Adv. Radio Sci., 9, 111–116, 2011
www.adv-radio-sci.net/9/111/2011/
doi:10.5194/ars-9-111-2011
© Author(s) 2011. CC Attribution 3.0 License.
Advances in
Radio Science
Modeling automotive FlexRay transceivers for signal integrity and
EMC simulations
H. Günther, U. Hilger, and S. Frei
Technische Universität Dortmund, Dortmund, Germany
Abstract. Automotive bus systems like FlexRay or CAN
transmit safety critical data. To ensure correct functionality
under all circumstances, extensive investigations about signal
integrity and EMC have to be performed. To be able to use
simulation in this validation process, suitable models for the
components of the bus systems have to be developed. This
paper shows how a combined transceiver model for signal
integrity and EMC investigations can be created. The model
shows good results in comparison to measurement data.
with output characteristics while EMC models reflect the input behaviour of a device. However, intersections between
those two fields exist and can be used to create a transceiver
model to reflect both behaviours. As result the combined
model is able to reflect the signal integrity behaviour of a
real transceiver device in a wide range of input voltage and
under electromagnetic disturbances and considers operation
thresholds which limit normal operation ranges.
2
1
Introduction
2.1
Automotive bus systems are used to connect control units,
intelligent sensors and actors in vehicles. From economical
point of view extended cable networks are desirable. Systems are often operated close to their specification limits. To
provide safety critical applications under these circumstances
or electromagnetic disturbances, the functionality of a bus
system must be ensured with sophisticated methods.
An approach to detect problematic behaviour and its
causes is the computational investigation of the transmitted
signal quality (signal integrity) of the physical layer of the
bus system. Models for any component of a bus system have
to be developed. Accuracy of models and methods has to be
qualified by measurements with realistic systems.
To ensure a high immunity against electromagnetic disturbances, the transceivers should be qualified with special RF
immunity tests. EMC simulations may help to investigate
possibly critical cases. Therefore accurate EMC behavioural
models are needed (Hilger et al., 2010).
This paper shows the capabilities of bus system signal integrity and EMC simulation and focuses on modelling of
the transceiver device. SI transceiver models mainly deal
Correspondence to: H. Günther
(harald.guenther@tu-dortmund.de)
Simulation models for SI and EMC
Signal integrity simulation model of FlexRay
transceiver
A FlexRay transceiver consists of general functional parts,
e.g. for sending, receiving, and decoding data. Figure 1
shows a general structure of interconnection between those
parts, which is the basis for the transceiver signal integrity
simulation model (Günther et al., 2010).
For signal integrity investigations the most important part
of the bus transceiver model is the output driver. The model is
based on a physical approach which is shown schematically
in Fig. 2. The three possible bus levels belonging to the internal transceiver states idle, active low and active high are realized by interconnection of two MOSFET transistors. They
work as controlled switches based on the MOSFET equations
and connect the bus output pin with ground or supply voltage,
depending on the state of the transceiver. The adaption of the
switching behavior and of the bus levels is done with a differentiable control function and the series connection of two
diodes. When idle, both transistors are in high impedance
mode and the transceiver is ready for signal reception. An
additional ohmic voltage divider is used to model the correct
impedance behavior in this case and provide the bias voltage.
To ensure correct behavior in different load conditions and to
model the slope correctly, capacitive effects of the transceiver
device are modelled using output capacitors.
Published by Copernicus Publications on behalf of the URSI Landesausschuss in der Bundesrepublik Deutschland e.V.
bus
ned
ons
n to
A FlexRay transceiver consists of general functional parts,
e.g. for sending, receiving, and decoding data. Figure 1 shows
a general structure of interconnection between those parts,
which
simulation
112is the basis for the transceiver
H. Günthersignal
et al.:integrity
Modeling
automotive FlexRay transceivers for signal integrity and EMC simulations
model [1].
correctly, capacitive effects
Vccof the transceiver device are
capacitive effects of the transceiver device are
led slope
using correctly,
output capacitors.
Voltage
nits, modelled using output capacitors.
Regulator
ical
ems
Vcc
Vcc
vide
or
Bus Driver Bus
TxD_del
TxDDriver TxD
tem
Delay PMOS
PMOS
uses
gnal
bus TxEN
o be State
logic
be TxD
RxD
Vcc_reg
2
Driver
BP
State
logic Idle & Data
Detection
R_bias
SplitTermination,
Termination,
Split
HighOhmic
Ohmic
High
5 5
Topology A
MiddleTermination
Termination
Middle
(as displayed above)
(as displayed above)
Topology B
Topology A
C_out / 2
Topology B
Figure 3: Structure of FlexRay Topologies
Fig. 3. Structure
topologies.
Figureof3:FlexRay
Structure
of FlexRay Topologies
Gnd
slope correctly, capacitive effects of the transceiver device are
modelled
using output capacitors.
NMOS
NMOS
Figure
1: Schematic
Structure
of Output
Driver
of FlexRay
Transceiver
Model
Fig.
1. Internal
structure
of output
driver
of FlexRay
transceiver
model.
2
1.5
1.5
1
0.5
2m
0
6m
2m
-0.5
5
-0.5
-1.5
R3
C3
Split Termination,
High Ohmic
5
-1 Topology A
-1
R2
Split Termination,
Adapted
4
4
0
R1
6m
S1
0.5
BP
BM
C2
C1
2 Simmulation
6m
Simmulation
2 Measurement
m
S1
Measurement
2,5 m
3
3
2m
1
Amplitude [V]
For signal integrity
Gndinvestigations the most important part
of the bus transceiver
model is the output driver. The model is
Gnd
Figure
2: Schematic
Structureapproach
of Output
Modelin
Vcc Driver
based
on
a
physical
whichofisFlexRay
shownTransceiver
schematically
gnal
: Schematic
Structure
of
Output
Driver
of
FlexRay
Transceiver
Model
Bus
Driver
Figure 2. The three possible bus levels belonging to the internal
the
With
several
parameters
like
the
PMOS
transceiver
states
idle, active
lowswitching
and activevoltages
high are of
realized
with MOSFETs
R_bias
and
diodes
and
parameters
of
the
control
function
th
several
parameters of
liketwoswitching
voltages of
thework itas
by interconnection
MOSFET transistors.
