Sonnet Workshop EuMW 2003

1

• Sonnet Workshop EuMW 2003
• Munich
• Sonnet Software Inc.
• and
• Dr. Mühlhaus Consulting Software GmbH

2
Agenda
Part 1 Introduction to the Sonnet 3D Planar
Electromagnetic (EM) Analysis Suite
Break Part 2 Using Sonnet with AWR Microwave
Office. Using Sonnet with Agilent
ADS. Break Part 3 Recent Advances in Planar
EM Simulation Adaptive Band Synthesis
(ABS) and Conformal Meshing.
3

• Introduction to
• Sonnet Professional
• Release 9
• Dr.-Ing. Michael Reppel
• Dr. Mühlhaus Consulting Software GmbH

4
Sonnet Professional 9 Basic Concepts
5
Field Simulation vs. Circuit Simulation (1)

• Circuit Simulation
• cascading of single models / elements
• advantage very fast
• disadvantage limited to available models,
  limited parameter values

6
Field Simulation vs. Circuit Simulation (2)

• Field Simulation
• no models, no parameter limitation
• arbitrary structures can be analyzed
• advantage more accurate and flexible than
  models
• disadvantagemore complex and slower simulation

7
Field Simulation vs. Circuit Simulation (3)

• Useful Strategy
• combination of circuit and field simulation
• co-simulation of passive and active components
• tuning elements can be added for fast tweaking

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2D, 3D planar Full 3D Simulation








2D

3D

3D Planar


Cross Section
Volume

FlexPDE

Sonnet

Microwave Studio

Quickfield

Momentum

HFSS

LINPAR

Ensemble

Empire




Surface mesh
Volume mesh
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Method of Moments (MoM) (1)

• Step 1 For N subsections, fill NxN matrix with
  couplings between every possible pair of
  subsections.
• Step 2 Invert matrix.

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Method of Moments (MoM) (2)

• Each matrix element is the coupling from one
  subsection to another.
• In other words, the total voltage over the area
  of subsection j due to current over the total
  area of subsection i.

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Method of Moments (MoM) (3)

• Each matrix element requires a 4-D integration
• Integrate twice over (x, y) of the source
  (current carrying) subsection.
• Integrate twice again over (x, y) of the field
  (voltage) subsection.

x
y
x'
y'
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Shielded vs. Open

• Shielded Coupling between subsections is a
  simple sum of sines and cosines.
• 4-D integration is done term by term exactly.
• No numerical integration, very robust and
  accurate.

• Open Requires 4-D numerical integration of
  highly singular kernel for every element in the
  NxN matrix.
• Lacks robustness and accuracy, especially when
  pushing limits.

14
Open Environment

• Difficulty with limit situations like
• Thin dielectric layers (especially more than
  one).
• Dielectric loss (especially silicon).
• Ground plane loss.
• Small subsection size.
• Large numbers of subsections.
• Low frequency.
• Small magnitude S-parameters (noise floor).
• Resonant situations.
• Error from a few percent to unusable data.
• Principle advantage arbitrary subsection size.

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Shielded Environment

• Boundary condition given by closed metallic box.
• Four side walls ideally conducting, cover and
  bottom metallization is arbitrary.
• FFT requires circuit to fall on snap grid.
• Sum of cosines and sines evaluated with FFT
  Fast and accurate. All matrix elements
  calculated to full numerical precision.

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Discretization in 3D planar Method of Moments
solver
All metallization layers must be discretized!
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Discretization vs. Wavelength ? (1)
The discretization must consider the maximum
guided wavelength to avoid high errors
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Discretization vs. Wavelength ? (2)

• Sonnet automatically limits maximum subsection
  size to safe value (if grid resolution allows)
• Default value in Sonnet is safe ?/20

Advanced settings for power users!
19
Discretization of Details

• Some details lt ?/20 are important
• Skin effect edge current enhancement
• High current densities at discontinuities

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Automatic Mesh Generation
Cells are merged to larger subsections, but edges
and corners are detected - required memory is
reduced without losing accuracy.
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Discretization of Arbitrary Shapes

• Discretization of Non-Manhatten shapes is only
  approximate
• Accuracy is not an issue, only efficiency - high
  number of subsections.
• Coarse mesh is ok in many case
• If in doubt, refine mesh for convergence test

