A 482GHz 2-D Scalable and Wideband Radiator Array

This paper reports a 2-D scalable coupled harmonic oscillator array achieving coherent spatial power combining at about 500GHz. 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 2×2 coupled oscillator array is designed and fabricated using 65-nm CMOS process, which achieves a maximum EIRP of 2.6 dBm and radiated power of 162.2 μW (-7.9dBm) at 482 GHz. It consumes 154-mW dc power and the dc-to-THz efficiency is 0.11%. This design achieves a 6.8% tuning range from 469 GHz to 502 GHz by changing the bias voltages.