They
put is possible
C_out / 2of the
to
match
details
of
signal
integrity
behavior
controlled
switches
based of
on the
the control
MOSFET
equations
ETs and
diodes and
parameters
function
it and
ose
model
with details
thebusbehavior
ofintegrity
the ground
realbehavior
transceiver
device.
connect
the
output
pin
with
or
supply
voltage,
sible
to
match
of
signal
of
the
l to Datasheet
TxEN
information
and of
measurement
data The
is used
for this.
depending
on
the
state
the
transceiver.
adaption
ofVout
the
State
with
the
behavior
of
the
real
transceiver
device.
able
switching
behavior
and
of
the
bus
levels
is
done
with
a
logic
ver information
An advantage
of this behavioral
modeling
heet
datathe
is series
used
for
this.approach
TxD and measurement
(BP,
differentiable
control
function
and
connection
of
two
R_bias
der compared to behavioral modeling approaches simply using
BM)
diodes. When
idle, behavioral
both transistorsmodeling
are in high impedance
C_out / 2 mode
of this
approach
ionadvantage
measured
characteristic
curves
[2]
is
the
possibility
to
integrate
and
the transceiver
is readyapproaches
for signal reception.
An
additional
redfor
to example
behavioral
modeling
simply
using
temperature
and
supply
voltage
dependencies
of
ohmic voltage
divider is
used
to model
the correct
impedance
red the
characteristic
curves
[2]
is
the
possibility
to
integrate
transceiver
device
in
the
model
quite
easily.
By
using
basic
behavior in this case andNMOS
provide the bias voltage. To ensure
ample
temperature
and
voltage
dependencies
of
physical
equations
the
influences
ofconditions
several
quantities
can be
correct
behavior
in supply
different
load
and to model
the
5
5
(BP,
(BP,
BM)
C_outBM)
/2
CC33
Split
SplitTermination,
Termination,
Adapted
Adapted
6 m6 m
2m2m
uBus
R2
1
RR
33
4 4
4
4
C2
R2
6 m6 m
S1
BM
Vout Vout
uBus_lpf Lowpass
Filter
R_bias
3 3
2m2m
BM
RR
1
S1 S1 2,5 m
2,5 m
3
S1
C1
6m
2m2m
R_bias R_bias
/2
C_out
/ C_out
2
Driver
TxEN_del
TxEN
Delay
3
BP
BP
BM
CBM
2
C1
2
6m
2
2m2m
BP
Amplitude [V]
etic
cial
gate
ural
cht
TxE
N
2
Middle Termination
(as displayed above)
Topology B
Figure 3: Structure of FlexRay Topologies
0
0.2
0.4
0.6
0.8
1
Time [s]
1.2
1.4
x 10
1.5
-1.5
1.6
-6
Amplitude [V]
0 Figure
0.2 4: Simulation
0.4Simmulation
0.6and Measurement
0.8
1 Results
1.2 for1.4
1.6 A
Topology
integrated
directly.
nsceiver
device
in the model quite
Gnd easily. By using basic
Time [s]results for topology A. x 10-6
Fig. 4. Simulation and
measurement
Measurement
1
al equations the influences of several quantities can be
Topology
B alsoand
includes
5 busResults
nodesforconnected
Figure 2: Schematic
Structure
of Output
Driver of FlexRay
Transceiver Model
Figure
4: Simulation
Measurement
Topology Awith a
Behavior
of
SI
model
in
typical
FlexRay
networks
atedB.directly.
Fig. 2. Schematic structure of output driver of FlexRay transceiver
network containing different line lengths. Node 1 is sending
0.5
2.2 onto
Behavior
of SI model
typical
FlexRay
networks
The model.
models
for the parameters
bus systemlike
component
verified
With several
switchingwere
voltages
of the Topology
data
Figurein
shows
theconnected
signal
traces
Bthe
alsobus.
includes
5 5bus
nodes
withofa
with of
measurement
each
component
individually.
ehavior
SI model and
in results
typical
FlexRay
networks
MOSFETs
diodes for
and
parameters
of the control
function it simulation and measurement at node 3. Again very good
network
different
line
lengths.were
Node
1 iswith
sending
Thecontaining
models
for the
bus
system
component
verified
0 between
The signal
integrity
behavior
validated
at several
is possible
to match
detailswas
of signal
integrity
behaviorload
of the agreement
simulation
and measurement
data can be
e models
forWith
the
bus
system
component
were
verified
data
onto
the
bus.
Figure
5
shows
the
signal
traces
of
several
parameters
like
switching
voltages
of
the
measurement
results
for
each
component
individually.
The
model Good
with theagreement
behavior of
the realsimulation
transceiver and
device. seen.
conditions.
between
measurement
results
for
each
component
individually.
simulation
and
measurement
at
node
3.
Again
very
good
MOSFETs
and
diodes
and
parameters
of
the
control
funcsignal
integrity
behavior
was
validated
at
several
load
condiDatasheet
information
and
measurement
data
is
used
for
this.
measurement data could be achieved.
