Millimeter-wave spoof plasmonic phase shifter with customizable phase resolution

Programmable phase shifters (PSs) are essential components in 5G/6G communication systems, radar transceivers, and planar diffractive neural networks. However, conventional PS designs are often limited by phase resolution, power consumption, complex peripheral circuits, or bandwidth. Here, we propose a programmable phase shifter chip fabricated in 65-nm CMOS technology, enabled by spoof surface plasmon polariton (SSPP) structures. The architecture integrates an analog SSPP PS with a continuous 90° tuning range, along with two 1-bit digital PSs offering discrete phase states of 0°/90° and 0°/180°. By combining the continuous SSPP phase modulation with digital phase states, a full 360° phase coverage is achieved, and the phase resolution can be flexibly customized to match various application requirements. Experimental results demonstrate that the SSPP analog PS enables fine and continuous phase control with low power consumption, whereas the digital PSs extend the overall phase range without degrading resolution. Compared with the conventional PS designs, this approach offers customizable phase resolution, a wide fine-tuning range enabled by the SSPP structure, and reduced power consumption, making it well-suited for emerging millimeter-wave phased arrays and neuromorphic electromagnetic systems.