Electrical and Noise Modeling of GaAs Schottky Diode Mixers in the THz Band

This paper presents a simulation tool for the analysis and design of Schottky mixers which is able to evaluate self-consistently both the conversion losses and the noise temperature. The tool is based on a Monte Carlo model of the diode coupled with a multi-tone harmonic balance technique. A remarkable feature of this tool is that it avoids the need of analytical or empirical models. The validation of the tool has been carried out by comparing simulation results with measurements of mixers published in the literature up to 2.5 THz. The usefulness of Schottky diodes as frequency mixers above 2.5 THz is analyzed. Additionally, the range of application and the limitations of simpler simulation tools based on lumped equivalent circuits or drift-diffusion models have been evaluated using the Monte Carlo model as a reference.