A 12.5-Gb/s Fresnel Zone Coupled Fully Rotatable 60-GHz Contactless Connector in 65-nm CMOS Process

This work presents a 60-GHz contactless connector that can fully rotate without physical contact. Conventional connectors suffer poor mechanical reliability, maneuverability, and signal integrity when handling moving or rotating parts, such as in robotic arms, often becoming bottlenecks in high-precision autonomous systems. Our implemented system consists of a 60-GHz CMOS transmitter (Tx), receiver (Rx), and compact antenna to enable fully rotatable and energy-efficient contactless connector solutions. Two folded-dipole antennas communicate in a radiative Fresnel zone, where both longitudinal and transversal electromagnetic fields propagate simultaneously. We exploit the longitudinal electric field component to de-sensitize the polarization mismatch over the entire rotational angle. In addition, we employ an automatic gain control (AGC) loop and offset canceling amplifiers to compensate for the transmission characteristic degradation and signal imbalance when connectors rotate. The demonstrated system consumes 56 mW of power under a 1-V supply while transferring 12.5-Gb/s of data rate, achieving 4.5-pJ/bit energy efficiency.