-0.5
ignal integrity
was
validated
several
load
agreement
between
simulation
measurement
data can be
tion it behavior
is possible to
match
details ofatsignal
integrity
behavior
tions. Good
agreement
betweenand
simulation
and measurement
An
advantage
ofbetween
this ofbehavioral
modeling
approach
2
theagreement
simulation
two
FlexRay
busand
system
ions. Below
Good
simulation
of the
model
with theresults
behavior
of
the
real transceiver
device.
seen.
data
could
be
achieved.
-1
Simulation
compared
toinbehavioral
approaches
simplyand
using
topologies
shown
Figure and
3 modeling
are
presented
as example
rement
data
could
be
achieved.
Datasheet
information
measurement
data
is usedtofor
this.
Below
the simulation
results of two FlexRay bus system
1.5
Measurement
measured
characteristic
curves
[2] is the possibility
integrate
Amplitude [V]
and A
measurement
dataforatthe
node
4.
The
agreement
between
quantities
can
be 5integrated
directly.
The
models
bus
system
component
were
verified
pology
isofaseveral
chain
connection
of
bus
nodes
connected
model behavior
and measurement
values
is component
very good. individually.
with
measurement
results
for
each
bus lines with a length of 2 meters each. Node 1 is
The signal integrity behavior was validated at several load
g. Figure conditions.
4 shows the
comparison
simulation
Good
agreementbetween
between
simulation and
measurement
data
at
node
4.
The
agreement
between
measurement data could be achieved.
behavior and measurement values is very good.
Below the simulation results of two FlexRay bus system
Adv. Radioshown
Sci., 9,in111–116,
topologies
Figure 32011
are presented as example and
compared with measurement data. It is shown that with the
help of simulation based investigation conclusions about real
world behavior of bus systems can be drawn.
topologies
-1.5 shown in Fig. 3 are presented as example and
2
0 with0.2
0.4
0.6 data.
0.8 It is
1 shown
1.2 that
1.4 with
1.6the
1
compared
measurement
Simulation
-6
Time [s]
help0.5
of simulation
based investigation conclusions aboutx 10
real
1.5
Measurement
Figure 4: Simulation
and Measurement
Results for Topology A
world behavior
of bus systems
can be drawn.
1 Topology
A is a chain connection of 5 bus nodes connected
0
Topology
B also includes 5 bus nodes connected with a
with
bus
lines
with a length
of line
2 m each.
1 1is is
sendnetwork
containing
different
lengths.Node
Node
sending
0.5
-0.5
ing.
Figure
4
shows
the
comparison
between
simulation
and of
data onto the bus. Figure 5 shows the signal traces
measurement
data at
node 4. The at
agreement
and
measurement
node 3. between
Again model
very good
-1
0simulation
behavior
and
measurement
values
is
very
good.
agreement between simulation and measurement data can be
-1.5
-0.5seen.
Amplitude [V]
compared An
with
measurement
data. It ismodeling
shown that
with comthe
advantage
of this behavioral
approach
for
exampleresults
temperature
and FlexRay
supply
voltage
dependencies
of
lowhelp
the of
simulation
of two
bus
system
simulation
based investigation
conclusions
about
real
pared
to behavioral
modeling
approaches
simplyBy
using
meathe
transceiver
device
in
the
model
quite
easily.
using
basic
behavior
of bus3systems
can(IBIS
be drawn.
giesworld
shown
in Figure
arecurves
presented
as example
and is the
Open
Forum,
2009)
sured
characteristic
physical
equations the
influences
of several
quantities
can be
red with
measurement
data.
It
is
shown
that
with
the supply
possibility
to
integrate
for example
and
integrated
Topology
A isdirectly.
a chain
connection
of 5 temperature
bus nodes connected
f simulation
based
investigation
conclusions
aboutin
real
voltage
dependencies
of the
transceiver
the model
with bus
lines
with
a length
of
2 meters device
each.
Node
1 is
behavior
of
bus
systems
can
be
drawn.
B.
Behavior
of using
SI model
in physical
typical FlexRay
networks
quite
easily.
By
equations
the
influences
sending.
Figure
4 shows
thebasic
comparison
between
simulation
-2
-1
1.5
-1.5
-2
0 2
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
-6
Simulationwww.adv-radio-sci.net/9/111/2011/
Time [s]
x 10
Measurement
Figure 5: Simulation and Measurement Results for Topology B
1
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
data onto the bus. Figure 5 shows the signal traces of In VHDL-AMS the transceiver behavior can be modeled as
simulation and measurement at node 3. Again very goodcombination of discrete elements and variable input
agreement between simulation and measurement data can beimpedances (V/I- and f/Z-tables) which can be found by
measuring the DC V/I characteristic and the impedance in
seen.
H. Günther et al.: Modeling automotive FlexRay transceivers for signal integrity and EMC simulations
113
0
failure point in frequency domain.
ystem
e and
h the
t real
2
1.5
Input Impedance
Simulation
Measurement
1 MΩ
BP
Amplitude [V]
1
1 pF
BM
0.5
Comparator
+
100 kΩ
rified
ually.
load
and
Low Pass
Filter
500 Ω
1 MΩ
Figu
The v
by resona
Digital
Unit
Digital
Behavior
1
Rx
10 pF
D. Inve
with E
To p
protectio
transceiv
AMS mo
2 kΩ
I [A]
2 kΩ
ected
e 1 is
0
10 pF
10 pF
lation
-0.5
ween
ESD
against
r
current increases
Below
45 V receiver
both transceivers
have
EMC Simulation
Model of FlexRay Transceivers
-1
Figure 6.critically.
Behavioral model
of FlexRay
input
CW-coup
Fig.
6.
Behavioral
model
of
FlexRay
receiver
input.
high impedances.
