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Characterizing 11G Long Reach CEI Channels

Characterizing 11G Long Reach CEI Channels. John Mitchell Winchester Electronics. Agenda. Introduction to CEI Definition of a channel How to characterize channel performance Accounting for the driver, receiver and data An eye pattern based on statistics Conclusions.

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Characterizing 11G Long Reach CEI Channels

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  1. Characterizing 11G Long Reach CEI Channels John Mitchell Winchester Electronics

  2. Agenda • Introduction to CEI • Definition of a channel • How to characterize channel performance • Accounting for the driver, receiver and data • An eye pattern based on statistics • Conclusions Characterizing 11G Long Reach CEI Channels

  3. What is CEI? • Next Generation Common Electrical I/O Project • Will support various higher level interfaces including: • SFI (SERDES to Framer Interface) • SPI (System Packet Interface) • TFI (TDM-Fabric to Framer Interface) • Higher Density and/or lower cost interfaces for data rates up to 10+Gbps.

  4. What is CEI? • Four versions are defined: • A 6G+ short reach link • 0 to 200mm link with up to one connector • Data lane(s) that support bit rates from 4.976 to 6+Gbps over Printed Circuit Boards. • A 6G+ long reach link • 0 to 1m link with up to two connectors • Data lane(s) that support bit rates from 4.976 to 6+Gbps over Printed Circuit Boards. • An 11G+ short reach link • 0 to 200mm link with up to one connector • Data lane(s) that support bit rates from 9.95 to 11+Gbps over Printed Circuit Boards. • An 11G+ long reach link • 0 to 1m link with up to two connectors • Data lane(s) that support bit rates from 9.95 to 11+Gbps over Printed Circuit Boards.

  5. Typical Long Reach Application Backplane Total Transmission Line Length up to 1 meter. Transceiver Transceiver Plug-in Card A Plug-in Card B

  6. Reference Model Driver Characteristics Channel Characteristics Receiver Characteristics

  7. Long Reach Issues • Significant loss at high frequency • Significant loss dispersion over required bandwidth • Numerous transmission line transition points may cause reflections • Potential Skew Issues • Potential Crosstalk Issues • Various signal conditioning options

  8. How to characterize the channel? Time Domain Frequency Domain • Pattern dependent • Eye may be closed • Can signal conditioning help? • How much loss is too much? • How does this relate to the time domain? • Can signal conditioning help?

  9. Pulse Response Method H(ω) H(ω) Frequency Domain Interpolate Extrapolate DUT Channel Measurement S-Parameters Channel Response iFFT Characterize Total Channel Distortion Tx(t) H(t) Rx(t) Amplitude * = Time Domain Jitter Transmit Pulse Channel Response Pulse Response Thru Channel and Crosstalk Channels

  10. Input Pulse

  11. Input Pulse and Channel Response

  12. Pulse Response Analysis • C0 cursor is placed at peak • Pre and Post cursors are placed at baud spaced intervals • Pre and Post cursors represent distortion • Relationship between C0 and the sum of all other cursors can be used to characterize the channel • The probability of cursors causing distortion can be determined based on the data pattern being transmitted on the channel C0 C+1 C+2 C+3 C+4 C-1

  13. Drivers and Receivers are not Perfect Driver will jitter pulse in time Receiver may not sample at peak C0 C+1 C+2 C+3 C+4 C-1

  14. Each Cursor has a Range of Values • Probability of driver and receiver behavior can be determined • This will set bounds on possible cursor positions for a given number of bits

  15. Crosstalk must be Added

  16. Thru and Crosstalk Channel Pulse Response

  17. Statistical Calculations on Measured Data Pulse Response These calculations can be automated and incorporated into test equipment or Matlab program Data Pattern Statistics + Driver Jitter Statistics + Receiver Sampling Statistics Statistical Data Eye + =

  18. Statistical Data Eye • Each contour line represents the statistical eye opening for a given number of bits • The most red eye in this case represents BER of 1e-15 Courtesy of Anthony Sanders (Infineon Technologies)

  19. Conclusion • OIF is developing a new method to characterize interconnect channels • Basis for characterization is measurement with VNA (complete and accurate) • The new method accounts for statistical variation in the data pattern and performance of driver and receiver • Results are in familiar Time Domain format and easy to interpret

  20. Technology Demonstrations at Supercomm • Active test set-up in OIF Booth • Passive test set-up on Winchester Booth • Hall C3 - Booth #11831

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