A 0.68–0.72-THz 2-D Scalable Radiator Array With –3-dBm Radiated Power and 27.3-dBm EIRP in 65-nm CMOS

A novel and compact 2-D scalable architecture of coupled harmonic oscillator array is proposed for high-power radiation beyond 600 GHz. The compact and symmetric scalable unit cell comprises two oscillators with two slot antennas radiating the third-harmonic power. Each unit cell is horizontally coupled out-of-phase and vertically in-phase with adjacent cells at the fundamental frequency. Therefore, coherent radiation and power combining are achieved at the third harmonic. A $4\times4$ array prototype (32 radiating elements) is designed and fabricated in a 65-nm CMOS technology. An elliptical Teflon lens is attached at the backside of the chip for a highly directive beam. An effective isotropic radiated power (EIRP) of 27.3 dBm and an output power of −3 dBm are measured at 694-GHz with 754-mW power consumption under 1.2-V supply voltage, implying a dc-to-terahertz (THz) efficiency of 0.066%. The core design occupies a chip area of 0.61 mm², and the entire chip area is 0.97 mm², leading to a 0.52-mW/mm² area efficiency. The peak EIRP of 27.8 dBm and the radiated power of −2.4 dBm are measured at 699 GHz under 1.3-V supply voltage. A frequency tuning range of 5.26% from 679.4 to 716.1 GHz is measured by varying bias and supply voltages. The measured phase noise at 1-MHz offset is −73 dBc/Hz at 694 GHz. To the best of our knowledge, the designed array has the highest radiated power, radiated power per area, EIRP, frequency tuning range, and dc-to-THz efficiency among silicon-based scalable coherent radiator arrays operating beyond 600 GHz.