Because of the nonlinear behavior of the transceivers for
thermal p
-1.5
Figure 7 shows sample V/I-measurement results done with
bypassed
MC modeling, not only the determination of the stationary
8 TLP [7] of two typical FlexRay transceivers. At levels
HPPI
simulatio
TLP: FlexRay Type A Bus Minus <-> GND
pedance is important,
but also the dynamic behavior in case
-2
over
45
–
50
V
internal
ESD
circuits
may
switch
and
the
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
TLP: FlexRay Type B Bus Minus <-> GND
done wit
7
bus communication failure [4], [5]. Time
In other
investigations -6
[s]
x 10
e input impedance of IC’s were mostly determined by the
6
Figure 5: Simulation and Measurement Results for Topology B
flection measurements
of
the
input
pins
and
potential
ESD
Fig. 5. Simulation and measurement results for topology B.
5
otection elements were implemented as simple diode models
4
]. The nonlinear effects near or over critical values are not
nsidered in Topology
these examinations.
In
[5]
investigations
on
3
B also includes 5 bus nodes connected with a
odeling of network
CAN and
FlexRay
transceivers
wereNode
made
containing
different
line lengths.
1 isand
sending
2
ry simpledataequivalent
onto the bus. impedance
Figure 5 showsmodels
the signal for
tracesEMC
of simula1
mulations were
presented.
However
behavior
case
of
tion and
measurement
at nodethe
3. Again
very in
good
agreement
nsient disturbances
or
the
partial
destruction
of
bits
by
0
between simulation and measurement data can be seen.
mplitude modulated signals in combination with ESD
-1
otection circuits
and the
transceiver
internal
signaltransceivers
processing
0
10
20
30
40
50
60
70
80
2.3 EMC
simulation
model
of FlexRay
V [V]
not considered. The receiver unit of a differential bus
nsceiver can
be modeled as ideal high impedance
Because of the nonlinear behavior of the transceivers for
Fig. 7.
TLP7. measurement,
V/I characteristic
of tested
FlexRay
Figure
TLP measurement,
V/I characteristic
of tested
mparator with
low pass filter. High frequencies or fast
EMC modeling, not only the determination of the stationtransceivers.
FlexRay transceivers
nsient pulses
may not affect
the correct
detection
of the
ary impedance
is important,
but also
the dynamic
behavgnal and pulse
width.
In
Table
I
the
equivalent
RC-circuits
ofFrei,
ior in case of bus communication failure (Hilger and
In Figure 8 the frequency dependent critical failure voltages
vestigated bus
transceivers
shown. the input impedance of IC’s
of the signal
and the digital
is modeled Because
as ideal of
2008a,b).
In otherare
investigations
of parts
the FlexRay
transceivers
areunitpresented.
A/D-D/A
converter.
were
mostly determined
reflection Bmeasurements
of constructive variations and internal signal processing the
ABLE I.
EQUIVALENT
IMPEDANCES by
OF Ithe
NVESTIGATED
US DRIVERS
In VHDL-AMS
the transceiver
behavior can be modthe input pins and potential ESD protection elements were transceivers
have different
immunity levels.
Transceiver
CAN as
Type
A FlexRay
Type A (Boyer
FlexRayet
Type
implemented
simple
diode models
al., B2007).
eled as combination of discrete elements and variable input60impedances (V/I- and f/Z-tables) which
canVoltage
be found
by
Critical
Type A
measuring the DC V/I characteristic andCritical
the impedance
Voltage Type Bin
50
failure
point in frequency domain.
Figure 7 shows sample V/I-measurement results done with
HPPI
40 TLP (HPPI Transmission Line Pulser, 2010) of two
typical FlexRay transceivers. At levels over 45–50 V internal
ESD
30 circuits may switch and the current increases critically.
Below 45 V both transceivers have high impedances.
In Fig. 8 the frequency dependent critical failure volt20
ages of the FlexRay transceivers are presented. Because
of 10
constructive variations and internal signal processing the
transceivers have different immunity levels.
The voltage change between 90 and 100 MHz are caused
0
by resonances
in the measurement
1
10 setup.
100
The nonlinear effects near or over critical values are not con10 pF || 2 kΩ
42 pF || 20 kΩ
sidered in these examinations. In Hilger and Frei (2008b) investigations on modeling of CAN and FlexRay transceivers
madea and
very simple
equivalent
impedance
Figure 6 were
shows
simple
behavioral
model
of themodels
bus for
simulations
were presented.
However
the behavior
ceiver withEMC
equivalent
impedance
bus load,
comparator
and in
case of transient disturbances or the partial destruction of bits
w pass filter.
by amplitude modulated signals in combination with ESD
The comparator
detects
the internal
differential
protection
circuitsand
and amplifies
the transceiver
signal bus
processltage. The ing
connected
low
pass
will
filter
all
high
frequency
is not considered. The receiver unit of a differential bus
rts of the signal
and the
unit isasmodeled
as impedance
ideal A/D-comtransceiver
candigital
be modeled
ideal high
A converter.
parator with low pass filter. High frequencies or fast transient
pulses may not affect the correct detection of the signal and
In VHDL-AMS
the transceiver behavior can be modeled as
pulse width. In Table 1 the equivalent RC-circuits of investimbination of discrete elements and variable input
gated bus transceivers are shown.
pedances (V/I- and f/Z-tables) which can be found by
f [MHz]
6 shows
a simple behavioral
of the bus
easuring the Figure
DC V/I
characteristic
and the model
impedance
in receiver
with equivalent
lure point in
frequency
domain.impedance bus load, comparator and
Figure 8. Critical failure voltage of tested FlexRay transceivers
low pass filter.
The comparator detects and amplifies the differential bus
The voltage change between 90 and 100 MHz are caused
Low Pass
Digital
Comparator
Input Impedance
voltage. The connected low passFilter
will filter allUnit
high frequency by resonances in the measurement setup.
