There are numerous design challenges associated with implementing Automotive Ethernet. This session will discuss what to test in order to improve the chances of a successful design

1. Automotive Ethernet Webinar
Physical Layer Compliance Testing
Bob Mart
Product Line Manager
robert.mart@teledyne.com

2. Upcoming Events: teledynelecroy.com/events
Live Seminar: Automotive Ethernet Day
Basics Of Automotive Ethernet and Physical Compliance
Santa Clara, CA
Live Seminar: Automotive Ethernet Day
Basics Of Automotive Ethernet and Physical Compliance
Farmington Hills, MI

3. Agenda
 What is Compliance Testing for Automotive Ethernet?
 Overview of Required Test Modes
 Description of Each Test
 Review of Required Test Equipment
 Hands on Testing
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4. Defining Automotive Ethernet
 Can refer to any Ethernet-based
network for in-vehicle electrical
systems
 Enables faster data
communication to meet rising
demand
 Specifically tailored to meet the
needs of automotive industry
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BroadR-Reach
Automotive Ethernet
100Base-T1
1000Base-T1
OABR
(OPEN Alliance
BroadR-Reach)
RTPGE
(Reduced Twisted
Pair Gigabit
Ethernet)

5. What is 100Base-T1?
 IEEE 802.3bw Physical Layer Specifications and Management Parameters for 100
Mb/s Operation over a Single Balanced Twisted Pair Cable (100Base-T1)
 IEEE specification for 100 Mb/s Automotive Ethernet
 Interoperable with OPEN Alliance BroadR-Reach
 Same RAND terms apply
 Nearly the same thing as BroadR-Reach
 Often times names are used interchangeably
 Few exceptions
 Electrical PMA has a Transmit Peak Differential Output
 Changes in the protocol timing for wake up commands
 Why create a new spec?
 Driven by other applications: industrial automation and avionics
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6. Physical Layer Compliance Testing
Overview of Compliance Testing

7. Categories of Automotive Ethernet Testing
 Electrical Signaling: Physical Media Attachment (PMA)
 Determine if product conforms to electrical transmitter and receiver
specifications
 Physical Coding Sublayer (PCS) & PHY Control
 Evaluates functionality of the protocol
 PCS transmit/receive
 State diagrams
 Encoding/decoding
 Scrambling/descrambling
 There are recommendations for other elements
 Common Mode Choke (CMC), EMC, Communication Channel, ECU, switches
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8. We will focus on Electrical Signaling
 Electrical Signaling: Physical Media Attachment (PMA)
 Determine if product conforms to electrical transmitter and receiver
specifications
 Physical Coding Sublayer (PCS) & PHY Control
 Evaluates functionality of the protocol
 PCS transmit/receive
 State diagrams
 Encoding/decoding
 Scrambling/descrambling
 There are recommendations for other elements
 Common Mode Choke (CMC), EMC, Communication Channel, ECU, switches
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9. What is Compliance Testing in the Context of Automotive Ethernet?
 The 100Base-T1 spec includes requirements for PMA, PCS, and PHY
Control
 IEEE does not write test specifications
 UNH has traditionally written test documents which describe how tests can
be performed
 It is up to the OEM, Tier 1, PHY Vendor, etc. to work with a test
equipment manufacturer or test house to perform testing
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10. Automotive Ethernet Test Suites
 OPEN Alliance licensed
UNL-IOL to create test suites for
each group of testing
 UNH-IOL maintains Test Suites
which contain a description of
how they perform testing
 These act as pseudo test specs
 PMA
 PCS
 PHY Control
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11. PMA Tests have two groups
 Group 1: Electrical Measurements
 Group 2: PMA Receive Tests
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12. PMA Electrical Measurements
 We will focus on the electrical
transmitter tests performed with
an oscilloscope
 There are also MDI tests which
are performed using a VNA
 MDI Return Loss
 MDI Mode Conversion Loss
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13. A Quick Note About PMA Receive Tests
 Group 2 is analogous to a
protocol level test
 PCS testing is typically done by
silicon vendors
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14. Why is PHY Compliance Important?
 OEMs have a lengthy development cycle for an ECU
 Need assurance that PHY chip meets requirements prior to implementation
 Once the PHY chip has been incorporated into the ECU it should also
be tested – testing is not just for PHY vendors
 This may be full compliance testing or a subset of compliance tests
 Compliance to 100BASE-T1 does not guarantee interoperability
 Transmitter requirements are well defined, the receiver is left up to the
implementer
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15. Where is the Electrical Compliance Testing Defined?
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Defined at the connector of the transmitter
Governed by channel/connector recommendations

