A 225–300 GHz broadband frequency tripler using accurate series resistance model

Abstract This paper proposed an accurate series resistance model tailored for Schottky diode‐based terahertz multipliers. Compared to the conventional electrothermal model (E‐T model) only considering thermal effects, this model comprehensively accounts for both thermal and frequency effects of the series resistor components, including the temperature‐dependent epilayer resistance ( R epi ) and the temperature‐frequency‐dependent spreading resistance ( R spreading ). The evaluation of thermal effects relies on steady‐state thermal simulation and the corresponding electrothermal model. Notably, the frequency‐dependent spreading resistance part is derived from the fitting conductivity of doped buffer layers and extracted by auxiliary three‐dimensional electromagnetic simulations. Based on this model, a balanced 225–300 GHz frequency tripler with AlN substrate has been designed and manufactured. By introducing this model, a significant improvement in the consistency between simulated and measured results has been achieved compared to the single E‐T model, regardless of whether the input power is low (80 mW) or high (160 mW).