Filtering amplifiers based on coupled resonator circuits

175 Pages·2015·7.85 MB·English

by  Tianhao He

iltering amplifiers based on coupled
F
resonator circuits
by
ianhao e
T H
AthesissubmittedtotheUniversityofBirminghamforthedegreeofDoctorofPhilosophy
School of Electronic, Electrical and Sys-
temsEngineering
TheUniversityofBirmingham
March2015
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bstract
A
Terahertz (THz) wireless communication systems over 300 GHz can offer broad bandwidth,
buttheyhavelimitations,suchashighprecisionfabricationrequirements,highfabricationcost
and lossy system components. This thesis introduces a THz communication system concept
based on low-cost and high precision micromachining techniques, also a new design approach
to achieve a low loss system for THz communication components and systems. A polymer
(SU-8)micromachinedTHzrectangularwaveguideisdemonstratedinthisthesis,whichshows
that micromachined SU-8 waveguide is a good solution for THz systems with a performance
equivalenttothebestmetalwaveguides.
Inordertominimisethecomponentsandsystemslosses,thisthesisproposesadesignapproach
for filtering amplifiers which removes the lossy planar matching and interconnection circuits
replacing them with waveguide structures to complete the transistor amplifiers design. The
technique also adds filters resulting in a combined filtering amplifier. By using this design
approach, filters are designed together with transistor amplifiers without additional intercon-
nections circuits. To enable this, an analytical design method for filtering amplifiers based on,
the conventional passive coupling matrix for filters is expanded for the amplifiers filters. Novel
coupled resonator circuits, including a general transistor model for the first time is investigated
and a new [T] matrix is introduced to facilitate this additional transistor element. Complete
mathematical formulas are provided in this thesis for the coupled resonator circuits for transis-
toramplifiers.
Two physical design examples at X band are provided in this thesis to demonstrate the usage
of the novel coupling matrix with a simple mathematical synthesis. One microstrip amplifier is
demonstrated using hairpin resonators for 8.4 GHz centre frequency and 500 MHz bandwidth.
A third order Chebyshev bandpass filter is integrated with the amplifier. In this microstrip cir-
cuit,theinterconnectionofthecircuitsbetweenthefilterandtheamplifierisremoved. Inaddi-
tion,awaveguidefilteringamplifierisdemonstratedusingwaveguideresonators. Thetransistor
amplifier is integrated with a quasi-waveguide resonator via a waveguide-to-microstrip transi-
tion. This waveguide amplifier reflects the design considerations and methods for future THz
amplifier developments. Good correlations between mathematical synthesis results and phys-
ical measurements are achieved for the waveguide filtering amplifier, with 3 clearly observed
polesinpassband,verifyingtheorderofthefilters.
cknowledgements
A
ThanksthegraceofGodforgivingmethepassion,wisdom,confidenceandfaithinHim.
I would like to thank my supervisor Prof. Michael J. Lancaster for his constructive ideas,
patientsupervising andcontinuous supportduringmy PhDstudyin theUniversity ofBirming-
ham. Without his assistance and encouragement, the work presented in this thesis may never
havebeenaccomplished.
My appreciation also goes to my colleagues Dr. Jeffrey Powell for his suggestions on active
circuitdesignandassistanceformeasurements;Dr. YingtaoTianforteachingmethemicroma-
chining techniques of SU-8 device; Dr. Xiaobang Shang and Dr Yuliang Dong for the fruitful
discussions on filters, and Prof. Richard G. Humphreys for inspiration of matrix calculations
duringmystudiesattheUniversity.
Mygratitudealsogoestoallresearchgroupmembersfortheirfriendshipsandsupport. Iwould
liketothankthetechniciansMsDonnaJohnson,MrAlanYatesandMrRobertDaviesformak-
ingandteachingmehowtomakemyprintedcircuitsboards.
I also appreciate the financial support from my family and the Engineering School Scholarship
andDudleyDockerResearchScholarshipfromtheSchool.
LastbutcertainlynotleastIwanttoexpressmygreatestgratitudetomyfamilyandfriends,and
BirminghamChineseEvangelicalChurchfortheirfellowshipandprayers.
Knowledgepuffsup,butlove
edifies.
1Corinthians8:1(NKJV)
ontents
C
1 Introduction 1
1.1 ResearchMotivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 ThesisOrganisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 TerahertzCommunicationDevicesandSystems 5
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 TerahertzApplications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.3 TerahertzMicrowaveElectronics . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4 TerahertzWaveguidesandTransmissionLines . . . . . . . . . . . . . . . . . . 10
2.5 TerahertzMicromachiningTechnologies . . . . . . . . . . . . . . . . . . . . . 12
2.5.1 MicromachiningTechnologies . . . . . . . . . . . . . . . . . . . . . . 12
2.5.2 SU-8Photoresist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5.3 SU-8Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6 TerahertzCommunicationPropagations . . . . . . . . . . . . . . . . . . . . . 14
2.7 TerahertzWirelessCommunicationSystems . . . . . . . . . . . . . . . . . . . 16
2.7.1 TerahertzCommunicationSystemBlockDiagram . . . . . . . . . . . 16
