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).