122 GHz patch antenna designs by using BCB above SiGe BiCMOS wafer process for system-on-chip applications

Two half-wavelength 122 GHz patch antennas were designed and manufactured by using Benzocyclobutene (BCB) as a dielectric layer above the SiGe BiCMOS wafer. It enables the full integration of the millimeter-wave transceiver circuits and the antennas on a single chip to simplify the packaging procedure at millimeter-wave frequencies, thereby reducing the cost. The two patch antennas are fed by different feeding methods, i.e. microstrip transmission line direct feed and proximity-coupled feed. They exhibit similar performance and offer the flexibility of designing the interconnects (feed lines routing) between the circuits and the antennas within the very limited chip area. The measured gain is 3.4 dBi at 122.5 GHz (the center frequency of the ISM band of 122–123 GHz) for both designs with a simulated efficiency of about 50%.