2.7.2 MicromachinedCommunicationSystemConcept . . . . . . . . . . . . 17
2.8 TerahertzAmplifierConcept . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3 AWR-3BandRectangularWaveguide 23
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2 ReviewofSubmillimetreRectangularWaveguides . . . . . . . . . . . . . . . 23
3.3 WR-3BandWaveguideDesignConsiderations . . . . . . . . . . . . . . . . . 25
3.4 WR-3BandWaveguideBendDesign . . . . . . . . . . . . . . . . . . . . . . . 26
3.5 WR-3BandRectangularWaveguideDesign . . . . . . . . . . . . . . . . . . . 28
3.6 WR-3BandWaveguideLayouts . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.7 WR-3BandWaveguideMeasurements . . . . . . . . . . . . . . . . . . . . . . 30
3.8 Discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4 CoupledResonatorCircuitsforTransistorAmplifiers 41
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.2 CouplingMatrixReview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.3 CouplingMatrixSynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.4 Then×nCouplingMatrixforCoupledResonatorFilters . . . . . . . . . . . . 45
4.5 TheSmallSignalTransistorModel . . . . . . . . . . . . . . . . . . . . . . . . 48
4.6 The (n + 1) × (n + 1) Coupling Matrix for a Transistor integrated into the last
Resonator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.7 Then×nCouplingMatrixforaTransistorbetweenResonators . . . . . . . . 56
4.8 Two port network for S-parameters generation for the transistor coupled res-
onatorcircuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
5 MicrostripBandpassFilteringAmplifier 64
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5.2 ReviewofBandpassFilteringAmplifier . . . . . . . . . . . . . . . . . . . . . 65
5.3 ASimplifiedFETSmall-SignalModel . . . . . . . . . . . . . . . . . . . . . . 66
5.4 MicrostripFilteringAmplifierDesignOverview . . . . . . . . . . . . . . . . . 68
5.5 MicrostripFilteringAmplifierCouplingMatrixDescription . . . . . . . . . . . 70
5.6 MicrostripFilteringAmplifierResonatorDesignusingCouplingMatrix . . . . 75
5.6.1 ExternalqualityfactorextractionforResonator1 . . . . . . . . . . . . 76
5.6.2 ExternalqualityfactorextractionforResonator3 . . . . . . . . . . . . 78
5.6.3 CouplingcoefficientextractionsforResonator2 . . . . . . . . . . . . . 80
5.7 MicrostripFilteringAmplifierFullImplementation . . . . . . . . . . . . . . . 82
5.8 MicrostripAmplifierMeasurementsandDiscussions . . . . . . . . . . . . . . 87
5.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
6 WaveguideBandpassFilteringAmplifier 91
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
6.2 IntegratedWaveguideAmplifiers . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.3 WaveguideFilteringAmplifierCouplingMatrixSynthesis . . . . . . . . . . . 94
6.4 WaveguideAmplifierCouplingMatrixDesignProcess . . . . . . . . . . . . . 98
6.4.1 ExtractiontheexternalqualityfactorforResonator1 . . . . . . . . . . 100
6.4.2 ExtractionofthecouplingcoefficientforResonator2 . . . . . . . . . . 101
6.4.3 ExtractionoftheexternalqualityfactorforResonator3 . . . . . . . . . 102
6.5 WaveguideAmplifierSimulatedDesignwithaTransistor . . . . . . . . . . . . 105
6.6 MicrostripCircuitforWaveguideFilteringAmplifier . . . . . . . . . . . . . . 109
6.7 WaveguideAmplifierFabrication . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.7.1 Waveguidemetalblocks . . . . . . . . . . . . . . . . . . . . . . . . . 113
6.7.2 Microstripcircuitforwaveguideamplifier . . . . . . . . . . . . . . . . 114
6.7.3 Waveguideamplifierassembly . . . . . . . . . . . . . . . . . . . . . . 115
6.8 WaveguideAmplifierMeasurementsandDiscussions . . . . . . . . . . . . . . 116
6.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
7 ConclusionsandFutureWork 119
7.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7.2 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
A One-portmeasurementforexternalqualityfactor 125
B WR-3RectangularWaveguideFabricationProcedures 128
References 130
hapter
C 1
ntroduction
I
1.1 Research Motivation
Without direct wired connections, wireless communication systems transfer information be-
tween two points with sound, infrared, optical, radio frequency or microwave energy. This
thesis focuses on the wireless communication systems using RF or microwave waves to prop-
agate signals. Wireless communications have applications for broadcast radio and television,
cellulartelephoneandnetworkingsystems,directbroadcastsatellitetelevisionservice,wireless
local area networks, paging systems, Global Positioning System (GPS) service, and radio fre-
quency identification systems [1]. This thesis focuses on the communication components and
systems. Forcommunicationsystemcircuits,currentresearchhasdemonstratedabandpassfil-
ter at the centre frequency of 700 GHz [2] at the University of Birmingham with the long term
objectivesofproducingcommunicationsystemsatterahertzfrequency.
Wirelesscommunicationsystemscommonlyrequirereceiverswithhighselectivityusingfilters,
for example, where channelisation is implemented or high power radiators are present adjacent
tothereceiver’sbandofinterest. Additionally,lownoiseamplifiers(LNA)arethefundamental
components for microwave communication system at the receiver ends. Achieving optimum
performance for LNA designs requires two key criteria (i) optimum impedances are presented
1