Transcript OIF Overview

Characterizing 11G Long Reach CEI Channels
John Mitchell
Winchester Electronics
Agenda
Characterizing 11G Long Reach CEI Channels
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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
What is CEI?
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Next Generation Common Electrical I/O Project
Will support various higher level interfaces
including:
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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.
What is CEI?
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Four versions are defined:
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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.
Typical Long Reach Application
Backplane
Total Transmission Line
Length up to 1 meter.
Transceiver
Plug-in
Card A
Transceiver
Plug-in
Card B
Reference Model
Driver
Characteristics
Channel
Characteristics
Receiver
Characteristics
Long Reach Issues
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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
How to characterize the channel?
Time Domain
•Pattern dependent
•Eye may be closed
•Can signal conditioning help?
Frequency Domain
•How much loss is too much?
•How does this relate to the time domain?
•Can signal conditioning help?
Pulse Response Method
H(ω)
Frequency Domain
Interpolate
Extrapolate
DUT
Channel
Measurement
H(ω)
S-Parameters
Channel Response
iFFT
Characterize
Tx(t)
H(t)
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Time Domain
Transmit Pulse
Rx(t)
Amplitude
=
Channel Response
Total Channel Distortion
Jitter
Pulse Response
Thru Channel and Crosstalk Channels
Input Pulse
Input Pulse and Channel Response
Pulse Response Analysis
C0
•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
C+1
C+2
C-1
C+3
C+4
Drivers and Receivers are not Perfect
Driver will jitter pulse in time
Receiver may not sample at peak
C0
C+1
C+2
C-1
C+3
C+4
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
Crosstalk must be Added
Thru and Crosstalk Channel Pulse Response
Statistical Calculations on Measured Data
Pulse
Response
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These calculations can be
automated and incorporated into
test equipment or Matlab program
Data
Pattern
Statistics
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Driver
Jitter
Statistics
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Receiver
Sampling
Statistics
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Statistical
Data
Eye
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 1e15
Courtesy of Anthony Sanders (Infineon Technologies)
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
Technology Demonstrations at Supercomm
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Active test set-up in OIF Booth
Passive test set-up on Winchester Booth
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Hall C3 - Booth #11831