EMC Compo 2011
Dubrovnik
PhD Seminar
Name Niko Bako Institute University of Zagreb E-mail [email protected]
PhD Title High frequency cable modeling
Project “Golden gates”
Partner ON Semiconductor
Motivation & Objectives
• Motivation: • Automotive industry:
– The FlexRay comunication protocol » Future replacement for CAN » Developed from the year 2000 to the year 2010 » Baud rate: 10 Mbit/s
• Sensitivity to EMI
• Objectives: • Cable models valid up to 3 GHz within 3 dB mismatch
– Single-ended S parameters and mixed-mode S parameters – Valid for tools such as: Spectre, Hspice or Agilent ADS
• The models should be simple and stable: – Simple: static RCLG matrices if possible – Stable: static RLCG matrices are frequency independent - stability
• So far: – Only twisted pairs – The models are not based on geometry
06.11.2011 EMC Compo 2011 – PhD Seminar 2
Measurements & Modeling
• Measurements: – Frequency domain: single-
ended S parameters
– Cables 5 cm above ground plane
– Range: 300 kHz – 3 GHz
– Cables: • Length 1m
• 1 or 2 twisted pair
– Extracted single-ended S parameters • Test fixture must be de-
embedded – the fixtures must be modeled
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DUT: Cable 100 cm
Fixture Fixture
Fixture
x
y
-z
Test fixture
• Modeled in Agilent Momentum
• Comparison: measurement vs. model:
06.11.2011 EMC Compo 2011 – PhD Seminar 4
1E7 1E8 1E91E6 3E9
-70
-60
-50
-40
-30
-20
-10
-80
0
freq, Hz
Am
plit
ud
e, d
B
Reflection (S11)
Meas.
Model
1E7 1E8 1E91E6 3E9
-100
0
100
-200
200
freq, Hz
Phase, deg
Reflection (S11)
Model
Meas.
1E7 1E8 1E91E6 3E9
-1.5
-1.0
-0.5
-2.0
0.0
freq, Hz
Am
plit
ude, dB
Transmission (S12)
Meas.
Model
1E7 1E8 1E91E6 3E9
-100
0
100
-200
200
freq, Hz
Ph
ase
, d
eg
Transmission (S12)
Model
Meas.
1E7 1E8 1E91E6 3E9
-120
-100
-80
-60
-140
-40
freq, Hz
Am
plit
ude, dB
Coupling - far (S18)
Meas.
Model
1E7 1E8 1E91E6 3E9
-100
0
100
-200
200
freq, Hz
Ph
ase
, d
eg
Coupling - far (S18)
Model
Meas.
1E7 1E8 1E91E6 3E9
-100
-80
-60
-120
-40
freq, Hz
Am
plit
ude, dB
Coupling - near (S17)
Meas.
Model
1E7 1E8 1E91E6 3E9
-100
0
100
-200
200
freq, Hz
Phase, deg
Coupling - near (S17)
Model
Meas.
P1 P2
P7 P8
Measurements & Modeling
• Modeling - Challenges: – Stability of the model: in time domain
– Simplicity: • Frequency dependent RLCG matrices are not option
• Transmission lines are promising
– 4 port network (1 twisted pair): • Described with transmission line in range: 300 kHz – 3 GHz
• 2 conductors: – matrices are defined as lower triangular -> 3 (or 2) independent
variables
• E.g. L matrix
L11, L22 – self inductance
L12 =L21 – mutual inductance
– Mixed-mode parameters (MM): calculated from single-ended parameters (SE) -> model must be very accurate
06.11.2011 EMC Compo 2011 – PhD Seminar 5
11 12
21 22
L LL
L L
Measurements & Modeling • Model:
– The model includes:
• Connection to fixure: l≈0.3 cm
• Cable body: l≈100 cm
– Agilent ADS
– Transmission line model: W element • Telegraph equations, frequency dependent lossy transmission line
• Static RLGC matrices: the frequency dependence is analytically predefined. Frequency dependent resistance is modeled as:
Ro – DC resistance, Rs - freq. dependent parameter
– Assumption: electrical properties of both wires are the same
– The models are based on measured single-ended S parameters
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R R o R s(1 j) f
Body
Ref. plane
Results - SE parameters: measurements vs. model
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• Example - UTP FlexRay cable :
DUT: Cable 100 cm
Fixture Fixture
P2 P1
P3 P4
Results - SE parameters: measurements vs. model
06.11.2011 EMC Compo 2011 – PhD Seminar 8
• Coupling
• Near (P1-P3) Far (P1-P4)
Results - MM parameters: measurements vs. model
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• Differential – differential: reflection and transmission
Results - MM parameters: measurements vs. model
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• Common – common: reflection and transmission
Perspectives
• Industrial application:
– Project is supported by ON semiconductor
– The FlexRay communication protocol is future replacement for CAN protocol
• Future modeling:
– The models must be within 3 dB mismatch up to 3 GHz
– Improvement in mixed-mode parameters
06.11.2011 EMC Compo 2011 – PhD Seminar 11
Appendix • SE - reflection: lin
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Appendix • SE - transmission: lin
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Appendix • MM differential – differential reflection
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Appendix • MM common – common transmission
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