A 94-GHz Extremely Thin Metasurface-Based BiCMOS On-Chip Antenna

A novel fully on-chip antenna based on a metasurface fabricated in a 180-nm BiCMOS process is presented. Inspired by the concept of high impedance surface (HIS), this metasurface is not used as a reflector below an antenna as commonly done. Instead, it is used as a radiator by itself. The extremely thin metasurface is composed of a patterned top two metal layers and the ground plane placed in the lowest metal layer in the process. The ground plane on the lowest metal layer of the process provides a solid shielding from the substrate and other possible circuitries. The fundamental of the antenna radiation and design are described. The measured antenna shows -2.5 dBi peak broadside gain with 8-GHz 3-dB gain bandwidth and an impedance bandwidth larger than 10 GHz. In its class of broadside radiating fully on-chip antennas, with a ground plane on the lower metal layer of the process, and without additional fabrication processing, this structure achieves the widest impedance bandwidth at W-band and one of the highest gain and gain bandwidth. It is noteworthy that this is achieved with an extremely thin antenna substrate thickness and a shielding ground plane.