Vcrit. [V]
quivalent Impedance 12 pF || 450 Ω
1 MΩ
M
+
100 kΩ
P
www.adv-radio-sci.net/9/111/2011/
500 Ω
1 pF
1 MΩ
10 pF
Digital
Behavior
Rx
D. Investigations of FlexRay
Combination
Adv.Transceivers
Radio Sci., 9,in
111–116,
2011
with ESD Protection Circuits
To perform EMC simulations in combination with ESD
protection circuits for signal integrity investigations the
-1
0
10
20
30
40
V [V]
50
60
70
80
A comparison between simulation and measurement is
given
in Figure 10.between
The voltages
are limited
by the protection
A comparison
simulation
and measurement
is
Transceiver
CAN Type A element.
FlexRayAtType
A FlexRay
Type B of about 8 V, the transceiver
disturbance
amplitude
given in Figure 10. The voltages are limited by the protection
In Figure 8 the frequencyEquivalent
dependent
critical failure
can not
detect
voltage
anymore.
The
disturbed
Impedance
12 pF voltages
|| 450 
10 pFAt
|| disturbance
2 kthe differential
42 pF
|| 20 k
element.
amplitude
of about
8 V, the
transceiver
of the FlexRay transceivers are presented. Because can
of
differential
bus
signal
with
the
resulting
bit
errors
can
be seen
not detect the differential voltage anymore. The disturbed
constructive variations and internal signal processing the
below. Thebus
correlation
between
simulation
and measurement
differential
signal with
the resulting
bit errors
can be seen
transceivers have different immunity levels.
results The
is very
good. between simulation and measurement
below.
correlation
60
results 10
is very good.
Figure 7. TLP measurement, V/I characteristic of tested
FlexRay transceivers
Critical Voltage Type A
Critical Voltage Type B
Vcrit. [V]
Measurement BP
Measurement BM
Measurement
Simulation BPBP
Measurement
BM
Simulation BM
Simulation BP
Simulation BM
105
V [V]
V [V]
40
50
0 -5
Voltage
cut off
-5-10 Voltage
-1
cut
off
-10
30
-1
4
20
Voltage
cut off
Voltage
0
cut off
-0,5
t [µs]
0
t [µs]
-0,5
TxD
TxD
TxE
N
TxE
NRxD
1
0,5
1
Measurement VDiff
Simulation V
Measurement Diff
VDiff
BP
20
To
verify the low pass filter characteristics Simulation
and theVDiffdigital
behavioral
model in combination with ESD protection circuits
0 -2
1
10
100
measurements
at high and low frequencies
were done. In
Bit Error
Bit Error
According to the DPI method
[9] the noise voltage will be
f [MHz]
-2-4 11 a comparison between the simulation with the
Figure
coupled to both bus lines through the termination resistors and
-1Bit Error
0Bit Error
0,5
1
behavioral
model -0,5
and a measured
signal of
the FlexRay
-4
t [µs]
a Fig.
capacitor.
Figure
9 the voltage
simulation
andFlexRay
measurement
setup
8. Critical
failure failure
voltage
of tested
FlexRay
transceivers.
Figure
8.In Critical
of tested
transceivers
-1
0
0,5
1
transceiver
can be-0,5
seen. The transceiver
is combined
with the
is shown.
t [µs]
Protek
TVSSimulated
array. Interference
frequency
is 50
MHz interference
and the
Figure 10.
and measured
differential bus
voltage,
Fig. frequency
10.amplitude
Simulated
and
measured
differential
buspresented
voltage,
interferThe voltage change between 90 and 100 MHz are caused injected
is
20measured
V.FlexRay
The differential
correlation
curves
1 MHz
with
Type A andofProtek
TVS Array
BP
BP
50 Ω
Figure
10. Simulated
andwith
bus voltage,
interference
BP
ence
frequency
1
MHz
FlexRay
Type
A
and
Protek
TVS
Array.
ESD
by resonances
in the measurement setup.
is good.
Transceiver
frequency 1 MHz with FlexRay Type A and Protek TVS Array
The TVS array has a breakdown voltage of 6 V@1 mA and a
parasitic
impedance of 1.4 pF || 100 kΩ.
0
model
protection
model
50 Ω
FlexRay-Bus
6
4.7 nF
BM
50 Ω
Source
V [V]
Vcc
TxD
Vcc
PMOS
R_bias
C_out / 2
BP
Driver
BP
TxD_del
TxD
Delay
TxEN
TxD
V [V]
TxE
N
TxEN_del
TxEN
Delay
RxD
Vout
State
logic
R_bias
BM
Driver
BM
uBus_lpf Lowpas
s Filter
Idle &
Data
Detection
C_out / 2
(BP,
BM)
NMOS
uBus
Gnd
Gnd
Diff
Diff
V [V]
1 MΩ
1 pF
500
1 MΩ
2 kΩ
10 pF
5
4
Simulation Rx output
Simulation UDiff BP/BM
3
2
10 pF
Figure 12. Common parts of SI and EMC transceiver model
Measurement Rx output
Measurement UDiff BP/BM
Adv. Radio Sci., 9, 111–116, 2011
10 pF
in
inLot
pre
Low
in
pres
ininf
info
Bus Driver
Vcc_reg
Voltage
Regulato
r
6
BM
BM
65
III.
V [V]
BM
BP
Measurement Rx output
Measurement UDiff BP/BM
D. Investigations of FlexRay Transceivers in Combination
~
A COMBINED FLEXRAY TRANSCEIVER
MODEL
FOR
Measurement
Rx output
Termination
Simulation Rx output
Measurement UDiff BP/BM
with ESD Protection Circuits
SI AND EMC SIMULATIONS
54
Simulation UDiff BP/BM
Simulation Rx output
presented SI model of the FlexRay
transceiver mainly
To9.perform
EMC
simulations
with ESD The
Test setup
incoupling in
withcombination
DPI method
Simulation UDiff BP/BM
43
Fig.
