Phase Locked Loop Design for Distributed Phased Array Transceivers

Modern millimeter wave transceivers require hundreds of individual antenna elements where each element needs to be able to have a unique phase shift from the reference signal. We propose an architecture where each antenna element is driven by a unique front end that derives the local oscillator signal using a phase controllable phase-locked-loop (PLL) synchronized by a relatively low frequency signal. This architecture is scalable from a handset or vehicle based phased array consisting of only a few antennas to 5G cellular base stations and satellite communications.

RF and millimeter wave transceivers require ever improving frequency accuracy to enable higher and higher data rates. Improvements in VCO design and new PLL architectures allow for reaching even better figures of merit in designs. This work examines the class-F oscillator and its applications within RF and millimeter wave transceivers. A new topology for a class-F oscillator is also introduced. These high performance oscillators are then used as part of an all-digital fractional-N phase controllable PLL. The reliability concerns regarding oscillator design are also examined alongside applications for reliability study to identifying recycled devices.

The proposed PLL allows for working towards a fully software defined phased array, where each element can be individually controlled and transmit unique waveforms or the entire array can work together for enhanced beam forming capabilities. This approach allows for new reconfigurable and scalable RF and MMW systems, and it will enable new approaches to phased array applications.