1Gbps optical link demonstration

Sourav DeR. Manivasakan Anil Prabhakar

IIT Madras

INO Collaboration Mtg, IIT Madras

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Objective

To demonstrate a point to point 1Gbps communication link over virtex 5 ml507.

To demonstrate a single node to multiple node communication link of same speed.

To design a multiple point to single point communication link.

Performance analysis of the link by eye diagram analysis.

2 March 2015

INO Collaboration Mtg, IIT Madras

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Xilinx virtex 5 ml507

2 March 2015

SFP module

FPGA

INO Collaboration Mtg, IIT Madras

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Xilinx Virtex 5 ml507

ML507 is an FXT platform that supports RocketIO GTX transceivers (up to 3.125 Gbps). Assume 4.5 Mbps from each RPC (1x16) x (1x32) x 4.5 Gbps = 2.3 Gbps We will need 10 servers for each half module

Clocking-Programmable system clock generator chipExternal clocking via SMAs (two differential pairs)

2 March 2015

INO Collaboration Mtg, IIT Madras

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Experimental Setup

2 March 2015

Tx and Rx through SMA ports on the Virtex boards

INO Collaboration Mtg, IIT Madras

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Challenges

Pre-emphasis of the transmitter to desired level.

Design the equalization block of the receiver according to the communication link.

Transmitter and receiver clock synchronization and frame detection.

2 March 2015

INO Collaboration Mtg, IIT Madras

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Incorrect Pre-emphasis Effect

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INO Collaboration Mtg, IIT Madras

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Receiver Equalization

There are two types of equalization techniques that can be implemented in the block.

Continuous Time Linear Equalization and Decision Feedback Equalization

Decision Feedback Equalization has been used.

DFE automatically adapts to time-varying properties of the communication channel.

2 March 2015

INO Collaboration Mtg, IIT Madras

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Receiver Equalization

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INO Collaboration Mtg, IIT Madras

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Effect of Incorrect Equalization

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INO Collaboration Mtg, IIT Madras

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Implementation of correct DFE

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Performance Analysis of Communication Link

Performance analysis of the communication link is done by calculating Q- factor and estimating BER from Q-factor.BER= (½)erfc(Q/ 1.414)

Configuration:1. Point to Point Link.2. Single Transmitter and Multiple Receiver.3. Multiple Transmitter and Single Receiver.

2 March 2015INO Collaboration Mtg, IIT Madras

INO Collaboration Mtg, IIT Madras

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Point to Point Communication Link at Different Data rate

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500 Mbps

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INO Collaboration Mtg, IIT Madras

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1Gbps

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INO Collaboration Mtg, IIT Madras

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Estimation of BER from Q-Factor

Data Rate Q Value BER Estimation

500 Mbps 6.73 8.5 E -10

750 Mbps 6.53 3.8 E -10

1 Gbps 6.41 7.5 E -09

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INO Collaboration Mtg, IIT Madras

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Multiple Tx to Single Rx

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INO Collaboration Mtg, IIT Madras

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Single Tx to Multiple Rx

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INO Collaboration Mtg, IIT Madras

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Estimation of BER from Q-Factor

Network Configuration

Q Value Estimation of BER

Single Transmitter multiple Receiver

5.4 3.44 E-06

Multiple Transmitter single Receiver

6.1 1.2 E -09

2 March 2015

Tx through SMA, T-splitter, Rx also on SMA

INO Collaboration Mtg, IIT Madras

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Future Work

Timing synchronization

Optical Rx (Tx is working)

Live demonstration with (1x16) x (1x32) splitters

RPC DAQ v3 board design SFP instead of Wiznet+RJ45

2 March 2015

Physical layer design

Aggregate data from two rows of 16 RPCs each

Can support up to 4.5 Mbps of data from each RPC