Evaluation of integrated antennas for wireless connection between an integrated circuit and an off-chip antenna

Integrated antennas for wireless connection between an integrated circuit and an off-chip antenna have been evaluated. At 23.5 GHz, the power transmission gain between an integrated 2-mm zigzag dipole antenna and an off-chip antenna increases by 5 dB and 10 dB when the substrate is changed from a 5-Ω-cm to a 20-Ω-cm silicon wafer, and from a 20-Ω-cm silicon wafer to a sapphire substrate, respectively. The antenna pair gain can be 20-30 dB higher than that for a pair of on-chip antennas, which leads to ∼25 dB better sensitivity for a clock receiver working with an external antenna. This work also suggests that the integrated antenna length can be reduced below 1 mm.