16. Physical Layer Compliance Testing
100Base-T1 Test Modes

17. 100Base-T1 has 5 Test Modes
 Why do we have test modes?
 Allow for a common pattern to test stressful conditions across all devices
 Improves odds of interoperability
 Based off of IEEE 802.3 Clause 40.6.1.1.2
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Test Modes Tests Performed
Test Mode 1 Output Droop
Test Mode 2 Master Jitter & Clock Frequency
Test Mode 3 (optional) Slave Jitter
Test Mode 4 Distortion
Test Mode 5 Power Spectral Density & Peak Differential Output

18. Test Mode 1 – Transmit Droop
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N “+1” symbols followed by N “-1” symbols
ie: square wave
N symbol period must be greater than 500 ns
N > 34 symbols

19. Test Mode 2 – Transmit Jitter in Master Mode
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33 1/3 MHz clock
Repeating sequence of {-1,1}

20. Test Mode 3 – Transmit Jitter in Slave Mode (optional)
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33 1/3 MHz clock – timed in Slave mode
Repeating sequence of {-1,1}

21. Test Mode 4 – Transmitter Distortion Test
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PAM-3 signal with a symbol interval of 15 ns
Repeating pattern every 2047 symbols
g(x) = 1 + x9 + x11

22. Test Mode 5 – Normal Operation at Full Power
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PAM-3 symbol with a symbol interval of 15 ns
Random sequence of {-1,0,1}

23. Generation of Test Modes
 Each PHY vendor has a “backdoor” method to modify the necessary
registers to enter each test mode
 This often not publically available and the method will vary from vendor
to vendor
 You must ask your PHY vendor how to generate these test modes
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24. Physical Layer Compliance Testing
Test Detail

25. 7 Differential Electrical Physical Layer Compliance Tests
 BroadR-Reach & 100Base-T1
 Maximum Transmitter Output Droop
 Transmitter Clock Frequency
 Transmitter Timing Master Jitter
 Transmitter Timing Slave Jitter
 Transmitter Distortion
 Transmitter Power Spectral Density (PSD)
 100Base-T1 Only
 Transmitter Peak Differential Output
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26. Test Setup for PMA Compliance Testing
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Oscilloscope
DUT
“Short” Automotive Ethernet CableEthernet Test Fixture

27. Close up of Test Setup for PMA Compliance Testing
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DUT
Pair A
Differential
Signal
SMA Cables to
oscilloscope RJ45 Breakout Section

28. Maximum Transmitter Output Droop – Description
 Test Mode 1
 Measure positive and negative
droop
 Test limit is 45%
 Verify that the transmitter does
not droop more than the
specified amount
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Source: IEEE 100Base-T1 Figure 96-23

29. Maximum Transmitter Output Droop – Methodology
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1. Locate Initial Peak
(Vpk+ & Vpk-)
2. Measure Voltage after 500 ns
(Vdrooped+ & Vdrooped-)

30. Maximum Transmitter Output Droop – Methodology
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3. Calculate Droop+ & Droop-
Droop = 100 x (Vdrooped/Vpk)
4. Compare to
limit of 45%

31. Transmitter Clock Frequency – Description
 Test Mode 2
 Measure symbol transmission rate in Master Mode
 Test limit is 66 2/3 MBd +/- 100 ppm
 Verify that the frequency of the transmitted clock meets the spec limits
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32. Transmitter Clock Frequency – Methodology
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1. Measure frequency or
bitrate

33. Transmitter Clock Frequency – Methodology
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2. Compare to limit Note: 33 MHz
is half the baud
rate, since it
takes two
symbols to
create one
cycle

34. Transmitter Timing Master Jitter – Description
 Test Mode 2
 Measure RMS (root mean squared) of the MDI output jitter over at least
1 ms
 Test limit is 50 ps
 This test will verify that the jitter on the transmitted clock is within the
specified limits
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35. Transmitter Timing Master Jitter – Methodology
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1. Measure Time Interval Error (TIE)

36. Transmitter Timing Master Jitter – Methodology
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2. Create a track of TIE measurements

37. What is a track?
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A plot of each measured value in an acquisition
In this case there are 13 measured values
1
2
3
4
5
6
7
8
9
10
11
12
13
Provides insight into temporal trends of measured data

