CHEN, Jason 2018.04.

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Application Engineer, Keysight Technologies
• Basics of Spiral Inductors
• Inductor basics
• Technology basics
• Inductor P-Cell Design on ADS
• Basic of ADS Environment
• The Easy Way: Coilsys
• The Hard Way: Use AEL Macro
• Inductor Simulation Using Momentum
• Basic of emSetup
• Recommended Setting
• Inductor Modeling on ADS
• The Easy way: Coilsys Synthesis, Finder & AMC
• The Hard way: Expression and Optimization

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Ref: C. Yue, C. Wong, “Design Strategy of On-Chip Inductors for Highly Integrated RF Systems”, 1999.
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 I M PA C T S O F E A C H C O M P O N E N T S

• Ls: Low-frequency inductance. • Design Parameters:

• D: outer diameter
• Rs: Low-frequency resistive loss of a metal and
• W: metal width
skin effect.
• S: spacing between turns
• Cs: arises from the overlap of the cross-under • N: number of turns
with the rest of the spiral. The lateral
• Process Parameters:
capacitance from turn to turn is included.
• Substrate resistivity
• Cox: capacitance between the spiral and the • Metal option selection
substrate • Thickness of top metal
• Metal layer to form spiral
• Rsi: substrate loss
• Csi: capacitance of the substrate

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 P E R F O R M A N C E M AT R I X

• Inductance (Ls) • Inductance Calculation

• Single-ended Inductance
• Differential Inductance 𝑖𝑚𝑎𝑔 𝑍11
𝐿=
2𝜋𝑓
• Quality Factor (Q)
• Single-ended Quality factor • Quality Factor Calculation
• Differential Quality factor
𝑖𝑚𝑎𝑔 𝑍11
𝑄=
• Self-Resonate Frequency (Fsr) 𝑟𝑒𝑎𝑙 𝑍11
• Single-ended Fsr
• Differential Fsr • 2-port to Differential 1-port

𝑍𝑑𝑖𝑓𝑓 = 𝑍11 + 𝑍22 − 𝑍12 − 𝑍21

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BASIC OF TECHNOLOGY

• Semiconductor

• Dielectric Layer

• Conductor

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 W O R K S P A C E , L I B R A R Y, C E L L A N D V I E W

• Workspace
• The main project directory.
• Can contain many libraries. Each library can have
different technology.
• Library
• Refer to specific technology, that means the layer
definition and unit is fixed.
• Cell
• Designs or test-benches in one library.
• Can contain many views for different types of
design
• View
• Different types of design such as schematic, layout
and emModel.
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TECHNOLOGY SETUP

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T H E E A S Y W AY

For the first time, ADS should be restarted to load essential scripts.

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U S E R _ I N P U T. A E L

Layer name is case sensitive

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C R E AT E I N D U C T O R P - C E L L

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U S E P - C E L L I N A N O T H E R L AY O U T

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• Check User_Input.ael
• Check Coilsys in App Manager
• Restart ADS
• Create a P-cell using Coilsys
• Use created P-cell in another layout

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USE AEL MACRO

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• Write AEL script in text editor
• Create boot.ael for library
• Load AEL script in boot.ael
• Configure P-cell Layout

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 INTRODUCTION TO MOMENTUM

• Support Arbitrary Multi-layer structures

• High accuracy simulation for complex
parasitics and EM coupling effects.
• Integrated in both ADS and Virtuoso
Environment.
• Essential for passive components, patch
antenna simulation and verification in RFIC,
MMIC, PCB and RF modules.

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MOMENTUM BASICS

Open Boundary
Lateral coupling

Vertical coupling

Vias

Dielectric Layer1
Delectric Layers are extended
Dielectric Layer2 to infinity

Different materials on the

same Z-coordination is
not supported

Arbitrary conductors crossing

layers are not supported

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MOMENTUM BASICS

・ Momentum is a 3D planar EM solver.

・ Sidewall current flow, including vertical and horizontal, of thick metal is
considered.

Top Bottom horizontal

Sidewall vertical
Sidewall horizontal

ground plane

Sidewall coupling
effect can be
simulated.

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MOMENTUM BASICS

• Thick conductors can be analyzed in

Momentum
• 3 Types of setting for Conductors

1. 3D Distributed 2. 2D Distributed 3. Sheet

Current densities of top, Only vertical current is Sidewall current is not considered
bottom and sidewall are all considered at sidewall Used for specific conditions
considered. ・Mesh shield GND
Recommended Setting ・Slow wave GND
・Patterned GND for eddy
current reduction

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MOMENTUM BASICS

1. 3D Distributed Model
Vertical and Horizontal current of vias are considered
For high accuracy

2. 2D Distributed Model
Vertical current of Vias are considered
Recommended for IC. Usually via array is simplified to single via.
There is no horizontal current of merged vias.

3. Lumped Model
Vias are replaced with LR lumped model. Meshes are not generated
for vias. Mutual inductance and self, mutual capacitance are not
considered.

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RECOMMENDED SETTING

Tips Reason

1. Using RF mode Due to advantage of simulation speed.

Layout size is relative small compared to wavelength, the
effect of surface radiation can be ignored in the most cases.
Assume the induced current flow on Si substrate is small.

2. Recommended Mesh Density is Matrix size (number of meshes) is a trade-off to accuracy.

50 ~ 100 cells/wavelength This setting can fulfill the certification constrains of most
foundries.
3. 3D Distributed model for Thick For highest accuracy
Conductors

4. 2D Distributed model for Vias Via array is merged to single via. There is no horizontal
current in merged via.

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RECOMMENDED SETTING

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RECOMMENDED SETTING

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RECOMMENDED SETTING

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RECOMMENDED SETTING

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COILSYS SYNTHESIS

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COILSYS SYNTHESIS

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COILSYS INDUCTOR FINDER

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A U T O M AT I C M O D E L C O M P O S E R

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EXTRACTION USING EXPRESSION

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F I N D I N D U C T O R U S I N G O P T I M I Z AT I O N

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• Coilsys is a new tool in ADS2017 for P-cell creation, model synthesis and inductor finding. It
provides a turn-key solution for user to design and optimize inductors and transformers quickly.
• To obtain more flexibility, users can use AEL macro for customized layout. AMC can create EM
based model for parameterized layout. The parameterized layout is not only useful in inductor
design but also in antenna, package and other passive components.
• Momentum provides a fast and accurate EM solver for inductor simulation. FEM can be an
alternative in ADS environment.

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