05 Full System EMI EMC Methodology

8/10/2019 05 Full System EMI EMC Methodology

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How to model EMIHow to model EMIusingusing AnsoftAnsoft HighHigh

Frequency ToolsFrequency Tools

How to model EMIHow to model EMIusingusing AnsoftAnsoft HighHigh

Frequency ToolsFrequency Tools

2010 ANSYS, Inc. All rights reserved. 1 2010 ANSYS Regional Conferences



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EMI the result of undesired signals interfering withsystem performance.

Examples:

Cross-talk between digital and analog signals on a PCB

Noise on power and ground planes due to switching SSN

EMI Definition


Mobile phone interference with television, radio, etc.

Car radio interference due to automobile electronics.

Various mechanisms can contribute to the problem

including radiation, magnetic induction, conduction etc.


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EMI - Source Basics

Intentional Sources

Expected or easily predicted sources for radiation

Emissions from intentional signals include

loop-mode sources


Unintentional Sources (more than 90% of EMI*) Unexpected or surprise sources

Emissions from unintentional signals include

common-mode noise sources,

crosstalk coupling to I/O traces (PCB, PKG, and IC levels),

power planes, and other board structures.

*Reference from PCB Design for Real-World EMI Control Bruce Archambeault


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Circulating or loop currents can act as antennas

Radiation efficienc of above antenna is determined b loo size

EMI Radiation Basics

Is

Is Is


Injecting a realistic current excitation into a PCB simulation can easilypredict radiation and emission spectrum

Proper de-coupling capacitor placement, power integrity design, andenclosures can help mitigate EMI.

Full System EMI analysis therefore requires a simulation strategy thatincludes realistic sources, realistic PCBs, 3D enclosure.


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State of the art EMI/EMC simulation method that

utilizes the best in class tools

incorporates physical board layouts

uses real world transient signals

takes into account full 3D enclosures

What is the Full System

EMI/EMC Methodology


seamlessly combines frequency and time domain simulationtools to predict EMI


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Board analysis

SIwave Full 3D enclosure

HFSS

What are the tools needed


,

DesignerSI

CAD links

AnsoftLinks

Productivity enhancers

Distributed solve option


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Pre or Post-layout analysis tool

Solves

Entire multi-layer Printed Circuit Board(PCB)

Entire leaded Integrated Circuit (IC)Package

Uses

2D FEM for Power/Ground plane

structures 2D Transmission line MoM solver for

traces

3D quasi-static solutions for transition

What is SIwave


, , .

Applications

PCB signal integrity calculation

PCB power delivery characterization

De-coupling capacitor locationevaluation

Circuit model generation

DC current and voltage distribution onPCB


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Premier 3D Electromagnetic designtool

Solves

Any arbitrary 3D structure

Uses

Full Wave Finite Element Method (FEM)

Applications

Antennas

EMI/EMC

What is HFSS


Satellite equipment

Integrated circuit packages

Connectors

Radar equipment

Routers

Wireless communication gear

And more


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Integrates ANSYS HF tools into aseamless system simulation

Solves

Time / frequency circuits and systems

Uses

State Space or convolution

time domain spice solver Harmonic Balance

frequency domain solver

2D / 3D Method of Moment solver

What is Designer SI


pp ca ons

Time and / or frequency domain circuitanalysis

Signal Integrity

Antenna Arrays

RF IC simulation


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What is DSO

An add-on option for Optimetrics

which Takes advantage of high-performance

computing resources

Distributes frequency sweeps and certain


Optimetrics simulations across multipleprocessors and/or computers

Performs simulations in parallel rather thansequentially

Highly scalable near-linear improvement in

compute time


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1. Import PCB layout into Ansoft Links or SIwave

2. Perform analysis of PCB in SIwave

3. Dynamically link SIwave results into Ansoft Designer4. Attach drivers and receivers in Designer to linked SIwave model

5. Perform a time/frequency domain analysis of entire system inDesigner

What are the steps


6. Push voltage/excitation levels back to SIwave7. Dynamically link the SIwave model into HFSS

8. Solve the full system in HFSS


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Full System EMI Analysis

8 Layer PCB

Single long clock trace PCB is located inside PC case

Determine EMI spectrum of clock trace on PCB only

Determine EMI s ectrum of clock trace on PCB when PCB is inside

A Simple Example


enclosure


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Step 1. Import PCB layout into

