DesignCon 2022 Schedule Builder

The multitude of Electrical/Optical interfaces, such as QSFP modules, lead to the accumulation of EMI in larger routers. Levels far above the level of an individual module are reached, possibly causing unacceptable levels of EMI. To predict the EMI level of a router-like system, the EMI of individual modules needs to be measured for selecting acceptable modules. However, it is difficult to predict the level of radiation in a fully implemented system because different vendors and users have different test methods to quantify the radiation levels of modules. Neither unified test methods nor universal platforms exists. We aim to solve this problem by developing an open hardware/open software reference platform for evaluating EMI in optical modules. This platform enables reproducible measurements at data rates of up to 800 Gbit/sec. By well-designed shielding and controlled interfaces only the radiation from the module is measured. This is be accomplished by • Operating the optical module under test in a loopback mode • Providing a well shielded enclosure that only allows radiation from the optical module under test • Including a reference source having a defined radiation level that allows to verify the EMI test chamber or mode stirred chamber setup prior to the measurement of an optical module • Providing interchangeable sockets for different optical module form factors without affecting final system performance • Controlling parameters such as temperature, supplied voltage etc.

Takeaway

Repeatable and comparable EMI measurement of different optical modules, such as QSFP, QSFP-DD and OSFP, is made possible by the proposed optical module evaluation platform and set of measurement guidelines. Shielding and interface design suppresses other radiation. The design allows to only measure the radiation of the QSFP/OSFP module.