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

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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 (Repi) and the temperature‐frequency‐dependent spreading resistance (Rspreading). 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).
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Received: 6 May 2024
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Revised: 19 July 2024
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Accepted: 10 September 2024
DOI: 10.1002/mop.34333
RESEARCH ARTICLE
A 225300 GHz broadband frequency tripler using
accurate series resistance model
Haomiao Wei |Yong Zhang |Xingzeng Cha |Huali Zhu |Yang Chen
University of Electronic Science and
Technology of China, Chengdu, China
Correspondence
Yong Zhang and Yang Chen, University
of Electronic Science and Technology of
China, Chengdu 611731, China.
Email: yongzhang@uestc.edu.cn and
idlechess@163.com
Funding information
China Postdoctoral Science Foundation,
Grant/Award Number: 2024M750353
Abstract
This paper proposed an accurate series resistance model tailored for Schottky diode
based terahertz multipliers. Compared to the conventional electrothermal model
(ET model) only considering thermal effects, this model comprehensively accounts
for both thermal and frequency effects of the series resistor components, including
the temperaturedependent epilayer resistance (R
epi
) and the temperature
frequencydependent spreading resistance (R
spreading
). The evaluation of thermal
effectsreliesonsteadystate thermal simulation and the corresponding electro-
thermal model. Notably, the frequencydependent spreading resistance part is
derived from the fitting conductivity of doped buffer layers and extracted by aux-
iliary threedimensional electromagnetic simulations. Based on this model, a bal-
anced 225300 GHz frequency tripler with AlN substrate has been designed and
manufactured. By introducing this model, a significant improvement in the con-
sistency between simulated and measuredresultshasbeenachievedcomparedto
thesingleET model, regardless of whether the input power is low (80 mW) or high
(160 mW).
KEYWORDS
balanced frequency tripler, electrothermal model, Schottky barrier diode, series resistance,
spreading resistance, terahertz
1|INTRODUCTION
Terahertz wave (0.110 THz) has been developing rapidly
and gaining great attention in numerous potential ap-
plications like spectroscopic and imaging techniques,
atmospheric physics, highspeed communication, and
biomedicine instruments, as it is the last unexploited
electromagnetic spectrum.
13
One of the cornerstones in
terahertz technology development is the terahertz source.
At present, the planar Schottky barrier diodes (SBDs)
based frequency multipliers have been one of the most
attractive device technologies for terahertz sources owing
to its merits of high reliability, low cost, and operation at
room temperature.
4,5
Till now, the operating frequencies
of multipliers can achieve up to 2.7 THz.
6
However,
within the realm of existing frequency multipliers, there
typically exists a gap between simulation and measure-
ment. As the frequency escalates, this gap widens, posing
an urgent requirement for accurate diode models.
Currently, electrical parametersfilled SPICE model, also
known as the lumped element equivalent circuit (LEC)
model, combined with simplified threedimensional elec-
tromagnetic (3DEM) diode model, is widely used in multi-
plier design.
79
This model is straightforward, practical and
can obtain the parasitic parameters but lacks thermal effects.
Therefore, a series of ET diode models are developed to
characterize the power drop phenomenon and provide
power handling capability expectations for diode thermal
management issues.
1017
Aselfconsistent ETmodelwitha
multianode thermal coupling matrix is proposed,
14
which
Microw Opt Technol Lett. 2024;66:e34333. wileyonlinelibrary.com/journal/mop © 2024 Wiley Periodicals LLC.
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