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Keysight EEsof EDA
EMPro
3D Electromagnetic Modeling
and Simulation Environment Integrated
with your ADS Design Flow
Application Note
Introduction
Electromagnetic Professional (EMPro) is a 3D modeling and simulation environment for analyzing
the 3D electromagnetic (EM) effects of high-speed and RF/microwave components. EMPro features
a modern design, simulation and analysis environment, high capacity time- and frequency-domain
simulation technologies and integration with ADS, the industry's leading RF/microwave and high-
speed design environment.
Keysight EM Solution Overview
EMPro delivers the following key capabilities:
Modern, eficient 3D solid modeling environment
EMPro provides the flexibility of drawing arbitrary 3D structures and the
convenience of importing existing CAD files. You can create 3D shapes, add
material properties, set up simulations, and view results--all within the EMPro
environment.
Time- and frequency-domain simulation technology
3D structures can be analyzed in EMPro using the same FEM simulator
available in ADS. FEM is a frequency-domain technology widely used for RF/
microwave applications. For electrically large problems, such as antennas
and some signal integrity analyses, the finite difference time domain (FDTD)
simulator can be used.
Integration with ADS
Parameterized 3D components can be created in EMPro and placed in a layout
design in ADS. The 3D FEM simulator in ADS can then be used to simulate the
combination of the 2D layout and the 3D EM component.
EMPro Environment ADS Platform
Parameterized
EM components
from EMPro
Layout objects
from ADS
FDTD simulator FEM simulator Momentum simulator
Finite difference time domain Finite element method Method of moments
Figure 1. Keysight provides multiple EM simulation technologies integrated with the ADS design low.
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EMPro Simulation Capabilities
There are several different technical approaches to EM simulation, each with their own advantages in certain application
areas. The most established 3D EM simulation technologies are FEM and FDTD. Both of these technologies are available
in EMPro.
Finite element method
FEM is a frequency-domain technique that can handle arbitrary shaped
structures such as bondwires, conical shape vias and solder balls/bumps where
z-dimensional changes appear in the structure. FEM solvers can also simulate
dielectric bricks or finite-size substrates.
FEM is based on volumetric meshing where the full problem space is divided
into thousands of smaller regions and represents the field in each sub-region
(element) with a local function. The geometric model is automatically divided
into a large number of tetrahedra, where a single tetrahedron is formed by four
equilateral triangles. This collection of tetrahedra is referred to as the finite
element mesh. The Keysight Technologies, Inc. FEM simulator includes both
direct and iterative solvers, and both linear and quadratic basis functions, to
solve a broad range of problems. The same FEM simulator is available in both
EMPro and ADS. EMPro supports remote simulation and distributed frequency
sweeps for FEM.
Finite difference time domain
As with FEM, the FDTD method is based on volumetric sampling of the electric
and magnetic fields throughout the complete space. Whereas FEM meshes
consist of tetrahedral cells, FDTD meshes are typically built from rectangular
(Yee) cells. The FDTD method updates the field values while stepping through
time, following the electromagnetic waves as they propagate through the
structure. As a result, a single FDTD simulation can provide data over an ultra-
wide frequency range.
Because of its simple, robust nature and its ability to incorporate a broad range
of linear and nonlinear materials and devices, FDTD is used to study a wide
range of applications, including: antenna design, microwave circuits, bio/EM
effects, EMC/EMI problems, and photonics. FDTD is an inherently parallel
method and therefore lends itself very well to the processing capabilities of the
most recent advances in CPU (general-purpose processors) and GPU (graphics
processors) hardware. EMPro also supports remote simulation and distributed
port simulations for FDTD.
Table 1. Summary comparison of FEM versus FDTD
FEM FDTD
Frequency domain method Time domain method
Tetrahedral mesh cells Rectangular mesh cells
Good for high-Q structures Good for broadband applications, physical transitions
Fast for multi-port simulations Each port requires additional simulation
Based on solving matrix equations; best for electrically small Based on iterative time stepping; less memory intensive for
problems electrically large problems
Multi-threaded; problems can be divided and run in parallel on Highly multi-threaded; problems can be divided and run in
multi-core CPUs parallel on multi-core CPUs and on large GPU cards
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Typical EMPro Applications
IC packages
The performance of an RFIC, monolithic microwave integrated circuits (MMIC),
high-speed IC, or system-in-package (SIP) is directly impacted by the effects
of packaging, including wire bonds and solder balls/bumps. Traditionally,
designers had to draw and analyze packages in a separate, 3D EM tool and then
laboriously import the results back to the IC or SIP circuit-design environment
for a combined analysis. With EMPro, you can efficiently create 3D package
structures that can be combined with 2D circuit layouts in ADS. This allows
co-design of the IC, package, laminate, and module with circuit simulation and
3D EM simulation in a streamlined design flow.
Multi-layer RF modules
RF modules typically are constructed from multi-layer ceramic or laminate
dielectric material with embedded RF passive components between the layers.
Such dielectric brick structures cannot be accurately solved by planar EM
simulators, which assume infinite dielectric layers and do not account for edge
proximity fringing. The embedded RF components are drawn by RF circuit layout
macros which would be very time consuming to reproduce in a standalone 3D
EM tool. Full 3D EM simulation integrated within the circuit design flow is the
ideal solution for these applications.
RF components
RF board designs include 3D components and connectors that need to be
characterized to high frequencies. Components such as resonators are sensitive
to interactions with the surrounding PC board traces and vias. Such 3D
components can be created and simulated in EMPro and then combined with a
board layout in ADS for complete 3D EM simulation.
Aerospace/Defense
FDTD simulation has extremely high capacity and can handle large
problems found in aerospace/defense applications. For example, FDTD can be
used to optimize antenna placement in aircraft and perform Radar Cross Section
analysis.
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Typical EMPro Applications (continued)
PCB Design
With data rates increasing, PCB traces must now be analyzed as RF
transmission lines. 3D EM technologies complement 3D planar simulators such
as Keysight Momentum for high speed signal integrity analysis, EMI/EMC, and
PCB interfaces to connectors and packages.
High-speed connectors
High-speed connector types such as SATA and HDMI now support Gbits/s data
throughput. High frequency S-parameter models of connectors can be generated
in EMPro and cross-verified with both the FEM and FDTD simulators to give
designers twice the confidence in 3D EM simulation accuracy. The models can
then be included in an ADS design kit that can be distributed and installed into
ADS as a connector library for use in signal-integrity analysis and design of
high-speed serial channels.
Handset antennas
A critical design task in the development of cellular and networking products
is maximizing antenna performance while minimizing antenna size. EMPro can
simulate the antenna in realistic surroundings, including the phone components,
housing and even the human hand and head. Compliance testing can also be
performed, such as specific absorption ratio (SAR) and hearing aid compatibility
(HAC).
EMI/EMC Analysis
With more electronics being integrated into smaller packages, EMI problems
are quickly becoming a leading cause of new product delays. EMPro allows
engineers to simulate the radiated emissions of electronic circuits and
components and then determine whether these emissions are within levels
specified by common electromagnetic compatibility (EMC) standards, such as
FCC Part 15, CISPR 22 and MIL-STD-461F and ensure that their designs are
compliant.
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EMPro Environment Overview
Geometry modeling