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New in Sonnet V9 Conformal Mesh - Efficient Mesh
for Round Polygons
Staircase Mesh 987 MB, 22 min/frequency
Conformal Mesh 10 MB, 35 sec/frequency
Significant reduction of memory requirements for
round spirals analyses
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Conformal Mesh - Staircase Mesh Comparison of
Results (Spiral)
Almost identical results for conformal and
staircase meshing.
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Meander Line with Conformal Mesh
Conformal1104 subs, 6 MB
Staircase 2237 subs, 20 MB
Significant reduction of memory requirements for
round meander lines
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Conformal Mesh - Staircase Mesh Comparison of
Results (Meander)
Almost identical results for conformal and
staircase meshing.
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Choosing the Cell Size

• Compromise between accuracy and speed
• Sonnet does not require numerical integration -
  low noise floor and numerically robust
• Error converges to zero

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The Sonnet Project Editor
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Quick Start Guide
The Quick Start Guide (QSG) appears when you open
the project editor or select Help gt Quick Start
Guide from the project editor main menu. This
guide provides step by step directions in how to
create a circuit geometry in the project editor
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Specifying of Dielectric Layers, Dielectric
Material Library
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Specifying of Metal Types, Metal Type Library
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Specifying of Cell and Box Size
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The Project Editor Tool Box
Reshape move point(s)
Add point
Pointer select
Add donut
Add port
Add rectangular via
Add edge via
Add circular via
Via mode one up / one down / to GND
Draw rectangle with mouse
Draw polygon with mouse
Draw mode metal / brick
Shift mouse click means remain in mode
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Entering the Design and Analysis Frequency Range
Input and Output Ports
Lossy 50 Ohm Line, 0.5mm x 16mm on 0.5mm thick
AlO2
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Memory Estimation and Evaluating the Subsectioning
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Performing an EM Analysis
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Adaptive Band Synthesis (ABS) Sweep

• Provides fine resolution response for an
  arbitrary frequency band - usually develops
  200-400 points
• Adaptively selects minimum number of frequencies
  for full EM simulation
• Internal solver information is used to synthesize
  high-confidence fine model
• Can be used over bandwidths gt 100x

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Evaluating the S-Parameters (50 Ohm Line)
Normalizing Impedance
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Evaluating the S-Parameters (Non-50 Ohm Line)
Normalizing Impedance
39
Evaluating the Current Density Distribution
40
Sonnet Professional 9 Selected Topics
41
The Port Concept of Sonnet

• All ports in Sonnet are two-terminal devices
• The port terminals can be connected between two
  conducting elements metal polygons, box walls,
  vias
• The port type is determined by where the
  terminals are connected to.

Equivalent circuit of a Sonnet port
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Standard Box-Wall Ports
A standard box-wall port is a grounded port, with
one terminal attached to a polygon edge
coincident with a box wall and the second
terminal attached to ground.
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Ungrounded-Internal Ports
A standard ungrounded-internal port is located in
the interior of a circuit and has its two
terminals connected between abutted metal
polygons.
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Via Ports
A via port has one terminal connected to a
polygon on a given circuit level and the other
terminal connected to a second polygon on a
circuit level above the first polygon.
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Automatic-Grounded Ports
An automatic-grounded port is a special type of
port used in the interior of a circuit. This port
type has one terminal attached to the edge of a
metal polygon located inside the box and the
other terminal attached to the ground plane
through all intervening dielectric layers.
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Ports with Duplicate Numbers
Ports with identical port numbers are
electrically connected together push-push / even
mode ports.
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Ports with Negative Numbers(Differential Ports)
The total current going into all the positive
ports with the same port number is set equal to
the total current going out of all the ports with
that same negative port number push-pull / odd
mode ports.
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Ports with Negative Numbers(Coplanar Waveguide
Ports)
Coplanar lines can be represented by push-pull
ports
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Parameterization of Geometries
50
Evaluating Parameter Sweep Results
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Optimization of Geometries
52
Netlist Project Analysis
A netlist project contains a netlist which
consists of one or more networks with elements
connected together.
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Cascading S-, Y- and Z-Parameter Data Files
The two-port S-parameters contained in file
att_res16.s2p are cascaded to obtain an overall
set of two-port S-parameters.
54
Inserting Lumped Elements or Measurements into a
Geometry (1)
With the help of internal ports lumped elements
or SNP files of measurements can be included in
the analysis.
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Inserting Lumped Elements or Measurements into a
Geometry (2)
Using automatic-grounded ports The geometry file
contains sets of auto-grounded ports placed at
locations where modeled elements will eventually
be inserted.
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Inserting Lumped Elements or Measurements into a
Geometry (3)
Using ungrounded-internal ports The geometry
file contains ungrounded-internal ports placed at
locations where modeled elements will eventually
be inserted.
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Inserting Lumped Elements or Measurements into a
Geometry (4)
Using ungrounded-internal ports Ungrounded-intern
al ports do not have access to ground. Therefore,
only 1-port elements or 1-port networks may be
connected across ungrounded-internal ports (e.g.
resistors, capacitors, and inductors).
Using automatic-grounded ports Automatic-grounded
ports do have access to ground. Therefore,
N-port elements may be connected across a set of
automatic-grounded ports (e.g. transmission
lines).
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Inserting Lumped Elements or Measurements into a
Geometry (5)
For expert users only including N-Port Elements
using ungrounded-internal ports Ungrounded-intern
al ports do not have access to ground. However, a
common reference can be used.
common reference
Note Port 3 is negative, Port 4 is positive !!!
SMD pads
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Inserting Lumped Elements or Measurements into a
Geometry (6)
Note for expert users if a set of
ungrounded-internal ports with a common reference
is used, make sure the polarity of each port is
correct. This means that all ports must be
connected with the same terminal at the reference
metalization!
-
-


