of its
$\mathrm{2}\times \mathrm{4}$
-modules is driven by a CMOS RFIC, whose RF output is optically synchronized using a fully integrated silicon photodiode. The photocurrent is amplified using a tuned injection-locked TIA to serve as the reference for an on-chip synthesizer, which generates and distributes the RF signal to the PAs that drive the antennas. We demonstrate beam steering, data transmission, and synchronization of array modules up to 25m away from the clock source.