An Assessment of Available Models for the Design of Schottky-Based Multipliers Up to THz Frequencies

Abstract

This paper evaluates the ranges of application and physical limitations of lumped equivalent circuits and drift-diffusion models for the design of THz circuits. The predictions of these models have been compared with a Monte Carlo model, which was considered as a reference, and with measurements from doublers and triplers designed and fabricated by the Jet Propulsion Laboratory. Additionally, the usefulness of Schottky diodes as frequency multipliers above 3 THz is analyzed with the Monte Carlo model.

Monte Carlo Study of 2-D Capacitance Fringing Effects in GaAs Planar Schottky Diodes

“…Indeed, we have performed simulations in a large variety of diodes and all of them follow this universal behavior. However, it is important to remark that the description of the response of PSBDs at very high frequencies (above the range of validity of the standard LEC approach) requires more than a single capacitance to account for complex non-harmonic effects related to velocity saturation, which do depend on the doping level of the epilayer [13]. As observed in Fig.…”

“…The MC simulator is considered as a reference when comparing the different models of Schottky diodes, since, by accounting for all the microscopic phenomena taking place within the devices, it provides a precise description of the semiclassical electron transport even under large signal or high frequency excitations. The main conclusion extracted in [13] is that the operation of Schottkydiode based circuits up to very high frequencies (even above 1 THz) can be correctly described by means of simplified analytical LEC-HB simulators as long as correct values for the resistances and capacitances are used, which can be provided by means of MC simulations.…”

“…We have to stress that the lumped-element circuit (LEC) model is valid in a certain the frequency range, since, even if using correct values for the capacitances and resistances of the PSBDs, such model fails when increasing the input frequency. For this sake, we refer to the results shown in [13], where a review of the available models for the design and optimization of Schottky diode based multipliers is made. Pardo et al, using an harmonic balance circuit solver coupled to a lumpedelement circuit representation of the diode (LEC-HB), compare the results provided by drift-diffusion and hydrodynamic transport models with those obtained with a one-dimensional Monte Carlo (MC) simulator (also coupled with the HB solver, MC-HB).…”

A comprehensive study of cryogenic cooled millimeter-wave frequency multipliers based on GaAs Schottky-barrier varactors

“…The junction capacitance of the Schottky barrier tripleanode stacked varactor diode is modeled as (14) where C jo is the zero-biased junction capacitance and C corr is a first order correction term for edge effects in very small submillimeter-wave diodes. The singularity at high forward bias in (14) is avoided by a linear extrapolation of the junction capacitance above the voltage F c V j where F c is a factor between 0 and 1.…”

A 220 GHz frequency tripler based on 3D electromagnetic model of the schottky diode and the field-circuit co-simulation method

“…The methods currently used to generate terahertz sources include optical methods, vacuum electronics, THz quantum cascade laser, solid‐state electronic devices, etc. In recent years, much attention has been paid to solid‐state electronic device multiplier terahertz source, owing to many advantages, such as high reliability, high spectral quality, compact structure, and low power consumption .…”