38. Transmitter Timing Master Jitter – Methodology
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3. Measure rms of TIE track
4. Compare to 50 ps

39. Transmitter Timing Slave Jitter – Description
 In normal operation as Slave
 Probe TX_TCLK or Test mode 3
 Measure RMS (root mean
squared) jitter of Slave TX_TCLK
 Test limit is 0.01 UI (150 ps)
 This test will verify that the jitter
on the signals received by the
slave is within the specified limits
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Source: IEEE 100Base-T1 Figure 96-24

40. Access to TX_TCLK
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 TX_TCLK = transmitted clock
 The spec says that each DUT must provide a means to access this
clock
 Rarely the case unless testing a PHY eval board
 ie: ECU
 Without access to the TX_TCLK this test cannot be performed
Source: IEEE 100Base-T1

41. Transmitter Timing Slave Jitter – Methodology
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3. Measure rms of TIE track
4. Compare to 150 ps 1. Measure TIE
2. Create a track of TIE measurements

42. Transmitter Distortion – Description
 Test mode 4
 Requires access to the TX_TCLK
 A disturbing sine wave is sent to
DUT and distortion is measured
 Test limit is 15 mV
 Make sure the transmitted signal
has minimal distortion so the link
partner's receiver can
interoperate with the DUT
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Source: IEEE 100Base-T1 Figure 96-21

43. Setup for Disturbing Sine Wave (Vd)
 Simulates the presence of a remote
transmitter
 If the DUT is not sufficiently linear Vd
will cause significant distortion
products to appear in the DUT output
 Frequency must be exactly 1/6 of the
DUTs symbol rate
 DUT must be subjected to Vd of
5.4 Vpk-pk
 Test can be performed with or without
Vd
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44. Matlab Code is Provided in the Spec for Peak Distortion Calculation
 Any error from ideal reference is
counted as distortion
 Removes the disturbing sine
wave and measures peak
distortion at equally spaced
phases of the symbol period
 Can be run on a separate PC
 Teledyne LeCroy embeds Matlab
code in the scope software
 Doesn’t require a Matlab license
to process
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Source: IEEE 100Base-T1

45. The Distortion Test Setup is Very Complicated
 Disturbing sinewave source,
oscilloscope, and DUT all need
to locked in frequency
 DUT has a reference clock of
66 2/3 MHz
 All test equipment takes a
reference clock in of 10 MHz
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46. Software Clock Recovery – Distortion Testing Made Easy
 Teledyne LeCroy has developed a unique software clock recovery
algorithm
 First demonstrated at UNH Plugfest in November 2016
 Removes the need to synchronize the DUT with the scope and
disturbing sine wave
 Enables test to be completed without a hardware frequency converter
board
 Makes setup simpler and cheaper
 Possible to perform testing on DUTs without access to TX_TCLK
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47. Teledyne LeCroy Simplified the Distortion Test Setup
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Matlab code is all run on
the scope
Clock recovery removes the
need for frequency locking

48. Teledyne LeCroy Test Setup for the Distortion Test
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Oscilloscope
AWG (for Vd)
DUT
“Short” Automotive Ethernet CableEthernet Test Fixture

49. Close up of Test Setup for the Distortion Test
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DUT
Pair A
Differential
Signal
SMA Cables to
oscilloscope
Distortion Test
Section
Differential Vd from AWG
Directional
couples
DUT sees Vd
but very little is
seen by the
oscilloscope

50. How Does the Software Clock Recovery Work?
 Aligns the oscilloscope’s sampled points with DUT’s TX_TCLK
 1. Find the correct frequency offset of the DUT
 Measure a reference waveform without disturbing signal
 2. Re-sampling the input data to the nominal bitrate
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51. 1. Finding the Correct Frequency Offset of the DUT
 Pattern length of
2047 bits which
repeats after
30.705 μs
 Using two zoom
windows with an
offset of 30.705 μs
the same pattern will
be found
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30.705 μs

52. 1. Finding the Correct Frequency Offset of the DUT
Measure the delta time for all edges in Zoom 1 to the correspondent edge
in Zoom 2 and calculate the average of all measurements
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∆ ∆

53. 6/7/2017Company Confidential 53
 P1 = average of
measurements
between Z1 and Z2
 P3 = offset in ns
from the ideal length
of the pattern
 P5 = offset of the
clock in ppm
1. Finding the Correct Frequency Offset of the DUT

