8B/10B Coding 64B/66B Coding - Nikhef

[Pages:29]8B/10B Coding 64B/66B Coding

1. Transmission Systems 2. 8B/10B Coding 3. 64B/66B Coding 4. CIP Demonstrator Test Setup

Sep 4, 2008

PeterJ Slide 1

Transmission system General

Data Clock

D

Q

Flip Flop

C

@ 1 Gbps = 1 ns = 20 cm

Sep 4, 2008

PeterJ Slide 2

Data Clock

Transmission system Propagation Delay

D

Q

Flip Flop

C

Unequal propagation delay

10 cm @ 1 Gbps

????

Sep 4, 2008

PeterJ Slide 3

Transmission system Clock Data Recovery

Data

Clock

Combine Clock and Data!

If there are enough edges in the data then the clock can be recovered from the data using a PLL

CDR

PLL

D

Q

Flip Flop

C

PLL

Sep 4, 2008

PeterJ Slide 4

Code Properties

1. Provide enough edges in the data to enable Clock Recovery

Sep 4, 2008

PeterJ Slide 5

Transmission system Receiver Threshold

Data Clock

CDR

D

Q

Flip Flop

C

Receiver Threshold refers to "Ground" which must be the same potential as "Ground" at

the transmitter!

Jitter!

Sep 4, 2008

PeterJ Slide 6

Data Clock

Transmission

Use Differential signalling!

CDR Icm

D

Q

Flip Flop

C

Receiver Threshold is halfway positive and negative signal

CommUosnemAoCdeCvooulptaligneg dCiaffpearecnitcoersb...etween transmitter anNdeterdmDinCatBioanlaantcthee! receiver can

result in excessive currents

Sep 4, 2008

PeterJ Slide 7

DC Balance

10 10 1

10 10 1

11 11 1

11 1?0

Define a maximum Run Length Sent equal amount of `1's and `0's (Running Disparity)

Sep 4, 2008

PeterJ Slide 8

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