SI and EMI performance comparison of standard QSFP and flyover QSFP connectors for 56+ Gbps applications

In this paper, signal integrity (SI) and EMI aspects of a novel Flyover Quad Small Form Factor Pluggable (Flyover QSFP) connector is compared to a traditional QSFP connector which are used in 28/56 Gb/s applications. The flyover technique can overcome the limitation of high insertion loss associated with standard surface mount QSFP connectors that use PCB Microstrip traces. In flyover QSFP, substituting 7.5 cm PCB traces with 15 cm twin-ax cables results in at least 7 dB insertion loss improvement at 40 GHz. To study the SI and EMI performances of FQSFP in comparison with standard QSFP, two test vehicles were designed, fabricated, and tested. The return loss, insertion loss, and total radiated power (TRP) of both standard QSFP and flyover QSFP connectors are obtained up to 40 GHz. Based on the results, it is shown that flyover QSFP interconnect exhibits better SI performance due to the lower loss in comparison to the standard QSFP. When the same power is applied to both connectors, similar TRP performance is measured at most of the frequencies with differential excitation.