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Using Internal Ports for Circuit Tuning (1)
An ungrounded internal port can be used to tweak
the element value of an inductor.
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Using Internal Ports for Circuit Tuning (2)
Results for inductor tuning range -1nH to 1nH
(L1 at port 3)
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Using Internal Ports for Circuit Tuning (3)
A via port can be used to tweak the element value
of a parallel plate capacitor.
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Using Internal Ports for Circuit Tuning (4)
Results for capacitor tuning range -0.5pF to
0.5pF (C1 at port 3)
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De-embedding (1)

• Each port in a circuit introduces a discontinuity
  into the analysis. De-embedding removes this port
  discontinuity from the analysis results.
• With de-embedding, reference planes may be
  shifted.
• Within the de-embedding process the
  characteristic impedance Z0 and the effective
  dielectric constant Eeff of the feeding
  transmission line are determined.
• The de-embedding option is switched on by
  default, but may be switched off.

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De-embedding (2)

• Standard box-wall ports, ungrounded internal
  ports and automatic-grounded ports can be
  de-embedded. In case of automatic-grounded ports
  the length of the via to ground is removed from
  the analysis result.
• Via ports can not be de-embedded.

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De-embedding Shifting Reference Planes
(1)
Transmission Lines
Port discontinuities and transmission lines at
the left and right are removed from the em
analysis results by enabling de-embedding.
Transmission Lines
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De-embedding Shifting Reference Planes
(2)

• Reference planes may be specified for standard
  box-wall ports and automatic-grounded ports
• Reference planes can not be specified for
  ungrounded internal ports and via ports
• Reference planes can be specified for coupled
  transmission lines. The coupling between the
  transmission lines is accounted for and removed.

68
De-embedding Benchmark Zero Length Coupled
Lines
The coupling between these transmission lines is
about -20dB. The reference planes are so
specified that the resulting coupling length is
zero. The de-embedding process removes the
coupling between the lines completely.
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De-embedding Benchmark Results Zero Length
Coupled Lines
The de-embedding process removes the coupling
between the lines completely (noise floor level).
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De-embedding Guidelines (1)

• De-embedding Without Reference Planes
• De-embedding does not require reference planes.
  Reference planes are optional for all standard
  box-wall and automatic-grounded ports.
• Reference Plane Length Minimums
• If the reference plane or calibration standard is
  very short relative to the substrate thickness or
  the width of the transmission line, em may
  generate poor de-embedded results.

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De-embedding Guidelines (2)

• Reference Plane Length Minimums
• The port is too close to the device under test
  (DUT)
• The first calibration standard is too short.

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De-embedding Guidelines (3)

• Reference Plane Lengths at Multiples of a Half-
  Wavelength
• Eeff and Z0 cannot be calculated when the length
  of the reference plane or calibration standard is
  an integral multiple of a half wavelength.
• Reference Plane Lengths Greater than One
  Wavelength
• If the length of the reference plane or
  calibration standard is more than one wavelength,
  incorrect Eeff results might be seen. However,
  the S-parameters are still completely valid.

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De-embedding Guidelines (4)

• Non-Physical S-Parameters (1)
• Extending the reference planes beyond a
  discontinuity in the circuit may result in
  non-physical S-parameters.

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De-embedding Guidelines (5)

• Non-Physical S-Parameters (2)
• Box Resonances A structure which is inside a
  resonant cavity can not be de-embedded
  correctly.
• Higher Order Transmission Line Modes The
  de-embedding assumes that there is only one mode
  propagating on the connecting transmission line,
  usually the fundamental quasi-TEM mode. If higher
  order modes are propagating, the de-embedded
  results are not valid. The same is true for
  actual, physical, measurements.

