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MMIC Design and Technology Passive Elements Instructor Dr. Ali Medi Lecture 3 Passive Elements
MMIC Design and TechnologyPassive Elements
Instructor Dr. Ali Medi
Lecture 3 Passive Elements
Types of Passive ElementsTypes of Passive Elements
• ResistorsResistors• Capacitors
T i i Li• Transmission Lines• Inductors• Couplers
Lecture 3 Passive Elements
ResistorResistor
Lecture 3 Passive Elements
Types of ResistorsTypes of Resistors
• Thin FilmThin Film– NiCr
50 Ω/sq– 50 Ω/sq• Bulk
G– GaAs– 700 Ω/sq
Figures from Text
Lecture 3 Passive Elements
Resistor Equivalent CircuitResistor Equivalent Circuit
Lecture 3 Passive Elements
CapacitorCapacitorAC rεε 0
dC r0=
=ε 13 GaAs
FxFx
r
1512 1085810858 −− ==
=
ε
ε 13 GaAs
mmx
mx0 1085.81085.8 ==ε
Typical chip has d= 0 1mmTypical chip has d= 0.1mm
What is C in pF/mm2
Lecture 3 Passive Elements
MIM CapacitorMIM Capacitor
Thin Dielectric layer to produce high values of capacitance
21200pF/mm2
Lecture 3 Passive Elements
MicrostripMicrostrip
ImRe
εεεε += j
http://mcalc.sourceforge.net/ Im
Retanεεδ =
Im
GaAs =ε 13
=δεtan
r
0.0016 @ 10GHz
Lecture 3 Passive Elements
Effective Dielectric ConstantEffective Dielectric Constant
Lecture 3 Passive Elements
ImpedanceImpedance
Lecture 3 Passive Elements
Wavelength λWavelength λ
m fc λ=
m
m
cc
f
0=r
m ε In GaAs
1038 90 cmxcc ==sec
103.813
xcm ==
At 10GHz f = 0.83 cm
Lecture 3 Passive Elements
Propagation ModesPropagation Modes
• Microstrip supports TEM modesMicrostrip supports TEM modes– λg=cm/f
Must be thin to avoid higher order modes• Must be thin to avoid higher order modes• Thin means H < 0.1 λ
– <0.8mm at 10GHz– <0.25mm at 30GHz
Lecture 3 Passive Elements
Transmission Line LossesTransmission Line Losses
• Skin DepthSkin Depth
f1
=μσπ
δfμσπ
=σ Conductivity gold = 4.5 x 107 S/m
Hx 7104 −= πμ
Lecture 3 Passive Elements
m
Current flow on microstripCurrent flow on microstrip
Current flows on inner surfaces
Lecture 3 Passive Elements
Simple InductorsSimple InductorsFrom Text
Lecture 3 Passive Elements
Inductor DesignsInductor Designs• May require Electromagnetic SolutionMay require Electromagnetic Solution
– Some design equations available– Use foundry supplied modelsUse foundry supplied models
Lecture 3 Passive Elements
Vias and GroundingVias and Grounding
Lecture 3 Passive Elements
Impedance ExampleImpedance Example
0 07Consider 0.1 mm thick GaAsFind W for 50Ω line
0.07mm
What is Zo of a line that has W=0.03mm and H=0.1mm
65Ω
50Ω 0.03mm
What is return loss of this structure on 0.1mm thick GaAsAssume that the line on the right has infinite length.
Lecture 3 Passive Elements
Reflections at Multiple InterfacesReflections at Multiple Interfaces
50Ω 65Ω 50Ω
Pinρ1 ρ2
50Ω 65Ω 50Ω
Pref
λg/4Pref = 0
ZL – Z0
λg/4
ρ = L 0
ZL + Z0ρ2 = - ρ1
Lecture 3 Passive Elements
SplitterSplitter
Lecture 3 Passive Elements
First MMIC LayoutFirst MMIC Layout
Lecture 3 Passive Elements