AnsoftLinks or SIwave

Use Ansoft Links to import the PCB layoutand associated components from 3rd party

layout programs


Design export from Cadence,Mentor, Synopsis, Zuken tools

Clean-up, de-feature and/or choosecritical nets to be exported to 3D simulators

SIwaveAnalysis ofcomplete PCB


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Step 2. Perform analysis of

PCB in SIwave

2a) Assign ports to all relevantPCB traces in SIwave

SIwave Port


2b) Select Simulationtype and frequencyrange


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Step 3. Dynamically link SIwave

model into Ansoft Designer SI

From Project menu selectadd SIwave model

Browse to file location and

select appropriate SIwave model

The linked model will be added



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Create EMI circuit model in

Designer SI

In Project tab from theModel Folder select and dragSIwave model into schematic


IBIS buffer Folder select anddrag IBIS drivers andreceivers model intoschematic

In Components select other

needed components such asvoltage sources and probes


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Setup Transient Simulation

and plot results

0.00 3.50

1.08 1.10 1.12 1.14 1.16 1.18Time [us]

0.00

0.50

1.00

1.50

2.00

2.50

Y1[V]

Ansoft LLC Nexxim1Rcvr Pattern

Curve Info

V(Rcvr)

Transient

2010 ANSYS, Inc. All rights reserved. 17 2010 ANSYS Regional Conferences0.00 50.00 100.00 150.00 200.0 0 250.0 0 300.0 0 350.0 0 400.00 450.00 500.0 0

Spectrum [MHz]

-100.00

-80.00

-60.00

-40.00

-20.00

-0.00

20.00

dB(V(Rcvr))

Ansoft LLC Nexxim1Frequency_Spectrum

m1

m2

m3

m4

m5

m6

m7

m8

m9

m10 m11

m12

m13

m14

Name X

Curve Info

dB(V(Rcvr))

Driver Receiver

In Project tabselect Analysisselect Transient AnalysisEnter Stop time and

Step sizeThen Solve

After simulation finishesUsers can plot time domainwaveforms andfrequency spectrum results


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Push Excitations back to

SIwave

After Solution finishesselect Linked Model

Then right mouse button click

Select Push Excitations

Then in thePush Excitations Information screenselectSolution, start and stop time,


armon c num er an w n ow ng

type

Magnitude and phase ofvoltages at pins P1 and P2will be pushed to SIwave


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Plotting EMI in SIwave


Using the pushed Excitations

The near fields can also beplotted on the PCB

Using the Pushed Excitations

Far Fields can be plotted.Maximum E fields at a distance can alsobe plotted as shown above in order tomimic a regulatory emission plot


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Dynamically link the SIwave

model into HFSS

4) Siwave

results aredynamically

linked into

HFSS model

Set-up HFSS simulation of enclosure

Instead of ports useIncident Near Field Excitation

HFSS will use the fields from SIwaveas an excitation inside the HFSS model


In the Incident wave setup you will specifyLocation of the source fields by

Specifying a translation andRotation of source fields

Will also need to specifythe path to the linked model


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Finishing the Full System EMI

Simulation

Once simulation is setup andsolved can plot Fields and Far

field plotsAs well as all other HFSS results

Maximum E Field at 3m distance


1.00 10.00 100.00 1000.00Freq [MHz]

-90.00

-80.00

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

10.00

20.00

3mS

phere(dBuVolts)

Ansoft Corporation HFSSModel1XY Plot 1

Curve Info

3M Sphere Max EField values

Setup1 : Sweep1

E Field on surface of Enclosure


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SIWave is used to extract electromagnetic N-port model of

Driver-Receiver Communication channel

Data BUS, Clock,

Data Strobe

Power net

A More Complex EMI Example


This physical model include all possible coupling that exist betweennets

Signal-to-Signal

Signal-to-PWR/GND

PWRi-to-PWRj

Predict EMI from data channel


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The SIwave Model

Driver-Receiver Communication channel


SIwave data channel simulation includes 16 Data lines 2 Strobe lines 2 clock lines Power and Ground nets All on multiple layers

Full Board SIwave modelData channel close-up


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The Designer Model


Drivers

Receivers


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The Designer Results

Solve Designer Transient circuit


Push Excitations back to SIwave

Designer Transient Spectral Results


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SIwave Results

Max E field at 1m (dBuV/m)In both the horizontal andvertical planes



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Results Comparison

SIwave to Measurement



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It has been shown that creating a full system EMI simulation ispossible by using the combination of Ansoft Designer, SIwave,

and HFSS.

The creation of a full system EMI simulation is a straightforward

Final Thoughts


,

signals, and enclosures.

As seen in this presentation, using this full system EMImethodology, it is possible to produce simulation results that

compare very well with measurement.

Documents

05 Full System EMI EMC Methodology