plannar transmission lines

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Planar Transmission LinePlanar Transmission Line

Technologies Technologies

CMB Polarization Technology Workshop NIST/Boulder

Edward J. Wollack

Observational Cosmology Laboratory Observational Cosmology Laboratory NASA Goddard Space Flight CenterNASA Goddard Space Flight Center

Greenbelt, MarylandGreenbelt, Maryland



Overview Overview

Selected Planar Transmission Line TopologiesSelected Planar Transmission Line Topologies

Planar Transmission Line ApplicationsPlanar Transmission Line Applications Example: Planar Microwave FiltersExample: Planar Microwave Filters

Component Repeatability Component Repeatability

System Level ConsiderationsSystem Level Considerations

Technical Readiness Level (TRL) Technical Readiness Level (TRL)

Future Development MilestonesFuture Development Milestones



Planar Transmission LinesPlanar Transmission Lines

TEM TEM

Conductor

Dielectric

Electric field

QuasiQuasi-- TEM TEM

• Phase Velocity

• Impedance Level

• Number Propagating Modes

• Field Configuration

QuasiQuasi-- TEM TEM NonNon-- TEM TEM

Microstrip

Microstrip withground plane slot

+

--

Coplanar

waveguide

GroundedCoplanar

Finite width

CoplanarWaveguide

Even-mode

Odd-mode

-+

+- -

Stripline

Parallel Plate

Slotline

Finite width

Slotline

+ -

+ -

+

-



Planar Transmission Lines:Planar Transmission Lines:

Characteristics and ApplicationsCharacteristics and Applications

Blocking FiltersBlocking Filters~0.1~0.1 – – 11MediumMediumStrip LineStrip Line

Antennas, Resonance Suppression, Antennas, Resonance Suppression,

Filters, TransitionsFilters, Transitions~0.6~0.6 – – 1.81.8MediumMediumMicrostrip LineMicrostrip Line

with ground plane slot with ground plane slot

Filters, Hybrids, High QFilters, Hybrids, High Q--ResonatorsResonators~0.6~0.6 – – 22Low Low Coplanar WaveguideCoplanar Waveguide

Antennas, Transitions, Power Antennas, Transitions, PowerCombinersCombiners

~1.2~1.2 – – 33HighestHighestFiniteFinite-- Width Slotline Width Slotline

(i.e., Edge(i.e., Edge--Coupled Line)Coupled Line)

Antennas, Phase Shifters Antennas, Phase Shifters~1.2~1.2 – – 2.42.4HighHighSlotlineSlotline

Filters, Hybrids, High QFilters, Hybrids, High Q--ResonatorsResonators~0.2~0.2 – – 1.41.4Low Low Microstrip LineMicrostrip Line

Antennas, Transitions Antennas, Transitions~0.4~0.4 – – 1.61.6Low Low ParallelParallel--Plate LinePlate Line

Typical Sensor Circuit Examples: Typical Sensor Circuit Examples:ImpedanceImpedance

[ [ ZZoo ] ]

RelativeRelative

LossLoss



Planar Microwave FiltersPlanar Microwave Filters

Methods to control spurious response and radiationMethods to control spurious response and radiation Extending fundamental propagation mode bandwidth:Extending fundamental propagation mode bandwidth:

Limit width/length ratioLimit width/length ratio Thin dielectric Thin dielectric

Suppress undesired modes:Suppress undesired modes: Symmetric designSymmetric design

Packaging Packaging

Transmission zeros insertion Transmission zeros insertion

Transmission line alteration Transmission line alteration

Stepped impedance lineStepped impedance line Defected ground structureDefected ground structure

Wiggly coupled lines Wiggly coupled lines

OtherOther……

Lumped Element FilterLumped Element Filter

CoupledCoupled--Line BandLine Band--pass Filterpass Filter

Quarterwave BandQuarterwave Band--stop Filterstop Filter

Z0

Z0

T r a n s m i s s i o n ( d B )

Frequency (GHz)

Out

In

Actual stop-band responses(with spurious resonance frequencies)

Desirable stop-bandfrequency response (ideal

lumped-element filter)

10 100 1000

Source: R. K Hoffman, “Handbook of Microwave

Integrated Circuits,” Artech House, 1987.



Filter Designs: BandFilter Designs: Band--PassPass

Figure 2. Top left: The lumped element model for a 3rd order LC

bandpass filter [3,4]. Lower left: The layout for the corresponding

SONNET model. Right: The transmittance for the lumped-elementmodel (solid) and the full wave SONNET calculation (dashed).

