A 0.75-1.1 THz Fourth-Harmonic Mixer Using GaAs Monolithic Integrated Technology

A 0.75-1.1THz fourth-harmonic mixer is proposed and manufactured using GaAs monolithic integrated technology. The Schottky diode packages and peripheral passive circuits are integrated on the same GaAs substrate, and a micron-level alignment between the diode and the peripheral circuit is achieved by using lithography sputtering to fabricate the metal structure. The 3μm ultra-thin GaAs substrate is used as the circuit substrate of the terahertz fourth harmonic mixer. In order to prevent the bending caused by too long substrate, the T-type structure is used to distribute part of the circuit to the transverse length of the substrate, so as to reduce the overall length of the substrate. Experimental results show that the conversion loss of the proposed terahertz fourth-harmonic mixer varies from 23.2 to 45 dB in the range of 0.75-1.1 THz. The best conversion loss of about 23.2 dB is measured at 1.01 THz.