Inter-Modulated Regenerative CMOS Receivers Operating at 349 and 495 GHz for THz Imaging Applications

This paper introduces an ultra-high frequency inter-modulated regenerative receiver (IRR) that operates beyond the maximum oscillation frequency (f_max) of active devices for terahertz imaging applications. It is accomplished by inter-modulating the fundamental oscillator in a conventional super regenerative receiver (SRR) with a second oscillator to boost the reception frequency. When implemented in 65 nm CMOS technology (f_max = 280 GHz), a maximum reception frequency of 349 GHz is achieved. While in 40 nm CMOS technology (f_max = 350 GHz), the maximum reception frequency increases to 495 GHz. Multiple received bands are also generated at the alternate inter-modulation frequencies, and enable the possibility of false color THz imaging. The prototype IRR consumes 18.2 mW/pixel and occupies 0.021 mm² of silicon area when implemented in 65 nm CMOS technology; and occupies 0.11 mm² while consuming 5.6 mW when implemented in 40 nm CMOS technology.