340-GHz Low-Cost and High-Gain On-Chip Higher Order Mode Dielectric Resonator Antenna for THz Applications

A low-cost and high-gain on-chip terahertz (THz) dielectric resonator antenna (DRA) is proposed in this work. The DRA consists of a low-loss dielectric resonator (DR) made of high-resistivity silicon material and an on-chip feeding patch realized in a 0.18-μm CMOS technology for exciting the desired electromagnetic (EM) mode. The DR can be easily fabricated to the required dimension by wafer dicing of a 2-in silicon wafer. With a 500-μm thick DR, a higher order mode of TE δ, 1 , 7 can be excited, which greatly enhances the antenna gain. Such higher order mode operation also provides a reliable design. If a fundamental mode is selected, the DR thickness is around 100 μm at THz frequencies, which not only requires an additional wafer thinning process, but the wafer is also easily broken during the fabrication process. The feeding patch is used to excite the TE δ, 1 , 7 mode. Moreover, its ground plane also prevents the EM field from leaking into the lossy CMOS silicon substrate, which improves the antenna efficiency. The simulated antenna gain can be 7.9 dBi while providing radiation efficiency of 74% at 341 GHz with 7.3% bandwidth. To characterize the DRA performance, an identical CMOS imager is designed to be integrated with the proposed DRA and an on-chip patch antenna. By comparing the measured responsivity of these two imagers, the gain improvement of the DRA over the on-chip patch antenna can be obtained. Three samples are measured to evaluate the robustness of the proposed antenna over process variation. The measured results show that the maximum gain improvement of 6.7 dB can be acquired at 327 GHz. The proposed DRA with the integrated CMOS imager is also employed to successfully demonstrate a THz transmissive imaging system at 327 GHz. To the best of authors’ knowledge, this is first higher order mode DRA working at THz frequencies.