Low-noise balanced mixer for 300-GHz band based on Fermi-level managed barrier diode on SiC platform

Abstract

We developed a terahertz-wave balanced mixer fabricated on a SiC substrate using epi-layer-transferred InP/InGaAs Fermi-level managed barrier (FMB) diodes. The FMB diodes were monolithically integrated with waveguide couplers, a 90-degree hybrid circuit, and low-pass filters. The fabricated mixer was then assembled in a two-input-port module with a broadband transimpedance amplifier and exhibited an intermediate frequency bandwidth of about 26 GHz with good inter-port isolations of more than 13 dB. The obtained minimum noise equivalent power was as low as 2 × 10^-19 W/Hz in the fundamental mixing mode at around 300 GHz for a local-oscillator power of about 400 μW.