A 482-GHz 2-D Scalable and Wideband Radiator Array

This letter reports a 2-D scalable coupled harmonic oscillator array achieving coherent spatial power combining at about 500 GHz. This design is implemented using on-chip microstrip lines and microstrip antennas by which the lossy silicon substrate is shielded and, therefore, front side radiation could be obtained. Compared with previously reported scalable array designs, this work not only achieves maximum oscillation at the fundamental frequency, but also decouples the design of oscillator core, radiation element, and coupling structure. Therefore, different parts could be separately optimized to achieve maximum radiated second harmonic power and more design diversity is possible for the antenna part. To demonstrate the design concept, a 2 x 2 coupled oscillator array is designed and fabricated using 65-nm CMOS process, which achieves a maximum effective isotropic radiated power (EIRP) of 2.6 dBm and radiated power of 162.2 mu W (-7.9 dBm) at 482 GHz. It consumes 154-mW dc power and the dc-to-terahertz (THz) efficiency is 0.11%. This design achieves a 6.8% tuning range from 469 to 502 GHz by changing the bias voltages.