TestFigure
setup9.
incoupling
with
DPI method.
protection circuits for signal integrity investigations the focuses on the output behavior of the bus driver, while the
A comparison
measurement
is
32
presented
EMC model reflects the input behavior of the circuit.
transceiver
models between
can be simulation
modularly and
extended
with VHDLgiven
in
Figure
10.
The
voltages
are
limited
by
the
protection
Integration of the two models to a combined SI and EMC
AMS
models
of
protection
elements.
21
2.4 Investigations
FlexRayoftransceivers
combinaelement.
At disturbanceofamplitude
about 8 V, theintransceiver
transceiver
simulation model is possible. Figure 12 gives an
with
protection
canESD
nottion
detect
theESD
differential
voltage
anymore.for
Thethe
disturbed
protection
elements
arecircuits
intended
protection overview
of the common parts of the two models.
10
differential
bus occurring
signal withpulses.
the resulting
bit errors operation
can be seenwith
against
rarely
A permanent
0-1
To perform
EMC the
simulations
in voltage
combination
with
ESDThe
below.
The correlation
between
simulation
and
measurement
CW-coupling
above
breakdown
is not
possible.
results
is
very
good.
protection
circuits
for
signal
integrity
investigations
the
thermal power, generated by a coupled CW-current, can not be
-1-2
transceiver
models
be modularly
extended with
VHDL10
bypassed
and
will can
leads
to destruction.
The
immunity
Measurement BP
-2-3
AMS5 models
of protection
BM
simulations
with
sinusoidalelements.
disturbances Measurement
were exemplarily
0
100
200
300
400
500
600
Simulation BP
t [ns]
ESD
protection
elements
are
intended
for
the
protection
done with
a
TVS
diode
array
from
Protek
type
GBLCS05C.
-3
Simulation
BM
0
0
100
200
300
400
500
600
against rarely occurring pulses. A permanent operation with
t [ns]
-5 Voltage
Figure 11. Comparison between simulated and measured signal of
Voltage
CW-coupling
above the breakdown
voltage is not possible.
a FlexRay transceiver
cut off
off
Figure
Comparison
between
simulatedand
andmeasured
measured signal
signal of a
The -10
thermal
power, generated bycut
a coupled
CW-current, can
Fig. 11. 11.
Comparison
between
simulated
-1
-0,5
0
0,5
1
a
FlexRay
transceiver
FlexRay
transceiver.
not be bypassed and will leads
to
destruction.
The
immunity
t [µs]
Structure of SI transceiver model
Structure of output driver
simulations
with sinusoidal disturbances were exemplarily
4
Measurement V
done2with a TVS diode array from Protek type
GBLCS05C.
Digital
Comparator
Low Pass
Input Impedance
Simulation V
Unit
Filter
+
tion element. At
disturbance
amplitude of
about 8 V, the
BP
The TVS array has a breakdown voltage of 6 V@1 mA and a
Transmitter
Rx
0
Digital
Ω
transceiver can not detect
the
differential
voltage
anymore.
parasitic impedance of 1.4 pF || 100 k.
Behavior
Output Driver
BM
-2
The disturbed differential
bus signal with the resulting bit erAccording
to the DPI method (IEC 62132-4:2006, 2006)
Lowpass Filter
Bitvoltage
Error will be coupledBit
rors can be seen below. The correlation between simulation
the noise
toError
both bus lines through the
-4
Digital
Behavior
-1
-0,5
0
0,5
1
and measurement results is very good.
termination resistors and a capacitor.
In Fig. 9 the simulation
t [µs]
Output Impedance
and measurement setup is shown.
To verify the low pass filter characteristics and the digital
Figure 10. Simulated and measured differential bus voltage, interference
Structuremodel
of EMCin
transceiver
model with ESD protection cirbehavioral
combination
A frequency
comparison
between
simulation
and
measurement
is
1 MHz with FlexRay Type A and Protek TVS Array
given in Fig. 10. The voltages are limited by the proteccuits measurements at high and low frequencies were done.
BM
foc
pre
focu
Int
pres
tra
Inte
ov
tran
ove
RxD
0,5
42
10
with
evels
the
is
inje
is g
Figure 9. Test setup incoupling with DPI method
Table 1. Equivalent impedances of investigated bus drivers.
bus
and
Rx
4.7 nF50 Ω
Figure 9. Test setup incoupling with DPI method
50
ed as
nput
d by
e in
50 Ω
Termination 4.7 nF
kΩ
bus
ency
A/D-
50 Ω
FlexRay-Bus
ESD
model
protection
50 Ω
BM
BM FlexRay-Bus
model
100 kΩ
pe B
114
BPprotection
BP
~ Source
BM
50 Ω
BM
BM
~ Source
H. Günther et al.: Modeling automotive FlexRay transceivers for signalTermination
integrity and EMC simulations
0
2 kΩ
VERS
Transceiver
BP
model
Transceiver
model BM
1
V [V]
V [V]
EMC
se of
s by
ESD
ssing
bus
ance
fast
f the
ts of
The transmitting part with
the output drivers is present only
www.adv-radio-sci.net/9/111/2011/
in the SI model, thus it will be used for the combined model.
