One of the most popular interfaces in the FPGA world is FMC. This has recently been expanded to FMC+. The new VITA 57.4 standard defines two new connectors. Combined, they offer 32 full-duplex channels running at 28 Gbps.
However, the current generation of FPGAs and MPSoCs have transceivers supporting data rates in excess of 32 Gbps. Why? Emerging protocols – including PCIe Gen 5 and JESD204C – will run at 32 Gbps.
Engineers developing solutions using 32Gbps+ protocols need interconnect solutions and test platforms they can depend on. While FMC+ is defined for 28Gbps, Samtec specifies the SEARAY™ to 56 Gbps PAM4. So, can FMC+ work at 32 Gbps?
Ottawa-based Fidus Systems Inc. recently announced the Fidus Mantyss™-32G. Based on the Xilinx® Zynq® UltraScale+™ MPSoC, this versatile product combines multiple Arm® processors and 32 Gbps high-speed transceivers to further accelerate prototyping of the latest generation of ASICs on Synopsys HAPS Prototyping Solutions.
Next-gen ASICs, FPGAs and SoCs will leverage PCIe Gen 5. Likewise, interfacing to JESD204C ADCs/DACs are a must for wireless communications application like 5G infrastructure and SIGINT.
The Fidus Mantyss-32G, a 48-layer CCA, is architected using the highest speed grade Xilinx Zynq UltraScale+ ZU19EG MPSoC. Additionally, it features multiple expansion ports that use Samtec interconnect solutions like VITA 57.4 FMC+ and FireFly™ Micro Flyover System™.
32 Gbps Test Set-up
Fidus worked with Samtec to identify the best solution for running 32 Gbps data rates on the Fidus Mantyss-32G. Fortunately, Samtec has multiple loop-back options for popular Samtec interconnect.
Samtec’s VITA 57.4 FMC+ HSPC Loopback Card provides FPGA designers an easy to use loopback option. It can be used for testing transceivers on any FPGA development board or FPGA carrier card like the Fidus Mantyss-32G.
In addition, Samtec also offers the FireFly™ Loopback Cable Assembly (P/N HDR-190945-01-ECUE) It can be used for high-speed verification for the FireFly two-piece connector set.
Fidus attached both Samtec loopback solutions to a Fidus Mantyss-32G. The final test set-up is shown below.
32 Gbps Test Results
Each 32 Gbps transceiver loopback path was tested using the IBERT functionality of the Xilinx Vivado Design suite. Most importantly, all links were confirmed to be running error free before eye diagrams were captured. Moreover, minimal signal conditioning was used.
The top 8 lanes are looped back at a Samtec Firefly connector set. The bottom 8 lanes are from the VITA 57.4 FMC+ HSPC Loopback Card. As a result, the test data is shown below.
What does this test prove? Under the right conditions using optimized SI techniques, both Samtec FMC+ and FireFly connector sets can achieve 32 Gbps operation.
The Fidus design team skillfully combined SI support from Samtec with leading-edge PCB design techniques to accomplish this task. Samtec provided Fidus with complex, high-speed connector models and recommended BORs, Fidus’s Signal Integrity team then used these models to fully simulate and optimize the complete channel
The Fidus PCB team utilized decades of high-speed know how to identify the best combination of complex laminates, stack-ups and complex technologies to optimize the performance of the Fidus Mantyss-32G.