A Faster and Effective RF Module/LTCC Design Flow with AMCliterature.cdn.keysight.com/litweb/pdf/5989-9475EN.pdf · 2008. 9. 4. · dielectrics (3D planar) MoM. FEM. A Faster and

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nstewartText BoxA Faster and Effective RF Module/LTCC Design Flow with AMC

A Faster and Effective RF Module/LTCC Design Flow with AMC

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A Faster and Effective RF Module/LTCC

Design Flow with AMC

HeeSoo LEEAgilent EEsof


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Why Electro-Magnetic (EM) Simulation for RF Module/LTCC?

Majority of RF Module/LTCC components are embedded passives, integrated passives, packages, and 3D interconnects

Circuit or analytical models for these components are limited since they are arbitrary geometric physical components

EM simulation brings the best accuracy because:

• EM simulation is based on solving Maxwell’s Equations

• EM simulation can account for all parasitic interactions

• EM simulation can simulate packaging effects

• EM simulation take account for distributed nature of fields inside the structure


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Method of Moments (e.g. Agilent Momentum) – LTCC, Multilayer…

Finite Element Method (e.g. Agilent EMDS) – Packages, Bondwires…

Finite Difference Time Domain (e.g Agilent AMDS) - Antennas

Today’s Three EM Simulation Technologies


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[S]

S-parameters

Your “Virtual Network Analyzer”Your “Virtual Network Analyzer”

Physical Structure

Port 2

ω

source

load

Port 1

sourceload

3D planar metallization

z

Layer [3] 333 ,, σµε h3

Air

Layer [2] 222 ,, σµε h2

Layer [1] 111 ,, σµε h1

Gnd

multilayered medium

E(r)H(r)

Js(r)

Momentum 3D-Planar Electromagnetic Simulator


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Momentum 3D-Planar Electromagnetic Simulator

Momentum simulation process:

Substrate database generationGreen function calculation

Mesh generation

Adaptive frequency loop

For every frequency:

Matrix Load: calculate [Z] elements

Matrix Solve: [Z].[I] = [V]

B1(r) B2(r) B3(r)

I1 I2 I3S1 S2

[Z].[I]=[V]

[S] Direct and iterative solvers, support of machine optimized libraries

Square denseComputationally intensive


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Comparing MoM (Momentum) and FEM (EMDS)

Sparse matrixDense matrix, compression techniques

Simulation time: square

Memory: linear to squareSimulation time: O(N3) (direct), O(N2) (iterative), O(NlogN) (iterative/compr.)

Memory: O(N2), O(NlogN)

Adaptive tetrahedral (volumetric) meshUser controlled metal surface meshing with rectangular, triangular and polygon cells

Unstable at DCStable at DC

Full-wave modeFull-wave and Quasi-static modes

Arbitrarily shaped 3D metals and dielectricsStrips, slots, and vias in infinite, planar dielectrics (3D planar)

FEMMoM


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Typical Three Elements of LTCC Design Process

EM - OK?

YesNo

ModifyLayout

n↓Design

Requirement

Ideal Lumped Passive Design

Physical Component

Design

Feasibility &

Topology

Full EMVerification

OK?

Done

YesNo

ModifyLayout

n↓CouplingAnalysis

More?

No

Yes

Physical Layout

Electrical Design

ComponentDesign

PhysicalDesign

1

2

3


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EM - OK?

YesNo

ModifyLayout

n↓

Physical Component

Design

More?

No

Yes

Critical Iterative Design Loops

Design Requirement

Ideal Lumped Passive Design

Feasibility &

Topology

Full EMVerification

OK?

Done

YesNo

ModifyLayout

n↓CouplingAnalysis

Physical Layout

Component Level Physical Design and EM

Simulations

1

Full Layout Level Physical Design and

EM Simulations

2


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A Method for Faster RF Module/LTCC Design

Circuit level simulations are generally much faster than EM simulations!

Change the physical component design and EM simulations to circuit level simulations by developing

• Highly accurate scalable EM-based circuit level passive models with AMC

EM - OK?

YesNo

ModifyLayout

n↓

Physical Component

Design

More?

No

Yes

Component Level Physical Design and EM Simulations

Circuit LevelPhysical Design

with AMC

Tune/OptComponentParameter

Select AMC Component(Design Kit)

More?

No

Yes


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Advanced Model Composer (AMC)

EM-based passive model library generation technology

• Combines the accuracy of EM with the speed of analytical models with high degree of accuracy, generality, and automation

• Based on Momentum technology

• Unique patented modeling technology

generality

automation

accu

racy

ModelsModelsModels


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freq.

data

Parameters

AMC’s Multi-dimensional Adaptive Parameter Sampling (MAPS) Technology

Different adaptive algorithms are combined to efficiently generate a parameterized global model:

• Adaptive selection of optimal number of data samples along frequency-axis

• Adaptive selection of optimal number of data samples in parameter space

• Adaptive selection of optimal order of the multinomial fitting functions (independent for each parameter)


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Advanced Model Composer TechnologyKey Technology 1: Adaptive Sample Selection

freq

p1

p2

freq

p1

p2

Traditional approachl uniform samplingl some regions of design space

oversampling : waste of resourceundersampling : accuracy issue

AMCl adaptive samplingl reflective exploration technique

quasi-optimal samplingonly relevant samples selected

Patentedtechnology


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Advanced Model Composer TechnologyKey Technology 2: Adaptive Model Selection

freq

p1

p2

freq

p1

p2

Traditional approachl local interpolationl some regions of design space :

over-modeling : ringingunder-modeling : accuracy issue

AMCl global adaptive modelingl Forsythe interpolation technique

quasi-optimal model complexitycovers complete design space

Patentedtechnology


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Two Plate Capacitor AMC Example

