Filling the terahertz gap with sand: High-power terahertz radiators in silicon

This paper reviews our recent work on Si and SiGe THz sources that generate high-power coherent radiation. Our design approach blends the optimization of device operation near or above f_max with unconventional circuit topologies and energy-efficient electromagnetic structures. Using a 130-nm SiGe HBT process (f_max=3D280 GHz), our 320-GHz transmitter produces a record radiated power (3.3 mW) and DC-to-THz radiation efficiency (0.54%) among all THz signal sources in silicon. This transmitter also demonstrates fully-integrated phase-locking capability for THz radiators for the first time. In this paper, a 260-GHz pulse radiator and a 340-GHz phased array, which are based on a 65-nm bulk CMOS process, are also presented. The former generates a radiated power of 1.1 mW, and provides THz pulses with 25-GHz bandwidth. The latter generates a radiated power of 0.8 mW and has a 50^° beam-steering capability. These works demonstrate a promising roadmap towards future THz microsystems using silicon integrated-circuit technologies.