Development of GaAs subharmonic mixer for THz communication

In this study, we report GaAs SBD-based subharmonic mixer for THz communication in the 220-330 GHz band. n GaAs:Si and n++ GaAs:Si were grown on semi-insulating GaAs substrate by using metal-organic chemical vapor deposition. Antiparallel(AP)-SBD was fabricated using the i-line stepper. The schottky junction, defined to be less than 1 um, has been composed of Ti/Pt/Au. The I-V and C-V characteristics of the fabricated AP-SBD were measured for the ideal factor, series resistance, current parameter, junction capacitance and parasitic capacitance. RF matching and LO and IF filters were designed with HFSS capable of 3D electromagnetic wave computational simulation. We also simulated the GaAs subharmonic mixer circuit using the nonlinear analysis of ADS. The conversion loss of the mixer module was measured and compared with the computational simulation results. Finally, we demonstrate the THz communication with 50 Gbps QPSK signal in the 300 GHz band.