Kevin Burt, of the Samtec Optical Group, explains another one of the several demos that Samtec presented at OFC 2017. In this demo, four GT 28 Gbps transceiver signals are generated by an FPGA and launched mid-board from a FireFly™ 28 G x4 optical connector system.
These 28 Gbps signals then “flyover” the board through a FQSFP twinax cable assembly, to the port, and loop back over the same path, where they are received by the FPGA. The Flyover™ QSFP28 demonstration confirms 28 Gbps performance on all four links, with zero bit errors, after having traveled over 16” (40.64 cm) of twinax cable.
This demo shows the variety of Samtec interconnects supporting the Xilinx® Virtex® UltraScale+ FPGA VCU118 Development Kit. Included in the kit is an FMC+ Active Loopback Card, which carries Samtec’s direct attach Flyover™ QSFP28.
This loopback mezzanine card was designed to be used in conjunction with the Xilinx UltraScale+ VCU118 development board, and is included in the VCU118 Development Kit. This kit is obviously available from Xilinx.
Loopback Card
The mechanical design of the loopback card is based on an elongated version of the VITA 57.4 single-width mezzanine card. This same loopback card is also available from Samtec as a stand-alone product to aid in FMC+ development environments. This product is available with Samtec’s Flyover QSFP28 Twinax Cable Assembly (HDR-19305-01-ECUE) and aluminum faceplate attached.
Flyover™ QSFP (FQSFP)
The direct-attach flyover QSFP28 cable assembly “flies” 28 Gbps high-speed signals over the PCB for improved signal integrity at cable lengths beyond ten inches.
Things you should know about the FQSFP include:
28 Gbps NRZ/56 Gbps PAM-4 high-speed performance (FQSFP Series)- Backward compatible with all QSFP cable assemblies
- Signal integrity is improved and extended by flying critical data over lossy PCB materials
- No re-timers are required resulting in reduced costs and power consumption
- Reduced PCB costs due to lower layer counts and increased material options
- High-speed signals via Eye Speed® 30 AWG 100 Ω twinax cable
- Press-fit tails provide low speed signals and power to the PCB
- Thermal dissipation is improved through power reduction and by freeing designers to place ICs in preferred locations
- Multiple end two options available
- Flyover QSFP28 DD (double density) is in development
Other Samtec products included in the VCU118 Development Kit include (all based on Samtec’s SEARAY™ high-speed arrays):
- ASP-184329-01, a 560 I/O FMC+ socket connector on the VCU118 board
- ASP-184330-01, a 560 I/O FMC+ terminal connector on the Active Loopback Card
- ASP-134486-01, a 400 I/O FMC socket connector on the VCU118 board
- ASP-134488-01, a 400 I/O FMC terminal connector the Active Loopback Card
Other links that may be of interest include:
- Flyover QSFP System brochure
- FQSFP Series cable system
- Samtec products supporting VCU118 and Loopback Card
- FMC Overview
