Military, aerospace, and physics applications drive new MicroTCA innovations
MicroTCA is a highly versatile backplane-based architecture that is utilized in a wide variety of applications. With a high-speed connector, compact size, hot-swappability, and 99.9999 percent achievable uptime, it's a powerful architecture. Particularly in military/aerospace and physics applications, end users are asking for solutions to make the architecture faster, handle more power, provide more I/O, and meet other demands of the environment. The MicroTCA/AMC vendors are stepping up to meet these requirements.
In the mil/aero market, there have been ruggedized solutions for MicroTCA for years. Although MicroTCA.2/.3 never gained mass adoption, vendors have been using best practices for rugged rackmount and air transport rack (ATR) designs. Handling more processing power is one of the common desires for the highest-end computing requirements. With the architecture’s small size, MicroTCA at times has had limitations on using some of the powerful processors available in the market. However, new trends and innovations are changing the game. Organically, one of these issues continues to subside.
As processors become more compact and utilize less wattage, more options can be utilized in MicroTCA. In fact, there are several high-end AMCs that have been released recently (details are discussed below). The other game-changer is that vendors are utilizing more of the “tongues” of the connector to increase the power and I/O available. A typical AMC uses a single tongue with 21 pins that use about 4A each. By using a double-tongue, these pins can be used to power AMCs to over 160W theoretically, but more in the 110-120W range in practice. This opens up the AMCs to utilize processors such as the Intel Xeon E5-2648L and FPGAs such as Xilinx’s Virtex UltraScale XCVU190, with 1800 DSP slices. One example is VadaTech’s AMC594 dual channel 8-bit ADC at 56 GSPS with the XCVU190 UltraScale FPGA and 16GB of 64-bit DDR4 memory. (Figure 1.)
One may wonder if this second tongue creates a custom, proprietary solution. It does not hamper interoperability; the use of the second tongue is allowed in the specification and the pitch between slots has enough space for it. Therefore, the backplane spacing is not affected. But, sometimes these solutions will be customized to squeeze out even more performance. For example, the AMC594 has a special high-speed connector in the Zone 3 (RTM) area that plugs into a proprietary second backplane.
These types of innovations are bringing in new design wins for MicroTCA. These include:
- An unmanned airborne electronic warfare (EW) payload with a large U.S. defense prime, based on Xilinx Zynq UltraScale+ and Analog Devices AD9361. The customer started with standard commercial rackmount platforms for capability demonstrations and is now working with the vendor to create ruggedized deployable versions.
- An avionics sensor system with a major U.S. aerospace company, initially using standard MTCA chassis and modules based on Xilinx RFSoC.
- Naval countermeasures suite with a U.S. defense prime, using hardened MTCA (including ADC, DAC, and FPGA).
- High-speed (56 Gsps) data-acquisition system capable of supporting up to four channels (I/Q, dual-modularity) for optical network development, with a European partner.
It’s not just the military/aerospace market that is pushing performance; the physics labs are also driving new MicroTCA innovations.
MicroTCA, particularly MicroTCA.4 for physics, is increasingly popular in various lab environments. While we often focus on the AMC boards, the chassis are also been designed to meet a wide range of application requirements. There are many chassis platforms for the double-module-sized AMC that are used in MicroTCA.4 for physics. They are typically 7U-9U tall and provide up to 12 AMCs with redundant MCH options.
However, sometimes the labs desire smaller enclosures with fewer slots. There are also several of these in the market, but the majority are side-to-side cooled. While efficient, this airflow path requires special cabinet arrangements to support the management of the cold intake and hot exhaust. nVent/Schroff developed a front-to-rear cooled version in a 3U size for the European Spallation Source (ESS) in Sweden. The chassis offers 6 AMC slots, 4 MicroRTMs, and an optional integrated JTAG switch module (JSM).
Ioxos has developed an IFC_1410 intelligent FMC carrier for MicroTCA.4 based on Kintex UltraScale and an IFC_1420 1.8 GHz 16-bit 10 channel ADC with 5 DAC channels to the RTM. They have also introduced an I/O and synchronization MicroRTM that interfaces with the FMC carrier. DESY [Deutsches Elektronen-Synchrotron, Hamburg] developed a new four-channel piezo driver to help labs have a general-purpose piezo actuator using high voltage and high current drive. It is used in high-energy physics applications for the synchronization and special diagnostics as well as the tuning of superconducting cavities. They have been successfully installed and commissioned at the European XFEL facility especially for master laser oscillator (MLO) synchronization, electro-optical bunch length diagnostics (EOD), or pump-probe experiments. [Note: DESY will have its annual MicroTCA Workshop December 5-6, 2018, at its newly completed MicroTCA Technology Lab.]
Other boards have been developed to upgrade the performance of existing MicroTCA/AMC systems. This group includes Concurrent’s AM F5x/msd AMC based on an Intel Xeon E3-1500 v5 processor with PCIe Gen3 connectivity. Also available: An AM G6x/mds double module AMC with an optional MicroTCA.4 MicroTCA connector. It features a Xeon E3-1505M v6 processor and has direct attached storage capability. Pixus Technologies also upgraded its MicroTCA chassis to PCIe Gen3 and offers some configurations for 40GbE. Of course, there are many ongoing product upgrades in the industry for MicroTCA/AMC. (Figure 2.)
AMCs in AdvancedTCA
A fact that is often lost to those who are new to MicroTCA is that the AMCs were originally designed to be used inside carrier boards for AdvancedTCA designs. Although this design approach is not used as often, some AdvancedTCA applications would greatly benefit from the additional I/O, storage, and specialty board features of the AMCs. Alternatively, there are hybrid AdvancedTCA/AMC chassis that allow both types of boards to be plugged in a specialized chassis without requiring carriers.
Next levels of performance
A current PICMG committee is getting closer to finalizing the specification for 40GbE MicroTCA/AMC systems. In short, the group has done detailed simulation studies proving even worst-case performance for 40GbE. The group recently has developed the specialty probe cards for testing the simulations using the full interconnect path of the hardware. When the final results are complete, the specification will be updated. Some members of this group plan to do a cursory review of PCIe Gen 4 speeds as well, although this is not the primary focus of the committee.
Achieving 100G speeds would almost certainly require a connector modification, but cursory review of simulation results suggest that short paths with very high-grade PCB material and backdrilling may be able to support small to medium-sized backplanes. As PICMG is member-driven and because to a large degree MicroTCA is customer-driven, the members, the labs, and the military/aerospace community would ideally drive next-generation efforts.
MicroTCA and AMCs continue to hit new levels of performance with creative design solutions from PICMG member companies. The architecture remains a growing choice in the military/aerospace community with its SWaP advantages and vast array of options. Physics and a wealth of other applications – including banking, industrial, medical, test/measurement, communications, and more – continue to bring MicroTCA new applications and innovations. Particularly with creative use of underutilized perks of the specification, MicroTCA will continue to advance for many years to come.