54. 2. Re-sampling the Input Data to the Nominal Bitrate
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 First step is to add
additional points
between the
sampling points
(interpolation)
 In this example we
have interpolated
by a factor of 10
Sampling points
Interpolation

55. 2. Re-sampling the Input Data to the Nominal Bitrate
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 To increase the
frequency by 10%
we have to use
every 9th point (9,
18, 27,…) from the
interpolated
waveform
 To decrease the
frequency by 10%
it would be every
11nd point
Point for new waveform

56. Maximum Transmitter Output Droop – Methodology
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1. Calculate Distortion
2. Compare to 15 mV
3. Measure 10 phases
over the UI

57. Transmitter Power Spectral Density (PSD) – Description
 Test Mode 5
 Calculates the PSD of signal in
normal operation
 Can be performed with a
spectrum analyzer or
oscilloscope with spectrum
capabilities
 Verifies that the PSD does not
exceed the specified mask
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Source: IEEE 100Base-T1 Figure 96-25

58. Maximum Transmitter Output Droop – Methodology
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1. Calculate PSD

59. Maximum Transmitter Output Droop – Methodology
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2. Average PSD over 60 seconds

60. Maximum Transmitter Output Droop – Methodology
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3. Test against mask

61. Transmitter Peak Differential Output – Description
 Test Mode 5
 Measures peak-peak voltage during normal operation
 Measured during PSD test
 We recommend to use 10 us/div
 Verifies that the signal does not exceed maximum amplitude of
2.2 Vpk-pk
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62. Maximum Transmitter Output Droop – Methodology
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1. Measure Peak to Peak voltage
2. Compare to 2.2 V

63. Physical Layer Compliance Testing
Test Equipment Requirements

64. Test Equipment Requirements
 1 GHz Oscilloscope with at least
2 GS/s sample rate
 We recommend 10 GS/s
 Oscilloscope with Spectral
Analysis capability or Spectrum
Analyzer
 Disturbing Sine Wave Generator
 5.4 Vpk-pk at 11.11 MHz
 2 BNC cables
 2 BNC-SMA adapters
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 Ethernet Test Fixture
 2 SMA cables
 2 SMA-BNC Adapters
 1 GHz Differential Probe
 Short Automotive Cable
 Vector Network Analyzer
 For return loss and common
mode

65. Ethernet Test Fixture (TF-ENET-B)
 Fixture used for 10/100/1000
Base-T testing
 RJ45 Interface
 Breakout section
 Distortion test section
 Designed so that only DUT sees
the disturbing signal
 Need to pay attention to which
pair the signal is brought out on
the RJ45 connector
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66. Connecting the DUT to the Ethernet Fixture
 The Medium Dependent Interface (MDI) is not mechanically specified
 The tester is responsible for creating a mating fixture/cable
 This is referred to as a “Short Automotive Cable”
 This cable should be as short as possible
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67. Example of Custom Short Automotive Cables
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68. Example of Custom Short Automotive Cables
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69. Example of Custom Breakout Fixture
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70. Physical Layer Compliance Testing
Automated Compliance Software

71. Why use Automated Compliance Software?
 Automation will greatly decrease the test time
 Complete testing takes less than 10 minutes
 Complete documentation of test results
 You don’t need to be an expert to perform testing
 Software guides you through each step
 Results are fully repeatable – tested the same way every time
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72. QPHY-BroadR-Reach: Teledyne LeCroy’s Automated Test Package
 BroadR-Reach V3.2 and
100Base-T1
 Industry’s first test package
 Support for all PMA Transmitter
tests
 Only test platform to perform
software clock recovery for
distortion test
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73. Guides the User Through the Each Step
 Prompts notify user to output
correct test pattern
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 Detailed connection diagrams
ensure the proper setup

74. Fully Documented Report Automatically Generated
 Report conations:
 Test values
 Specified test limits
 Screen captures
 Can be created as:
 HTML
 PDF
 XML
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75. Fully Documented Report Automatically Generated
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76. Advanced Debugging
 Stop On Test
 User can pause testing after each individual test
 Seamlessly resume testing after debugging
 Pause on Failure
 During the test the software notify
the user if a failure occurs
 Each test can be looped to easily
perform optimization and margin testing
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77. 6/7/2017Company Confidential 77
Questions?
Bob Mart
Robert.Mart@teledynelecroy.com