Figure 1. Upper left: The layout of a resonant stepped impedance filter

(GSFC/GATech [2]); Lower left: A lumped element filter with CPW

inductors (JPL, [4]); Right: A triplexer (3-element filter bank) connected to

a broad band antenna (UC Berkeley, [1]).

Figure 3. FTS Spectra for integrated antenna+filters, from the Berkeley

group ( Left ), and the JPL group ( Right ). Devices for 90 and 150GHz bands

are shown. All spectra are normalized individually. The red curve in theright panel indicates atmospheric transmission at ballooning altitudes.

References:

[1] O’Brient, R. et al., v151,p459, JLTP 2008

[2] U-yen K. et al., v54, i3,p1237, IEEE MTT, 2006.

[3] Goldin, A. et al., v4855,

p163, proc. SPIE, 2003

[4] Kuo, C. et al., to appearin proc. SPIE, 2008



Filter Design: Thermal BlockingFilter Design: Thermal Blocking

-100

-80

-60

-40

-20

0

0 10 20 30 40 50Freqeuncy (GHz)

d B | S 2 1 | , d B | S 1 1 | Measured

EM Simulation

Circuit model

S11 mea

S11 EM

S11 ckt

S11

S21

# 1

# 2

# 3# 4# 5

# 6# 7

# 2

# 3# 4 # 5

# 6# 7

Microwave Blocking filter Enclosed Cavity

Input Pocket

5.85 mm

3.34 mm

13.95 mm

7.8 mm

U-Yen, K. and Wollack, E.J., “Compact Planar Microwave Blocking Filter”, 2008, 38th European Microwave Conference, Amsterdam, Netherlands, accepted.



Process RepeatabilityProcess Repeatability

Process Variations:Process Variations: Component GeometriesComponent Geometries

Conductor Thickness and SlopeConductor Thickness and Slope Substrate Thickness and EtchSubstrate Thickness and Etch

Packaging Effects and VariationsPackaging Effects and Variations

Material EffectsMaterial Effects Critical Temperature, ComplexCritical Temperature, Complex

Surface Impedance, Step CoverageSurface Impedance, Step Coverage……

Dielectric ConstantDielectric Constant……

High Material Uniformity High Material Uniformity ……

Low Dimensional Variability Low Dimensional Variability ……

Modeling and Design:Modeling and Design: Circuit Parameter Sensitivity Circuit Parameter Sensitivity ……

Material Parameter KnowledgeMaterial Parameter Knowledge……

Slope

Conductor Thickness

Substrate Over-etch

SEM image of a co-planar waveguide structure

Return loss

Transmission

εr=9.6

εr=7.9



System Level ConsiderationsSystem Level Considerations Advantages: Advantages: Compatible with integration on aCompatible with integration on a

detector chipdetector chip

Can achieve high optical coupling Can achieve high optical coupling

efficiency efficiency Compact sizeCompact size

Can lead to parts with highCan lead to parts with highrepeatability, yield and low processrepeatability, yield and low process variation. variation.

Does not link frequency andDoes not link frequency andangular band definitionangular band definitionrequirementsrequirements

Transmission line thermal Transmission line thermalrequirements subdominant torequirements subdominant todetector requirementsdetector requirements

Transmission line loss above gap Transmission line loss above gapfrequency limits out of band powerfrequency limits out of band power

Synthesis, modeling, andSynthesis, modeling, andsimulation design tools at relatively simulation design tools at relatively mature levelsmature levels

DisadvantagesDisadvantages:: Geometries and materials canGeometries and materials can

require tighter and greater controlrequire tighter and greater controlover process tolerances (relative toover process tolerances (relative to

their quasitheir quasi--optical counterparts) tooptical counterparts) toinsure desired operationalinsure desired operationalperformanceperformance

Care must be taken in the overallCare must be taken in the overalldesign not to allow supporting design not to allow supporting circuitry to drive sensor fabricationcircuitry to drive sensor fabrication

and test complexity/risk and test complexity/risk Each singleEach single--mode transmissionmode transmission

line channel experiences anline channel experiences anindependent filter which must beindependent filter which must becharacterized in flightcharacterized in flight

Polarimeter implementationsPolarimeter implementations

which use different filters to form which use different filters to formStokesStokes--Q need wellQ need well--matchedmatchedresponse to minimize relativeresponse to minimize relativecalibration and foreground errorscalibration and foreground errors

