An 820-GHz Down-Converter With Fourth Subharmonic Mixer in 40-nm CMOS Technology

In this letter, an 820-GHz down-converter based on the subharmonic mixer and low noise amplifier (LNA) with low conversion loss and noise figure is proposed. To reduce the frequency of local oscillation (LO) signal, a fourth subharmonic architecture is adopted for the mixer implementation. Meanwhile, to improve the isolation of the mixer, a low-loss matching network based on
$\lambda $
/4 resonators with ground shields is introduced in the terahertz (THz) signal path. Then, the four-stage common-source LNA is utilized to amplify the down-conversion IF signal. Using conventional 40-nm CMOS technology, the implemented THz down-converter exhibits 9.9-dB conversion loss and 39.2-dB noise figure with −6-dBm LO input power at 820 GHz. The core chip occupies only
$0.74\times 0.25$
mm
²
while dissipating 28.6 mW from a 1.1-V voltage supply.