Lowpass filter, digital behavior, and output impedances are
present in both SI and EMC models, but show big similarities
Ve
to
Ver
towim
sim
with
ne
sim
of
netw
ofAct
Acc
d measurement is
presented EMC model reflects the input behavior of the circuit.
d by the protection
Integration of the two models to a combined SI and EMC
8 V, the transceiver
transceiver simulation model is possible. Figure 12 gives an
Günther et al.: Modeling automotive FlexRay transceivers for signal integrity and EMC simulations
more. TheH.disturbed
overview of the common parts of the two models.
errors can be seen
n and measurement
Vcc
Vcc
TxD
PMOS
R_bias
C_out / 2
BP
Driver
BP
TxD_del
TxD
Delay
Bus Driver
Vcc_reg
Voltage
Regulato
r
Measurement BP
Measurement BM
Simulation BP
Simulation BM
TxEN
TxEN_del
TxEN
Delay
RxD
R_bias
BM
Driver
BM
uBus_lpf Lowpas
s Filter
Idle &
Data
Detection
Vout
State
logic
TxD
TxE
N
115
C_out / 2
(BP,
BM)
NMOS
uBus
Gnd
Gnd
0,5
1
Structure of SI transceiver model
Structure of output driver
Measurement VDiff
Input Impedance
Simulation VDiff
Comparator
1 MΩ
1 pF
+
100 kΩ
BP
Digital
Unit
Ω
Digital
Behavior
500
1 MΩ
BM
Low Pass
Filter
Transmitter
Rx
Output Driver
-
0,5
1
10 pF
2 kΩ
2 kΩ
10 pF
Lowpass Filter
10 pF
Digital Behavior
Output Impedance
voltage, interference
otek TVS Array
with two 1.3 kΩ resistors, nodes 2 and 3 with two 47 Ω
Structure of EMC transceiver model
resistors and each with 4.7 nF to GND. Common mode chokes
or other protection elements are not used in this setup. The BCI
clamp
is positioned
onmodel
the cable of node 2 in a distance of
Figure 12. Common parts of SI and
EMC
transceiver
0.2 m.
Fig. 12. Common parts of SI and EMC transceiver model.
ement Rx output
ement UDiff BP/BM
In Fig. 11 a comparisonThe
between
the simulation
thethe output drivers
transmitting
partwith
with
is present only
1m
Node 3
model and
a
measured
signal
of
the
FlexRay
Ω
in the SI model, thus it will be used94 for
the combined
model.
Passive Star
transceiver can be seen. The transceiver is combined with
Lowpass
filter,
digital
behavior,
and output impedances are
the Protek TVS array.
Interference
frequency
is 50 MHz
and
Node
4 0.65
1.2 m
m big similarities
present
in
both
SI
and
EMC
models,
but
show
the injected amplitude is 20 V. The correlation of presented
2.6 kΩ
m
curves is good.
in general parts. The EMC model contains additional
RF Power
ion Rx output
behavioral
ion UDiff BP/BM
BCI Clamp
0.2 m Node 2
94 Ω
information about differential impedances and operation limits.
3
2m
A combined FlexRay transceiver model for SI and
EMC simulations
Node 1
2.6 kΩ
In o
operati
transce
model
while
compar
shows,
SI and
taken f
informa
Digital
combin
results
injectio
IV. SIMULATION OF BCI TEST WITH
Figure
13. BCI
setup
with passive
starfour
and four
nodes
BCI test
setuptest
with
passive
star and
nodes.
NODE
FLEXRFig.
AY13.
NETWORK
The presented SI model of the FlexRayFOUR
transceiver
mainly
focuses on the output behavior of the bus driver, while the
shows a comparison between the simulated and
With a VHDL-AMS model of aFigure
BCI14clamp
from Fehler!
presented EMC model reflects the input behavior of the cir- measured voltages at different FlexRay nodes. The
Verweisquelle
konnte
nicht
gefunden
werden.
it test
isinpossible
were
done
the four
frequency
domain with a
4 Simulation
of BCI
with
node FlexRay
cuit. Integration of the two models to a combined SI and measurements
500
600
analyzer
in the time domain with a signal
network
to makemodel
virtual
CAN orFigure
FlexRay
network
tests. and
In combination
EMC transceiver simulation
is possible.
12 network
and oscilloscope. Here higher input power and active
gives an overview ofwith
the common
parts
of the two
models.
a cable
model
[10]
and the generator
transceiver
models an overall
voltage
probes
were used. The BCI clamp was supplied with
The transmitting simulation
part with the model
output drivers
is
present
With
ainvestigate
VHDL-AMS model
of a BCI clamp from Hilger et
can
be
created.
To
an over
extended
constant power of 10 dBm
all frequencies. The parasitic
measured signal
only of
in the SI model, thus it will be used for the comal.
(2010)
it
is
possible
to
make
virtual
CANelements,
or FlexRay
effects of connectors,
the PCB
and
discrete
like
network
4
FlexRay
nodes
are
interconnected
with
cable
models
bined model. Lowpass filter, digital behavior, and output resistors
networkand
tests.
In
combination
with
a
cable
model
(Zhang
capacitors, were considered in the model.
The
of twisted
In Figure
BCI
setup
is shown.
impedances are present
in both pair
SI andcables.
EMC models,
but 13
etthe
al., shows
2008) test
and the
transceiver
models
simulamodel
very
good
correlation
up to an
200overall
MHz between
show big similaritiesAccording
in general parts.
The EMC
model conto [8]
all nodes
are split
1Toand
4
tionterminated.
model
be Nodes
created.
investigate
an extended netsimulated
andcan
measured
results.
tains additional information about differential impedances
work 4 FlexRay nodes are interconnected with cable mod2.5 twisted pair cables. In Fig. 13 the BCI test setup is
and operation limits.
els of
V1, measurement
V2, measurement
shown. According to FlexRay Protocol Specification
(2005)
V3, measurement
all nodes
are
split
terminated.
