Military satellite payload performance demands drive rad-hard electronics
Increased ISR and communications bandwidth demands for military satellites are forcing rad-hard electronics designers to pack more and more performance into smaller form factors. Meanwhile, uncertainty reigns in terms of funding for space-based programs out of the DoD and NASA.
Battlefield success or success in any endeavor for that matter often is dependent on who has the best intelligence. Even as the U.S. military starts scaling back troop deployments in the Middle East, they will continue to increase their Intelligence, Surveillance, and Reconnaissance (ISR) operations to stay one step ahead of enemies and even allies.
Powerful ISR payloads enabled by the supercomputing performance of modern processors and computers are being developed and deployed in manned and unmanned ground, sea, air, and especially space platforms. All of these platforms have requirements demanding more and more performance with less power in ever-shrinking footprints, but the environmental challenges of space add difficulty as each component must be sufficiently radiation hardened, or rad hard, to survive for decades.
“Military space customers are facing pressures similar to commercial customers when it comes to performance requirements,” says Ken O’Neill, Director of Space Marketing at Microsemi SOC Products Group in San Jose, CA. “Systems need ICs to have higher functionality and higher performance without consuming excessive power. They essentially want to have more functionality in less space.
There is demand for more processing, more bandwidth, and more memory for increased on-orbit storage, says Chuck Tabbert, Vice President of Sales and Marketing at Ultra Communications in Vista, CA. The increased performance requirements will be realized by making use of advanced FPGAs and multicore processors. There also seems to be a strong road map for increasing processing bandwidth by moving more toward fiber-optic technology, Tabbert says. “We are getting requests from customers for 40 Gb box-to-box connectivity over fiber because you can’t move that kind of bandwidth over copper.” Tabbert’s company designs fiber-optic rad-hard transceivers and just patented a rad-hard 40 Gb transceiver.
“The advanced technologies are driving our creativity when it comes to managing all the heat and power they generate as we jam more and more performance into 5- and 10-pound bags,” says Tony Jordan, Director of Standard Products at Aeroflex Colorado Springs in Colorado Springs, CO. “Satellite weight has always been [an] issue. Every pound is tens of thousands of dollars of boost launch cost.”
“Payload performance demands drive most of the technological change in satellites today,” says Peter Milliken, Director of Semi-Custom Products at Aeroflex Colorado Springs. Applications such as signals intelligence and visual imaging are where the technology is going, he adds.
“There is increased pressure on all programs to deliver to the field new technology and on time. However, the debt problem worldwide is restricting satellite growth,” Jordan says. “If not for the debt, the bandwidth demand would be insatiable. Governments and satellite designers want to bring more capability to bear for satellite payloads, transponders, radios, and add features with the capability for remote sensing to have constant ‘eyes in the sky.’ While I cannot comment on classified programs, they continue to drive technology and are probably under less funding pressure, as they are not as visible as unclassified programs,” he adds.
A great example of a Department of Defense (DoD) satellite using existing and new technologies together is the Lockheed Martin Advanced EHF satellite, which “uses eight RAD750s (Figure 1) for the payload with two RAD6000s used on the bus,” says Vic Scuderi, Manager of Satellite Electronics for BAE Systems in Manassas, VA. It is a more conservative satellite design that takes a stable bus architecture and marries it with a newer generation payload. The RAD6000 adds stability at the bus level, while the RAD750 provides the necessary processing horsepower for the demanding payload requirements.
There are military space programs (tactical programs, short response time programs) needing parts that combine reprogrammability and high functionality with sufficient radiation tolerance for the mission (usually short duration and Low Earth Orbit), O’Neill continues. “Shorter missions have lesser radiation requirements. Our RTAX-DSP parts are seeing adoption in systems [that] need the additional signal processing horsepower afforded by built-in radiation tolerant multiply-accumulate blocks. The blocks provide higher density, giving users built-in DSP capability in the FPGA to perform signal-processing functions such as Fast Fourier Transforms (FFTs) more efficiently.”
There also seems to be a big thrust toward affordability, to scale back some of the requirements to be more cost efficient without compromising reliability, Tabbert says. There might be times where integrators will take a little risk to lower costs, he adds.
Reliability still important
While many terrestrial programs leverage commercial technology right off the shelf, designers of space systems do not often have that luxury. Unlike in a ground vehicle or aircraft, electronic components that are used for satellite control must work for 15 years without failing – as satellites can’t go back “to port” for maintenance. Suppliers must be able to demonstrate to government customers that they have the legacy and stability in producing rad-hard electronics, as they will need to support programs that last for decades.
“High performance components are meeting the payload needs but do not need to be as durable as satellite Command Data and Handling (CD&H) electronics, which keep the satellite on orbit,” Milliken says. “CD&H devices require more radiation immunity than typically comes in an ASIC technology such as our UT90nHBD, which is payload centric (Figure 2). We also continue to still sell 5-volt technology that is used in legacy platforms of our aerospace and defense customers.”
