JEFF’S PICKS: C4ISR/EW Modular Open Standards Supported on 3U VPX Backplane

Jeff Child, Editor-in-Chief

Many military systems depend heavily on open standard slot-card style embedded computing technologies such as VME, CompactPCI, MicroTCA and OpenVPX. And a key piece of those system architectures are the backplanes such boards plug into. As processor and serial interconnect speeds have ramped up over the years, backplane designs have had to keep pace with designs that can handle higher speeds but also all the tricky effects that come into play at GHz level speeds and beyond.

Adding more twists to backplane complexity, new standards and technologies emerged to accommodate coaxial/RF interconnects implemented directly on backplanes and slot cards. And support for ever faster revs of Ethernet, PCI Express, Serial RapidIO brought along new challenges as well. OpenVPX in particular ushered in new varieties of backplanes supporting lengths between one and twenty-one slots. Meanwhile, there are many different profiles available for OpenVPX backplanes—such as central switch topologies, and distributed topologies and root-leaf topologies.

This month’s Jeff’s Pick section looks at backplane solutions. COTS Journal evaluated several such products on three aspects: technology leadership. The winning product is Elma Electronic’s high speed 3U VPX backplane that supports multiple functions including mixed payload modules, single board computers, switches and RF payloads for use by the DoD’s Hardware/Software Convergence Initiative (Figure 1). A unique aspect to this backplane is its support of high speed signals on all the data paths as well as leading edge VITA 67.3 connectors compatible with legacy VITA 67.1 and VITA 66.4 RF and optical I/O connectors. According to Elma, this was also the first VPX backplane with a radial slot card for timing and synchronization

Figure 1. Jeff’s Pick is Elma Electronic’s high speed 3U VPX backplane. It supports multiple functions including mixed payload modules, single board computers, switches and RF payloads for use by the DoD’s Hardware/Software Convergence Initiative.

The 3U, 12-slot backplane includes 7 slots that receive radial clock signals (Aux Clk and Ref Clk) driven independently from a radial clock timing card. The remaining 5 slots receive standard VPX bussed Aux_Clk and Ref_Clk signals. The timing card slot also supports a VITA 67.3c connector with 10 SMPM cavities. The backplane can handle the highest data rates possible with the VPX connector through its multiple data plane UTP connections at 10GBASE-KR data rates and 10GBase-KR UTP control plane connections. Four payload slots, each equipped with a combination VITA 67.3c optical and RF connector in the J2 position are also featured on the backplane. The slot 2 switch supports a VITA 67.3d connector module compatible with a payload module fitted with a VITA 66.4 MT optical ribbon connector or a VITA 67.1 RF coaxial connector.

When equipped with optical interfaces, the VPX architecture now allows data rates across the backplane far greater than any copper interconnect can be expected to achieve with the additional benefit of lower design complexity. The VPX optical interface ensures that this backplane will be able to meet all future bandwidth requirements. Also included on the backplane is a 12-cavity, VITA 67.3e connector to support an RF switch card. The new VITA 67.3 connectors allow high speed optical and RF interfaces present on payload modules to be mated and removed from the backplane. The scheme allows different types of I/O cabling routed to a slot to remain connected to the rear of the backplane to distribute interfaces. The backplane is designed to align with the DOD’s Hardware/Software Convergence Initiative, which aims to develop a common, modular hardware architecture across C4ISR and EW systems.

Elma Electronic
Fremont, CA
(510) 656-3400


…And the Runners Up:


3U and 6U OpenVPX Backplanes Available in Several Slot Configurations

Last year Pixus Technologies greatly expanded its OpenVPX enclosure offering along with new backplane configurations. The company has new 3U backplanes in 5, 9, and 18 slots and new 6U versions in 2 and 5 slots (Figure 2). The boards are compliant to the VITA 65 specification. The backplanes come with or without rear I/O connectors and are designed to cable over to Pixus power boards for VITA 62 or PICMG 2.11 power supplies. They have header options for VITA 46.11 for system management. Pixus also offers OpenVPX backplanes to VITA 66 for Optical and VITA 67 for RF.

