A 220 GHz subharmonic mixer based on schottky diodes with an accurate terahertz diode model

ABSTRACT This article introduces the design process of a 220 GHz subharmonic mixer with low conversion loss, which is comprised of a pair of anti‐parallel Schottky diodes (SBD). For terahertz circuits, the wavelength of the electromagnetic (EM) wave is very close to the size of devices, which results in complicated parasitic effects. This will leads to a very limited optimization space for circuits design when matching the impedance. To solve this problem, we developed the precise 3D EM planar SBD model and the field‐circuit co‐simulation method to design this terahertz mixer. The diodes are mounted on the quartz‐based suspended microstrip line. The measured results show that the single side band conversion loss is less than 12 dB during radio frequency (RF) range from 211 to 226 GHz and the minimum loss is about 5.9 dB. With the intermediate frequency fixed at 1 GHz, the conversion loss varies from 8 dB to 11.2 dB over the RF bandwidth of 211 to 221 GHz. The mixer can be applied in heterodyne receivers of terahertz systems. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2311–2316, 2016