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 LEE
Agilent EEsof
Page 1
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 2
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Today’s Three EM Simulation Technologies
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
Page 3
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Momentum 3D-Planar Electromagnetic Simulator
Physical Structure
z
Air
multilayered medium
3D planar
metallization
H(r)
E(r)
ε , µ σ h 1
Layer [1] 1 1,
1
ε , µ σ h 2
Layer [2] 2 2,
2
Port 1
source
ε , µ σ h 3
Layer [3] 3 3,
3
Gnd
source
ω
load
J s (r)
Port 2
load
[S]
S-parameters
Your “Virtual Network Analyzer”
Page 4
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Momentum 3D-Planar Electromagnetic Simulator
Momentum simulation process:
Substrate database generation
Green function calculation
Mesh generation
B 1 (r) B 2 (r) B 3 (r)
I 1 I 2
I 3
S 1
S 2
[Z].[I]=[V]
[S]
Adaptive frequency loop
For every frequency:
Matrix Load: calculate [Z] elements
Square dense
Computationally intensive
Matrix Solve: [Z].[I] = [V]
Direct and iterative solvers,
support of machine optimized libraries
Page 5
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Comparing MoM (Momentum) and FEM (EMDS)
Stable at DC
MoM
Strips, slots, and vias in infinite, planar
dielectrics (3D planar)
Full-wave and Quasi-static modes
User controlled metal surface meshing with
rectangular, triangular and polygon cells
Dense matrix, compression techniques
Simulation time: O(N 3 ) (direct), O(N 2 )
(iterative), O(NlogN) (iterative/compr.)
Memory: O(N 2 ), O(NlogN)
FEM
Arbitrarily shaped 3D metals and dielectrics
Full-wave mode
Unstable at DC
Adaptive tetrahedral (volumetric) mesh
Sparse matrix
Simulation time: square
Memory: linear to square
Page 6
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Typical Three Elements of LTCC Design Process
1
Electrical
Design
Physical
Component
Design
nfl
Modify
Layout
Component
Design
2
Design
Requirement
EM - OK?
Yes
No
Feasibility
&
Topology
Yes
More?
No
Ideal Lumped
Passive
Design
3
Physical
Layout
Physical
Design
Full EM
Verification
OK?
Done
Yes
nfl
No
Modify
Layout
Coupling
Analysis
Page 7
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Critical Iterative Design Loops
Design
Requirement
Physical
Component
Design
EM - OK?
Yes
nfl
No
Modify
Layout
1
Component
Level Physical
Design and EM
Simulations
Feasibility
&
Topology
Yes
More?
No
Ideal Lumped
Passive
Design
2
Physical
Layout
Full Layout Level
Physical Design and
EM Simulations
Full EM
Verification
OK?
Done
Yes
nfl
No
Modify
Layout
Coupling
Analysis
Page 8
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Yes
Physical
Component
Design
EM - OK?
More?
Yes
No
nfl
No
Modify
Layout
Component
Level Physical Design
and EM Simulations
Circuit Level
Physical Design
with AMC
Yes
Select AMC
Component
(Design Kit)
Tune/Opt
Component
Parameter
No
More?
Page 9
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
accuracy
automation
Models
generality
Page 10
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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)
Parameters
data
freq.
Page 11
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Advanced Model Composer Technology
Key Technology 1: Adaptive Sample Selection
p 2
freq
freq
p 1
Traditional approach
● uniform sampling
● some regions of design space
oversampling : waste of resource
undersampling : accuracy issue
p 1
p 2
AMC
● adaptive sampling
Patented
technology
● reflective exploration technique
quasi-optimal sampling
only relevant samples selected
Page 12
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Advanced Model Composer Technology
Key Technology 2: Adaptive Model Selection
freq
p 1
p 2
freq
Traditional approach
● local interpolation
● some regions of design space :
over-modeling : ringing
under-modeling : accuracy issue
p 1
p 2
AMC
Patented
technology
● global adaptive modeling
● Forsythe interpolation technique
quasi-optimal model complexity
covers complete design space
Page 13
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Two Plate Capacitor AMC Example
2 Layers parallel plate series capacitor
Vector
Single perturbed parameter
• Variable=EdgeDistFromCenter (10~50mils)
• Results in the area from 20x20 to 100x100 mil 2
Fast model development time
EdgeDistFromCenter
• 0h 2m19s with 512MB RAM and 2GHz processor
PC
Page 14
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
AMC Results
50x50mil
EM Results
75x75mil
Page 15
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
1mm
1mm
Page 16
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 17
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 18
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 19
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

AMC Model Generation 3 Steps (Ex: Helical
Inductor)
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
Page 20
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

AMC Model Generation 3 Steps (Ex: Helical
Inductor)
Step 2: Create Layout Component
• Menu:
– “Momentum (RF)>Component>Create/Update”
• It creates layout look-alike schematic symbol for
schematic
Library Browser
Page 21
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

AMC Model Generation 3 Steps (Ex: Helical
Inductor)
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
Page 22
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 23
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Creating AMC Design Kit (2)
1
Assign the name
of component
By default, AMC design kit is created under the
directory $HOME/hpeesof/amc/design_kit
2 3
Enter the
component
description
Select
Model
4
Finish!
Repeat these processes
with all components that
will go into the design kit.
Page 24
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 25
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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”
Page 26
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Transmission Line Balun
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 Divider
2002 IEEE MTT-S Digest
Jung-Hyun Sung, Dal Ahn
LC Equivalent Network
Page 27
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

LC Balun Final Schematic
High Pass
Low Pass
Resonance at f o
Page 28
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

LC Balun Performance at 2.44GHz
Required Inductance = 4.58nH
Required Capacitance = 0.928pF
Page 29
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 30
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 31
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Completed LC Balun Layout
Component Size
ADS Layout
• 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
3D View
Page 32
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

Complete EM Verification of LC Balun with
Momentum
Page 33
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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
Page 34
A Faster and Effective RF Module/LTCC
Design Flow with AMC
Version 1.0

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Revised: March 27, 2008
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