Design of a 170–260 GHz Broadband Frequency Tripler Using Multi-Objective Optimization

The design of terahertz (THz) solid-state frequency triplers is challenging due to tightly coupled electromagnetic (EM) and nonlinear behaviors. We employ a multi-objective optimization (MOO) framework, with EM-circuit co-simulation, to optimize a 170–260 GHz broadband frequency tripler. Using band-averaged input and output power efficiencies as objectives, the algorithm explores 36 structural parameters spanning the diode region, matching networks, and filters and yields a set of Pareto-optimal solutions. A fabricated design validated our approach: with an input power of 200 mW, the measured conversion efficiency is ≥3% across 170–260 GHz and ≥5% over 185–245 GHz, with a peak of 7.8% at 202 GHz. These results confirm that MOO enables efficient exploration of design trade-offs and practical high-performance THz multipliers.