Study On Terahertz Subharmonic Mixer Based On The Planar Schottky Diode

Terahertz (THz) technology is a new cross-disciplinary research area which hasmade rapid development during last two decades, involves electromagnetism,optoelectronics, optics, semiconductor physics, materials science, biology, medicalscience and so on. THz covers wideband electromagnetic radiation area from0.1THzto10THz frequency range and ends connect to the microwave/millimeter wave andinfrared/visible light, respectively. For a long time, there get the application "THz gap"in the electromagnetic spectrum due to the lack of effective THz sources, as well asdetection methods.Among variety THz application systems, the most important technolog is how torealize THz signal down-transformation, which requires THz receiver front-end. Thesub-harmonic mixer is a key component of the receiver front-end. Few kinds ofdifferent diode based mixers have been demonstrated that can be working at THzfrequency. But among aforementioned mixers, only the planar schottky diode basedmixer could working at room temperature,free of harsh low-temperature environments,which usually using liquid helium to achieve. So, this doctoral dissertation focuses onthe planar schottky diode based terahertz subharmonic mixer.This thesis begins with the theoretical analysis and experimental test to the THzplanar schottky diode, for its working as the most important part of the mixer. Thediode's modeling research includes the static HFSS based3D electromagnetic THzplanar schottky diode modeling, the dynamic carrier diffusion simulation to theschottky barrier modeling using SILVACO, and the anti-parallel diode pair'sequivalent circuit study. Then the I-V curve experimental test is done to theanti-parallel terahertz schottky diode. Based on the deduced theoretical analysis, thediode pair's characteristic parameters data are deduced. Finally, the improved highfrequency THz planar schottky diode is studied, after the dissertation makessummarization to the development trend of the THz planar schottky.Following the study on accurate THz planlar schottky diode modeling, take0.38THz sub-harmonic mixer design for example, the dissertation makes detailed discussion on optimization method in the THz sub-harmonic mixer simulation, basedon the system-level accurate THz sub-harmonic mixer modeling method. Afterdescription the study on sub-harmonic mixer's overall non-linear/linear modeling,ADS distributed modeling, and the integral circuit modeling, the thesis makesdiscussion on sub-harmonic mixer's optimal performance, as well as the diodeimpedance on the condition that both RF and LO are under ideal matching. Then, the3-Dimentional THz sub-harmonic mixer cavity block is designed, and the quantitativemachining and assembly error analysis are done by using system-level accurate THzsub-harmonic mixer modeling.Compared with the traditional sub-harmonic mixer test method, based on Y factorhot-cold load method, the realized novel THz noise test system could make equivalentnoise temperature measurement, as well as conversion loss at the same time. Thisnovel THz noise test system's key component is the controllable switching noisesource at the IF chain. In addition, this novel THz noise test system could be directlyapplied as a THz receiver front-end, only on the condition that the controllableswitching noise source is set off.After the dissertation makes experimental and simulation quantified comparativeanalysis to the designed0.38THz sub-harmonic mixer, the end part of the thesisfocuses on some key potential passive circuits' technologies for the THz system, asfollows: The novel rat-race hybrid coupler based on parallel-plate dielectric waveguide(PPDW), which can be carried out as terahertz power splitter/combiner. The novelSine Rectangular Waveguide (SRW) and the Sine Substrate Integrated Waveguide(SSIW) filtering techniques, which can be applied in millimeter wave BPFs. Thechapter also proposes the improved Compact Microstrip Resonant Cell (CMRC)structure, which could be applied to optimize microwave and millimeter wave LPFs, aswell as BPFs. Besides, the improved CMRC structure is further well applied to theTHz sub-harmonic mixer.This dissertation research is done under the joint guidance of EHF Key Laboratoryof Fundamental Science, University of Electronic Science and Technology of China,and United Kingdom Rutherford Appleton Laboratory, as well as UK Space Agency.The study on terahertz sub-harmonic mixer based on the planar schottky diode is veryimportant for our country's fundamental THz technology, could make significant improvement to the THz signal receiver. Besides, this study will help to improve ourfundermantal THz solid-state device technology, THz semiconductor materials andTHz device technology as well.