A Gain Levelling Technique for On-Chip Antennas Based on Split-Ring Resonators

This paper introduces a gain enhancement technique for monolithically integrated antennas. Such devices can suffer from gain dips within their operating bandwidth due to standing waves arising in the die or caused by interactions with other on-chip components. In this work, it is shown how these effects can be significantly mitigated by parasitically coupling square Split Ring Resonators (SRR) to the fed antenna. The SRRs geometry and their coupling with the master antenna can be set in such a way that they create an additional resonance that cancels gain drops and improves impedance matching. The proposed configuration has been validated using a W-band monopole antenna in a standard 0.13 μm SiGe BiCMOS process. Thanks to the proposed approach, it was possible to compensate a gain drop of about 7 dB at about 85 GHz. As a result, the experimental assessment showed a maximum measured antenna gain of 1.61 dB at 81.5 GHz and an operating bandwidth from 77 to 87 GHz.