Belforte multiboard conducted_issues

EMC simulation of multiboard

electronic systems for conducted

issues

Mr O. THENOZ

Toulouse - France

Mr L. DREUX

Suresnes - France

Mr E. LEROUX

Torino - Italy

Mrs F. JOUACHIM

Les Ulis - France

This document is the property of AEROSPATIALE MATRA CCR ; no part of it shall be reproduced and / or transmitted without the express prior written authorisation of AEROSPATIALE MATRA CCR and its contents shall not be disclosed

© - AEROSPATIALE MATRA CCR - 2000 2

European project OMEGA

This work is the result of an ESD Best

Practice project (contract nr 28599) from

the European Community

OMEGA (Optimisation of Multiboard

systems under EMC Guidelines for

Avionics)

Partners :

Aerospatiale Matra AIRBUS as end user

Aerospatiale Matra CCR as research centre

HDT as software developper

Zuken Redac as tool vendor



Objectives and challenges

Objectives :

Improve an EMC software solution, based on

aeronautical needs

Validate this simulation software on avionics

applications

Introduce this solution in the design industrial

process

Challenges :

reduce costs and time to market by :

taken EMC constraint as early as possible in the design

cycle

avoiding redesign cycles and reducing number of tests



EMC constraints on PCB

Signal integrity :

propagation on boards (delay, reflection, …)

crosstalk between nets

simultaneous switching noise (SSN)

Emission :

conducted and radiated emission

Susceptibility :

conducted and radiated susceptibility

OMEGA focused on signal integrity

applied to multiboard equipment



EMC in the design process

Placement EMC

analysis

Layout EMC

analysis

Technological choices

EM environment

specification Schematic EMC

analysis

functional

design

placement

Spécification Detailed design Preliminary

design routing

Validation and

qualification

Tests Obsolescence

management

OMEGA

Evolution



EMC modelling : today's solutions

Signal integrity simulators :

based on transmission lines algorithm

using either proprietary or IBIS standard

components models

linked to electronic CAD tools

EMC modelling - emissions :

full 3D solutions : not adapted to large PCB

approximated methods : some phenomena

not well addressed

EMC modelling - susceptibility :

no solutions available



Avionics : user requirements

All equipment are multiboard equipment

Complexity of boards : at least 12 layers -

ground and power planes

User requirements :

strong integration in the CAD flow

short simulation time

link with functional simulator

cover all signal integrity aspects

automatic post processing highlighting the

potential problems



Tools improvement

Based on PRESTOTM _MBMS (standing for

MultiBoard MultiSignal) prototype tool from

HDT signal integrity and EMC analysis

environment :

Allowing multiboard simulation

Allowing SSN simulation with copper planes

Improving the mask management for automatic

post processing

Developing a link with functional simulation

(QUICKSIM interface)

Allowing management of bidirectional

component pins



Data flow (1/2) : Single board enhancement

CAD EXTRACTOR

POWER

PLANES

SIGHTS

(display of results)

RADIATED EMISSION

PREDICTION

WHAT-IF ANALYSIS

PRESTO_MBMS 1.0

CORE INCLUDING

SSN AND

CROSSTALK

ANALYSIS

SPRINT

SIMULATION

QUICKSIM

INTERFACE

USER INTERFACE

MODEL LIBRARY

BIDIR

MANAGEMENT

NEW MASK

MANAGEMENT

Board N input data

Existing PRESTO_MBMS ver. 1.0 flow

User Requirements



Data flow (2/2) : Multiboard enhancement

SIGHTS

(display of results)

PRESTO_MBMS 1.1

CORE INCLUDING SSN

AND CROSSTALK

ANALYSIS

SPRINT

SIMULATION

MODEL LIBRARY

Board 1 input data

for

PRESTO_MBMS

1.1 core

Board 2 input data

for

PRESTO_MBMS

1.1 core

Board N input data

for

PRESTO_MBMS

1.1 core

Multiboard user interfcae

Existing PRESTO_MBMS ver. 1.0 flow

User Requirements



Core engine : key features

Integration into VISULATM CAD tool

Fast field solver to compute transmission line

parameters (lossy models)

Simulator based on digital signal processing

techniques :

computation of signals on each nets

simultaneously, with constant time step simulation

accurate and quick algorithm

linear evolution of simulation time regarding number of

nets

Four pins components models allowing SSN

simulation



Multiboard development

Importation of mother board and daughter

boards layout from VISULA

Definition of the interconnections between

boards in a separate file :

short circuits

connector model (in terms of RLC circuits

multiboard signal integrity simulation

functionality identical to those available on

single boards :

selection of nets

definition of crosstalk situations

SSN modelling capability



SSN improvement (1/2)

Copper areas (supply or ground planes) are

meshed with a regular grid of lossy

transmission lines :

ability of taken into account the common

impedance path between the different supply or

ground pins of the components

Development of a mesh algorithm :

areas are surrounded by a rectangle, divided into

regular square meshes proportional to the time

step simulation

transmission lines parameters are computed on

each elementary cell of the mesh



SSN improvement (2/2)

Development of a mesh algorithm :

a percentage of filling in each cell is taken into

account

Illustration of the process : 0%88%100%

dstep

micro-grid linked to tstep

grid on which is built TL

grid_step

Zoom



Case study description

Validations performed on a computer board :

a central process unit board (CPU) :

designed with a Pentium microprocessor

management of memory, slave board and resources

access

an input/output board (I/O)

a backplane connecting the above boards

Comparison between measurements and

simulations on different signals :

memory access on the CPU

control signal between the I/O and CPU via the

backplane



Case study validation (1/2)

Simulation Measure



Case study validation (2/2)

Simulation Measure



Methodology

Simulation tool is inserted into the design

flow :

Engineering phase

CAD/PCB phase

Design phases

EMC IC models :

creation

importation

Library management

Break points

CAD extraction EMC analysis

Validation



Conclusions

Large system of nets (especially on

multiboard) can be simultaneously taken into

account with simulation time compatible to

industrial constraint

All conducted EMC effects are simulated :

Real stimuli could be handled

Copper areas (ground and supply planes) are

modelled

Skin effects in conductors are taken into account

The tool is validated and integrated in the

CAD design flow of the user



Future work

Efforts have to be made on IC models

(IBIS standards or proprietary models)

Numerical methods to handle EMC effects

(emission, susceptibility) have to be

developed

A deeper integration of the EMC tools in

the CAD flow has to be evaluated :

concurrent engineering, introduction of EMC

simulation earlier in the design phases

partially routed board simulation associated

to what if analysis and back annotation

Belforte multiboard conducted_issues

Technology

Transcript of Belforte multiboard conducted_issues