0.4-THz wideband imaging transmitter in 65-nm CMOS

A wideband THz imaging transmitter in a 65-nm bulk CMOS process is demonstrated. The TX generates 0.73 mW of peak P
out
at 448 GHz and operates over a setup-limited bandwidth of 15% by using an energy efficient frequency quadrupler implemented with a cascade of two frequency doublers, and by co-optimizing the power driver and accumulation-mode symmetric MOS varactor frequency tripler. The TX has the highest reported single-element power density and 0.8% (1.66% w/o PLL) DC to RF conversion efficiency after including PLL and driving amplifier power consumption is the highest reported among CMOS and SiGe HBT sources operating above 0.3 THz.