BAE Systems products typically work without ground prevention for as long as 15 years because they are designed to be rad hard from the ground up, Scuderi says. “Integrators that decide to go with commercial products and upscreen them to be rad hard are taking a risk when it comes to reliability. While the importance of flight heritage cannot be overemphasized, higher-performance payload applications demand higher processing and throughput. Our government customers are mindful of the need to mature this technology for space. Our processor technology road map has been funded to develop newer technologies with smaller and smaller feature sizes that translate directly to lower power and higher MIPS [Millions of Instructions Per Second]. Our newest 45 nanometer technology is a good example of this trend.” For more on BAE Systems’ rad-hard components, see Sidebar 1.
“Our hybrid DC/DC converter and filter customers are increasingly requiring a more complete capability in the components they procure,” says Matthew Twitchell, Product Manager – Interpoint Space at Crane Aerospace & Electronics in Everett, WA. “The military space and commercial space markets have shifted from a narrow list of radiation requirements to requiring guarantees in several areas relating to radiation or a summation of effects. Some of these areas include analysis and measured test results for lower dose rates, which are more representative of the space environment – single event upsets, proton fluence, and some higher total radiation doses. These requirements drive the design methods and technologies used in creating the latest products as well as the need to conduct further testing and analysis for existing offerings.”
“The design trend overall is moving toward higher levels of integration, including the use of radiation-guaranteed ICs and inherently rad-hard device technologies, such as SiC, SOI [Silicon on Insulator], and GaN,” says Jay Kuehny, Principal Engineer, Crane Aerospace & Electronics. “While higher levels of integration serve lower cost and higher densities, great care must be taken to ensure robustness to single event effects. This often includes long design and qualification cycles and can result in high levels of redundancy, ultimately driving a more costly solution. To support the growing trend of longer-life spacecraft, these ICs must also be available to support program durations measured in decades rather than years. With the military and space markets extending program life expectations and the desire for proven technology, we have noted a slower rate of adoption for newer designs.”
Crane’s latest Interpoint converter product is the MFP Series point-of-load converter, Twitchell says. This device is guaranteed to 100 krad total radiation dose, Enhanced Low Dosed Radiation Susceptibility (ELDRS) level of 30 krad, to an LET of 85MeV-cm2/mg for single event effects and is Space Qualified to Class K per MIL-PRF-38534 on a Defense Logistics Agency’s (DLA’s) Standard Microcircuit Drawing (SMD) number.
Other rad-hard offerings
VPT engineers have added a 15 A point-of-load DC-DC converter to their family of power conversion products for space applications. The SVGA0515 Series is a non-isolated, regulated buck converter, which steps down the voltage at the point of use in a distributed power system. It is qualified to MIL-PRF-38534 Class H and Class K by the Defense Logistics Agency and is targeted for power systems used on GEO, MEO, LEO, and deep-space applications.
The latest rad-hard FPGA offering from Xilinx is the Virtex-5QV FPGA, built on the second-generation ASMBLTM column-based architecture of the Virtex-5 FPGA family. It has protection from Single Event Upsets (SEUs), Single Event Transients (SETs), Single Event Latchup (SEL), and high Total Ionizing Dose (TID) – 1Mrad (Si). The device has 131,072 logic cells, is an integrated high-speed SERDES solution for space, and has 18 channels of >3 GHz multi-gigabit serial transceivers enabling high bandwidth for chip-to-chip, board-to-board, and box-to-box communications. For more rad-hard suppliers, see Sidebar 2.
Funding for space
Despite the increasing demands for performance on the payloads, funding for space programs from the DoD and other government agencies remains uncertain or flat at best for the next few years.
“What we’re observing in the U.S. DoD market is a lot of uncertainty about when funding for procurement will be released, which makes it harder to forecast business,” O’Neill says. “The uncertainty also causes hesitation on the contractor’s part when releasing purchase orders. However, design activity seems to be relatively unaffected and remains constant with substantial activity going on in various programs.”
“DoD funding trends have generally slowed many existing space programs [that] were previously very active in the procurement phase,” Twitchell says. “This has translated into some shifting in the timing but has not yet materialized into cancelations. Recent DoD funding shifts have influenced the market by slowing the expected growth rates with our traditional customers. While the medium- to short-term growth rates seem to have flattened, it is expected that the commercial market and new partners in the space arena will begin to increase demand for space-qualified components. While this trend or shift to the commercial approach looks promising, the requirements for testing, analysis, and guarantees for product performance continue to increase. These [three] factors in combination look to provide us a very interesting next few years in the space market.”
“DoD budgets are not yet beginning to slow on programs, because procurement for programs to be released in 2012, 2013 has been completed already,” says Minal Sawant, Segment Marketing Manager at Microsemi. “The effects of budget cuts will be seen in 2014 and beyond, since programs are being put on hold.”
“Budget cuts have impacted DoD and NASA missions, but we are fortunate that our business model includes a strong mix of commercial satellite opportunities as well,” Twitchell says. “The commercial market has been holding steady across the international scene, and we have benefitted from this stability. Secondary payloads for DoD applications will also pave the way for government and commercial satellite ventures that are able to bring newer technologies into space.”