Vector

EdgeDistFromCenter

2 Layers parallel plate series capacitor

Single perturbed parameter

• Variable=EdgeDistFromCenter (10~50mils)

• Results in the area from 20x20 to 100x100 mil2

Fast model development time

• 0h 2m19s with 512MB RAM and 2GHz processor PC


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Accuracy of AMC model vs. EM Simulation

50x50mil and 75x75mil parallel plates capacitors compared

• Excellent agreement

• Simulation speed improvement, over 70x

– AMC=0.89 sec

– Momentum=1min 4sec

Once the model is calculated, AMC provides a fast and accurate model development solution

50x50mil

75x75mil

AMC Results EM Results


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Multilayer Inter-Digital Capacitor AMC Example

Multilayer inter-digital capacitor on 3 layers

• Capacitance area: 1mm x 1mm

Characteristic

• 5.8pF @ 2.45GHz

• SRF @ 3.7GHz

1mm1mm


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AMC Parameter Sweep Simulation/Tune/Optimization

AMC models allow designers to perform faster parameter sweep simulation at circuit level

Finding the physical size of desired capacitance is much easier than repeated EM simulations

• Example: Swept simulation of capacitor size


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Helical Inductor AMC Example

Simple to setup and model for Q-factor, Inductance, and SRF

Parameter (Inductor Size) swept simulation allows designers

• To plot inductance and Q-factor vs size of the helical inductor

m_length: ADS swept variable for Center2Edge


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AMC Model Generation 3 Steps (Ex: Helical Inductor)

Step 1-A: Create Layout Component Parameters

• Only one perturbation parameter – Center2Edge

– 4 edges will be perturbed by a single vector

• Type = Nominal/Perturbed

• Nominal (0.3mm) à Perturbed (0.5mm), dx and dy = 0.2mm

Center2Edge


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Step 1-B: Create Layout Component Parameters

• Click “Edit/View Perturbation” menu

• Set perturbation for all four directions

– Select all vertices of right hand side

– Apply dx=0.2 dy=0 to those vertices

– Repeat for other four sides

• Click OK to complete the edit

dX=0.2mm


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Step 2: Create Layout Component

• Menu:

– “Momentum (RF)>Component>Create/Update”

• It creates layout look-alike schematic symbol for schematic

Library Browser


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Step 3: Generate AMC model

• Menu:

– “Momentum (RF)>Component>Advanced Model Composer>Create Model”

• Set layout parameters for model generation

– Sweep Type: Continuous Range

– Min 0.25mm to Max 1.2mm

• Then “Apply” and “OK”

– This will launch model generation process


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Creating AMC Design Kit (1)

AMC models can be packaged into a design kit

• Menu

– “Momentum (RF)>Component>Advanced Model Composer>Design Kit”

• Steps

1. Open a AMC original design that would go into a design kit

2. Click the design kit menu

3. Work with Design kit dialog• See next page


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Creating AMC Design Kit (2)

Assign the name of component

1

Enter the component description

2 3

Select Model

4Finish!

Repeat these processes with all components that will go into the design kit.

By default, AMC design kit is created under the directory $HOME/hpeesof/amc/design_kit


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A Design Flow Example Using AMC

In this design flow example using AMC,

• 2.44GHz L/C Balun topology is used

• 8 metal layers stack-up with Dupont GT943 Green Tape process is used

• A design kit for helical inductors and multilayer inter-digital capacitors is pre-developed


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Balun

A Balun is a device that converts balanced impedance to unbalanced and vice versa

Also Balun provides Impedance transformation

• Balanced to unbalanced transformation

The word Balun is a contraction of “balanced to unbalanced transformer”


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Transmission Line Balun

LC Equivalent Network

Transmission Line Balun

Each quarter wave length transmission lines can be represented by pi-type equivalent

Therefore the transmission line balun can be transformed into a LC balun circuit

Reference:Design Method of a Dual Band Balun and Divider2002 IEEE MTT-S DigestJung-Hyun Sung, Dal Ahn


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LC Balun Final Schematic

High Pass Low Pass

Resonance at fo


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LC Balun Performance at 2.44GHz

Required Inductance = 4.58nH

Required Capacitance = 0.928pF


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LC Balun with AMC components

Design the LC Balun with AMC components

• Inductor size: 0.295mm x 0.295mm = 4.58nH

• Capacitor size: 0.24mm x 0.24mm = 0.928pF

• Frequency: 1.8 ~ 3GHz

de-tuned


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Tuning AMC Design

Tune or optimize the AMC design for a better performance

• The size of Inductor, 0.31mm, improves the performance of LC balun on loss and phase characteristic


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Completed LC Balun Layout

Component Size

• 2.6mm x 2mm

6 land patterns

• 1 input and 2 outputs, 3 ground pins

Component shapes are maintained but vias and some transmission lines are added to make proper connections

ADS Layout

3D View


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Complete EM Verification of LC Balun with Momentum


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Summary

EM simulations are critical to first pass design success for RF Module/LTCC

Agilent EEsof offers a full range of EM simulation technologies

A faster and effective RF Module/LTCC design flow can be achieved by replacing repetitive component level EM simulations with the circuit level AMC models

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nstewartText BoxPrinted in USA, November 15, 20075989-9475EN

Documents

A Faster and Effective RF Module/LTCC Design Flow with AMCliterature.cdn.keysight.com/litweb/pdf/5989-9475EN.pdf · 2008. 9. 4. · dielectrics (3D planar) MoM. FEM. A Faster and