An integrated subharmonic coupled-oscillator scheme for a 60-GHz phased-array transmitter

This paper describes the design of an integrated coupled-oscillator array in SiGe for millimeter-wave applications. The design focuses on a scalable radio architecture where multiple dies are tiled to form larger arrays. A 2 x 2 oscillator array for a 60-GHz transmitter is fabricated with integrated power amplifiers and on-chip antennas. To lock between multiple dies, an injection-locking scheme appropriate for wire-bond interconnects is described. The 2 x 2 array demonstrates a 200-MHz locking range and 1 x 4 array formed by two adjacent chips has a 60-MHz locking range. The phase noise of the coupled oscillators is below -100 dBc/Hz at a 1-MHz offset when locked to an external reference. To the best of the authors' knowledge, this is the highest frequency demonstration of coupled oscillators fabricated in a conventional silicon integrated-circuit process.