Cryogenic array characterizationCryogenic array characterizationand screening capabilities presently and screening capabilities presently

at relatively low level of maturity at relatively low level of maturity



Technical Readiness Level Technical Readiness Level Prototype variants on the required passive circuit elements toPrototype variants on the required passive circuit elements to

support CMB polarization science requirements have or will reachsupport CMB polarization science requirements have or will reach

TRL ~ 5 under the on going funding cycle. Examples include: TRL ~ 5 under the on going funding cycle. Examples include: BandBand--Pass FiltersPass Filters

Bolometer to Antenna Thermal BreaksBolometer to Antenna Thermal Breaks

Superconducting Transmission LinesSuperconducting Transmission Lines

Normal Metal Absorber Structures and TerminationsNormal Metal Absorber Structures and Terminations

Power CombinersPower Combiners Thermal Blocking Filters / Bias Chokes Thermal Blocking Filters / Bias Chokes

OtherOther……

Continued support in this area will be required to produce highContinued support in this area will be required to produce high

optical efficiency sensors and field representative devices in f optical efficiency sensors and field representative devices in f ully ully integrated systems.integrated systems.

Further design and fabrication iterations will also be requiredFurther design and fabrication iterations will also be required toto validate large numbers fully testable structures with acceptable validate large numbers fully testable structures with acceptablelevels of yield and reliability forlevels of yield and reliability for spacebornespaceborne applications....applications....



Future Development MilestonesFuture Development Milestones

So are we ready? Is what we have built what we want?So are we ready? Is what we have built what we want?

Production of highest efficiency pixels possible is the key toProduction of highest efficiency pixels possible is the key to

controlling instrument cost and mission risk controlling instrument cost and mission risk within allocated within allocatedresources (e.g., design focal plane area, cooling power,resources (e.g., design focal plane area, cooling power,

massmass…… ) )

Demonstrated filter efficiencies for example are arguably anDemonstrated filter efficiencies for example are arguably anexcellent start, however, from a systems perspective oneexcellent start, however, from a systems perspective one

might inquiremight inquire……

Where did the remaining power go? Where did the remaining power go?

What is a reasonable target for the filter performance? What is a reasonable target for the filter performance? Given an acceptable targetGiven an acceptable target – – what design margins are required to what design margins are required to

realistically meet the desired instrument sensitivity with thisrealistically meet the desired instrument sensitivity with this

approach?approach?



Planar Circuits: Loss MechanismsPlanar Circuits: Loss Mechanisms

2

2

0

0

3

1

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛ ⋅⋅=

eff

rad

hk

Z G

ε

η

π ο

14

1

−⋅=

r

ch

c f

ε

W Z

Rsc

0

=α

( )δ

ε

ε

ε

ε α tan

1

1

20 ⋅

−

−⋅⋅=

r

eff

eff

r d k

DielectricDielectric

ConductorConductor

Reactive MismatchReactive Mismatch

RadiationRadiation

FreespaceFreespace (3D)(3D)

Surface Wave (2D)Surface Wave (2D)



Planar Circuits: DesignPlanar Circuits: Design

Material Selection and Fabrication:• Material parameters : εr μr σ

• Physical Dimensions and Tolerances• Realizable Topologies

• Number of layers

• Apertures, Air Bridges, Vias, etc.

• Dimensional Tolerances

Material Selection and Fabrication:Material Selection and Fabrication:• Material parameters : εr μr σ

• Physical Dimensions and Tolerances• Realizable Topologies

• Number of layers

• Apertures, Air Bridges, Vias, etc.

• Dimensional Tolerances

Design and Synthesis:• Extract Circuit Elements

• Impedance Contrast• Propagation Constant

• Transmission Line Model

• Full-wave Analysis

Design and Synthesis:Design and Synthesis:• Extract Circuit Elements

• Impedance Contrast

• Propagation Constant

• Transmission Line Model

• Full-wave Analysis

Circuit Validation:• Compare Models with

Observation• Reliability/Life Testing

Circuit Validation:Circuit Validation:• Compare Models with

Observation• Reliability/Life Testing



Planar Circuits: ExamplesPlanar Circuits: Examples

Hybrids

Filters

Phase Shifters

Bias Chokes

Terminations

Artificial transmission line

Power divider Antennas

plannar transmission lines

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