A 100-GHz CMOS-Compatible RIS-on-Chip Based on Phase-Delay Lines for 6G Applications

TL;DR

This paper introduces a CMOS-compatible on-chip reconfigurable intelligent surface (RIS) with beam steering capabilities for 6G, utilizing phase-delay lines and VO2 to achieve high reflection control and low loss.

Contribution

It presents the first on-chip RIS design capable of beam steering using phase-delay lines and VO2, demonstrating practical fabrication and significant reflection modulation.

Findings

Achieved 180° phase difference at center frequency with VO2 states

Demonstrated 27.1 dB reflection enhancement between ON and OFF states

Fabricated a 60x60 RIS array with beam-steering capability

Abstract

On-chip reconfigurable intelligent surfaces (RIS) are expected to play a vital role in future 6G communication systems. This work proposed a CMOS-compatible on-chip RIS capable of achieving beam steering for the first time. The proposed unit cell design is a combination of a slot, a phase-delay line with VO2, and a ground. Under the two states of the VO2, the unit cell has a 180 deg phase difference at the center frequency, while maintaining reflection magnitudes better than -1.2 dB. Moreover, a 60by60 RIS array based on the present novel unit is designed, demonstrating the beam-steering capability. Finally, to validate the design concept, a prototype is fabricated, and the detailed fabrication process is presented. The measurement result demonstrates a 27.1 dB enhancement between ON and OFF states. The proposed RIS has the advantages of low loss, CMOS-compatibility, providing a foundation for future 6G applications.