Figure 2. These backplanes come with or without rear I/O connectors and are designed to cable over to Pixus power boards for VITA 62 or PICMG 2.11 power supplies.

Pixus Technologies
Waterloo, Ontario
(519) 885-5775


OpenVPX Backplanes Boast Signal Integrity at up to 10.3 Gbaud

Dawn VME Products’ VPX-598x Series Gen3 3U OpenVPX backplanes are designed for true signal integrity at up to 10.3 Gbaud performance (per VITA 68 backplane simulation models) (Figure 3). Supporting PCIe Gen 3 and 10 GbE (XAUI) and the most advanced Gen3 bandwidth module configurations, Dawn Gen3 backplanes offer multiple connector choices, including a high vibration option.

Figure 3. VPX-598x Series Gen3 3U OpenVPX backplanes are designed for signal integrity at up to 10.3 Gbaud performance and support PCIe Gen 3 and 10 GbE (XAUI).

Dawn uses VITA 68 S-parameter simulation models of signal paths across the backplane to insure compliance with signal integrity standards. In the simulation models a signal integrity budget is established for the backplane portion of a system. These models permit simulation of the backplane with available OpenVPX modules and connectors, so full system signal integrity can be achieved.

Using these simulations to guide the backplane designs, Dawn engineers use back drilling to remove stubs and then layout paths to eliminate impedance discontinuities. The goal is to optimize the path between any pair of transmitting and receiving chips in the systems, so communication proceeds without cross talk or other forms of interference. Dawn’s 598x Series VPX backplanes are designed to be compliant with the following released standards and December 2015 state of draft specifications: VITA 46.0, VITA 46.1, VITA 46.3, VITA 46.4, VITA 46.6, VITA 46.7, VITA 46.9, VITA 46.10, VITA 46.11, VITA 48.0(REDI), VITA 48.1(REDI Air Cooling), Vita 48.2(REDI Conduction Cooling), VITA65.0 (OpenVPX) ready. VITA 68 backplane models are available on request for system simulation.

Dawn VME Products
San Jose, CA
(510) 657-4444


Check Out Backplane Solutions Too…


Atrenne’s 10 GHz Gen-3 backplanes enable applications to run 40 Gb Ethernet, PCI Express Gen 3, Infiniband (QDR and FDR-10), USB 3.1 or other high-speed serial interconnects over the standard VPX connector. Atrenne Integrated Solutions, Brockton, MA. (508) 588-6110.


The Orbit Electronics Group offers several different model backplanes in 6U and 3U form factors. Two to 21 slots are standard, and virtually any custom performance configuration can be provided. Its VITA 67 backplane enables the use of high-speed serial switch fabric technologies. Orbit Electronics Group, Louisville, KY. (866) 319-8085.


The 100 Gbps Schroff AdvancedTCA backplane from Pentair is verified according to the design requirements of the IEEE802.3bj specifications for 100 Gbps Ethernet. The IEEE802.3bj specification defines two encoding techniques for 100 Gbps: 100GBASE-KR4 and 100GBASE-KP4. Pentair Technical Solutions, Warwick, RI. (401) 732-3770.


Trenton Systems’ HDB8228 HDEC Series Midsize Backplane supports up to eight PCI Express option cards and one dual processor. The design eliminates PCIe switch hops providing a 15.3 percent average bandwidth gain per option card slot compared to previous PICMG 1.3 backplane designs. Trenton Systems, Gainesville, GA. (770) 287-3100.


The VT072 single slot backplane from Vadatech provides a simple tool for benchtop testing of AMCs. It prevents the requirement of a full MicroTCA chassis for simple power-up and de-bug. Although the VT072 is typically used without a chassis, it comes with mounting holes for use within an enclosure. Vadatech, Henderson, NV. (702) 896-3337.


Verotec offers a wide range of standard PICMG2.0 Rev 3 compliant CompactPCI backplanes in 3U, 6U and 9U heights, 2 to 16 Slots wide. The are available in many different configurations: 32/64-bit, 33/66MHz, left or right system slot and 5V/3.3V voltages. Verotec, Manchester, NH. (603) 821-9921.