Nodes
1
and
4
with
two
1.3
k
2
V4, measurement
V1, simulation
resistors, nodes 2 and 3 with two 47  resistors
and each
1.5
Adv. Radio Sci., 9, 111–116, 2011
V [V]
www.adv-radio-sci.net/9/111/2011/
V2, simulation
V3, simulation
V4, simulation
1
[1]
H.
of A
[2] IBI
ava
[3] U.
Tra
Ext
[4] U.
Sim
[5] U.
sin
Sch
[6] A.
Agr
6th
Inte
[7] HP
[8] Fle
[9] IEC
ele
inje
[10] H.
Tra
IEE
[4]
U. Hilger, S. Frei: Modellierung von LIN-Transceivern für EMV-
Simulationen im Kraftfahrzeug, EMV 2008, VDE Verlag
effects of connectors, the PCB and discrete elements, like
[5] U. Hilger, S. Frei: Störfestigkeit von Bustransceivern gegen
resistors and capacitors, were considered in the model. The
sinusförmiger Stögrößen in Verbindung mit nichtlinearen ESDmodel shows very good correlation up to 200 MHz between
Schutzelementen,
EMV 2008,
VDE and
Verlag
116
H.
Günther
et
al.:
Modeling
automotive
FlexRay
transceivers
for signal
integrity
EMC simulations
simulated and measured results.
[6]
2.5
V1,
V2,
V3,
V4,
V1,
V2,
V3,
V4,
2
V [V]
1.5
measurement
measurement
measurement
measurement
simulation
simulation
simulation
simulation
1
0.5
0
0
50
100
f [MHz]
150
200
Figure 14. Comparison between simulated and measured amplitudes at the
four FlexRay
nodes
Fig. 14. Comparison between
simulated
and measured amplitudes
at the four FlexRay nodes.
with 4.7 nF to GND. Common mode chokes or other protection elements are not used in this setup. The BCI clamp is
positioned on the cable of node 2 in a distance of 0.2 m.
Figure 14 shows a comparison between the simulated and
measured voltages at different FlexRay nodes. The measurements were done in the frequency domain with a network
analyzer and in the time domain with a signal generator and
oscilloscope. Here higher input power and active voltage
probes were used. The BCI clamp was supplied with constant power of 10 dBm over all frequencies. The parasitic
effects of connectors, the PCB and discrete elements, like resistors and capacitors, were considered in the model. The
model shows very good correlation up to 200 MHz between
simulated and measured results.
5
A. Boyer, S. Bendhia, E. Sicard.: Modeling of a Direct Power Injection
Agression on a 16 Bit Microcontroler Input Buffer, EMC Compo 2007,
References
6th International Workshop on Electromagnetic Compatibility of
Integrated Circuits, 2007
Boyer,
Bendhia,
S., and Sicard,
E.: Modeling
of a Direct
Power
[7] A.,
HPPI
Transmission
Line Pulser,
Type TLP3010,
http://www.hppi.de
Injection Agression on a 16 Bit Microcontroler Input Buffer,
[8] FlexRay Protocol Specification V2.1 Rev. A, http://www.flexray.com
EMC Compo 2007, 6th International Workshop on Electromag[9] IEC 62132-4:2006: Integrated circuits - Measurement of
netic Compatibility
of Integrated Circuits, 2007.
electromagnetic immunity 150 kHz to 1 GHz - Part 4: Direct RF power
FlexRay injection
Protocol method
Specification: V2.1 Rev. A, http://www.flexray.
com,
2005.
[10] H. Zhang, K. Siebert, S. Frei, T. Wenzel, W. Mickisch: Multiconductor
Günther, Transmission
H., Frei, S., and
T.: with
Simulation
Methods
SigLineWenzel,
Modeling
VHDL-AMS
for for
EMC
Applications,
nal Integrity
of Automotive
Bus Systems,
2010.
IEEE-EMC
2008 Symposium,
DetroitAPEMC,
2008
Hilger, U. and Frei, S.: Modellierung von LIN-Transceivern für
EMV-Simulationen im Kraftfahrzeug, EMV 2008, VDE Verlag,
2008a.
Hilger, U. and Frei, S.: Störfestigkeit von Bustransceivern gegen
sinusförmiger Stögrößen in Verbindung mit nichtlinearen ESDSchutzelementen, EMV 2008, VDE Verlag, 2008b.
Hilger, U., Miropolsky, S., and Frei, S.: Modeling of Automotive Bus Transceivers and ESD-Protection Circuits for Immunity Simulations of Extended Networks, EMC Europe, Wroclaw,
2010.
HPPI Transmission Line Pulser: Type TLP3010, http://www.hppi.
de, 2010.
IEC 62132-4:2006: Integrated circuits – Measurement of electromagnetic immunity 150 kHz to 1 GHz – Part 4: Direct RF power
injection method, 2006.
IBIS Open Forum: I/O Buffer Information Specification, Online,
available: http://www.eigroup.org/ibis, 2009.
Zhang, H., Siebert, K., Frei, S., Wenzel, T., and Mickisch, W.: Multiconductor Transmission Line Modeling with VHDL-AMS for
EMC Applications, IEEE-EMC 2008 Symposium, Detroit, 2008.
Conclusion
In order to investigate possible disturbances in bus system operation with simulation, behavioral models of bus
transceivers for SI and EMC investigations were developed. SI model focus mainly on the output behavior of the
transceivers, while EMC models reflect the input behavior. A
detailed comparison of two developed models for these applications shows, that integration into a combined transceiver
model for SI and EMC simulations is possible. Transmitter parts are taken from the SI model, since the EMC model
gives detailed information about output impedances and operation limits. Digital receiving parts are present in both
models. The combined model shows good matching with
measurement results in an application example with disturbance signal injection through a BCI clamp.
Adv. Radio Sci., 9, 111–116, 2011
www.adv-radio-sci.net/9/111/2011/