Development of 0.34 THz Sub-Harmonic Mixer Combining Two-Stage Reduced Matching Technology with an Improved Active Circuit Model

In this paper, a high-performance 0.34 THz sub-harmonic mixer combining two-stage reduced matching technology with an improved active circuit model is established and analyzed. The mixer’s improved active circuit model is realized by decomposing passive functional models into basic transmission line units and their impedance matching and filtering are realized through automatic optimization. The improved active circuit model takes out the RF (radio frequency) transition model separately to set an optimization goal instead of operating directly in the mixing circuit. Compared with traditional active circuit models in the SDM (subdivision design method) and GDM (global design method), it provides a massive optimization space, larger working bandwidth, and better results. In the RF frequency range of 320–360 GHz, the SSB (single sideband) conversion loss of the 0.34 THz sub-harmonic mixer is below 9.5 dB and the RF return loss is less than 12 dB.