A 0.45-THz 2-D Scalable Radiator Array With 28.2-dBm EIRP Using an Elliptical Teflon Lens

This article presents a novel coherent, scalable radiator array achieving the highest effective isotropic radiated power (EIRP) and highest dc-to-terahertz (THz) efficiency among silicon-based scalable THz sources beyond 400 GHz through co-design and optimization methods of the THz power generation and radiation. First, a 4 $\times $ 4 slot antenna array with silicon substrate loading is optimized for high radiation efficiency and good radiation pattern without silicon lens. A low-cost Teflon lens is introduced and effectively illuminated by the radiator achieving a highly directive beam. Second, a novel 2-D scalable coupled harmonic oscillator array is proposed as the excitation network to feed the antenna array. The oscillator is optimized for the second-harmonic generation to provide high output power and efficiency. The chip is fabricated in a 65-nm CMOS process, and the core area of the chip is 0.55 mm². The radiated power of −2.4 dBm and 8.8-dBm EIRP are achieved at 449.8 GHz with 373-mW dc power consumption and 0.16% dc-to-THz efficiency under 1.2-V supply voltage. By adding an elliptical Teflon lens, 28.2-dBm EIRP is measured at 452.3 GHz under 1.2-V supply voltage, and a maximum EIRP of 29.1 dBm is measured at 458.3 GHz with 1.4-V supply voltage. By changing the bias and supply voltages, a 4.6% frequency tuning range is achieved. At 452.3 GHz, the measured phase noise is −76.4 dBc/Hz at 1-MHz offset.