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Vias (1)

• Vias can be used to connect metalization between
  any substrate or dielectric layer. Thus, ems
  vias can be used in modeling airbridges, spiral
  inductors, wire bonds and probes as well as the
  standard ground via.
• Ems vias use a uniform distribution of current
  along their height and thus are not intended to
  be used to model resonant length vertical
  structures.
• There are basically two types of vias edge and
  polygon. The via polygons can be rectangles,
  circles or any arbitrary shape.

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Vias (2)
Examples of via polygons The shape drawn by the
user appears in black. The actual via metal is
shown by the fill pattern which is the video
reverse of the metal pattern. Since current
travels on the surface of a via, the middle of
the via is hollow, filled with the dielectric
material of the dielectric layer that the via
traverses.
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Multi-Layer Vias
A via may traverses more than one dielectric
layer. It can originate on any level and end on
any level. The via is automatically drawn on each
level it traverses.
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Metalization Loss (1)
Metalization losses may be assigned to circuit
metal, top cover and ground plane. Sidewalls are
always assumed to be perfect conductors. The
Sonnet model of metal loss uses the concept of
surface impedance, measured in Ohms/sq. This
concept allows planar EM simulators to model real
3-dimensional metal in two dimensions.
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Metalization Loss (2)
In most cases the normal metal type may be
chosen. The user determines the loss using the
bulk conductivity, the metal thickness and the
current ratio. The current ratio is the ratio of
the current flowing on the top of the metal to
the current flowing on the bottom of the metal.
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Dielectric Loss

• The loss equation can be expressed in terms of an
  overall loss tangent

Values entered by user

• The loss equation can also be expressed in terms
  of an overall conductivity

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Thick Metal Analysis
The thickness of a metalization can be accounted
for by modeling both surfaces with a zero
thickness metalization sheet. Additional interior
sheets can refine the model further.
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Automatic Thick Metal Analysis in Sonnet V9
The influence of thick metalization can easily be
analyzed without rebuilding the simulation model.
83
Dielectric Bricks
A dielectric brick is a solid volume of
dielectric material embedded within a circuit
layer. Such a brick can be added anywhere in the
circuit.
84
Spice Lumped Model Synthesis
The Spice lumped model synthesis takes the
results of the electromagnetic analysis of a
circuit and synthesizes a lumped model of
inductors, capacitors, resistors and mutual
inductors. This Spice generation capability is
intended for any circuit which is small with
respect to the wavelength of the highest
frequency of excitation.
85
Antennas and Radiation
Radiation can be simulated by including a lossy
top cover and by placing the sidewalls far from
the radiator. The top cover should be placed one
half wavelengths from the radiator.
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HTML Auto Documentation in V9
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Sonnet Professional 9 Applications
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Application Example 1 Superconducting Microstrip
Filter (1)
Circuit simulator result with modeled elements
Specs
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Application Example 1 Superconducting Microstrip
Filter (2)
Field simulator result (Sonnet em with ABS)
90
Application Example 1 Superconducting Microstrip
Filter (3)
Measurement vs. Sonnet field simulation
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Application Example 2 Stripline Filter
The em analysis of the filter requires only 4
frequency points with ABS sweep!
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Application Example 3 Interdigital Microstrip
Filter
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Application Example 4 Stripline to Microstrip
Transition
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Application Example 5Coax Fed Patch Antenna
(1)
Analyzed current density at center frequency
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Application Example 5Coax Fed Patch Antenna
(2)
Polar plot of the antenna pattern
(theta-cuts). Blue Phi 0 deg Red Phi 90 deg
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Application Example 6 868 MHz Loop Antenna
(1)
Y
X
Sonnet Model
Hardware Layout on FR4
Analyzed current density at center frequency
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Application Example 6 868 MHz Loop Antenna
(2)
Blue Theta-Cut, Phi0deg
Red Theta-Cut, Phi90deg
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Application Example 7 Spiral Inductor
(Motorola) (1)
9.25-turn Circular Spiral Inductor on 100 um
Silicon (step-graded conductivity in
substrate) 5 insulating layers between 1 um and
3 um 1-10 GHz measured 45 mins. total for 300
data point sweep (thick metal modeled) 2.5GHz
Pentium 4 Notebook PC Data and design courtesy
of Motorola SPS/WISD
99
Application Example 7 Spiral Inductor
(Motorola) (2)
100
Application Example 8 LTCC Bluetooth Filter
LTCC Module (7-layer) design suitable for
Bluetooth and similar applications
Design and measurements courtesy of National
Semiconductor Corp.
101
Application Example 9LTCC Multi-Layer Diplexer
102
Application Example 10 Motorola LTCC Filter