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Testing 10Gbps Optical Modules: Simplify Your “Hot” Testing with Xilinx’s Zynq SoC

Xilinx Employee
Xilinx Employee
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(Excerpted and adapted from the latest issue of Xcell Journal)

 

By Lei Guan, Member of Technical Staff, Bell Laboratories, Alcatel Lucent Ireland

 

To test the thermal properties of optical modules, engineers traditionally had two choices. They could use a complicated network data generator to create high-speed (10-Gbps) links and then test the thermal properties of the optical modules; or they could utilize a so-called “thermal-equivalent” module with preset tunable voltage and current to mimic the thermal situation and evaluate the thermal properties without using any real high-speed data. Neither of these approaches is optimal. The first approach is a costly operation due to the need for a professional highspeed network data generator, while the second method is too abstract. A thermal-equivalent module cannot fully reflect the temperature variation driven by the physical switching behavior.

 

The fundamental requirement of this type of thermal testing is to stimulate the XFP optical transceiver continuously with 10Gbps data while using an IR camera to track and characterize the temperature variation. I picked the Xilinx ZC706 evaluation board as the development host, because the GTX transceivers on the main device, the Zynq-7000 SoC XC7Z045 (speed grade -2), can easily achieve single-line 10Gbps data transmission.

 

I’ve found over the course of my seven years of doing FPGA development that you can significantly reduce your design cycle by using as many Xilinx cores as possible. In this design, I kept the same strategy and started from the Integrated Bit Error Ratio (IBERT) core, which you can utilize to perform pattern generation and verification to evaluate the GTX transceivers on the Zynq SoC. Then, in order to properly route the design, I created a phase-aligned clock-distribution unit based on the Mixed-Mode Clock Manager (MMCM) core for simultaneously clocking both of the GTX transceivers on the FPGA fabric and the optical transceiver on the XFP evaluation board. Figure 1 shows the system diagram.

 

 

ZC706-Based 10Gbps Optical Module Tester.png

 

Figure 1: Block Diagram of the Zynq-Based Hot Optical Module Test System

 

 

By using Xilinx cores, together with the ZC706 evaluation board, it’s easy to build a test platform for evaluating high-speed optical transceivers. In this design, we illustrated the evaluation of a single XFP module. However, you can straightforwardly apply the design methodology to quickly build a logic core for testing multiple optical transceiver modules.

 

This blog is an excerpt. To read the full article in the latest issue of Xcell Journal, click here.

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