A mm-Wave Signal Generation and Background Phase Alignment Technique for Scalable Arrays

This work presents a mm-wave signal generation method that provides background phase tuning and self-alignment between adjacent sources. This technique is based on direct monitoring of the mm-wave signal and provides phase tuning through a baseband feedback loop. We present the theory of the concept, provide the design methodology, and validate the proposed method with a two-element prototype in a 65-nm CMOS process. The prototype has a chip area of 1.3 mm × 2 mm and consumes a total dc power of 258 mW. Chip measurements demonstrate a phase tuning range of 140° at 35 GHz with 20°/step and 3.5° of rms phase error. The measured phase switching time is 20 ns. The measured phase noise at 1-MHz offset is below-117 dBc/Hz across phase settings, and the accumulated jitter is 86 fs. These results are consistent with theory and simulation. This work provides a phase alignment technique for large-scale mm-wave phased arrays.