Goddard’s Mixed-Signal Application-Specific Integrated Circuit (ASIC) Group (from left to right: George Suarez, Jeff DuMonthier, and Gerry Quilligan) have joined a consortium with the Air Force Research Lab and Jazz Semiconductor to develop radiation-hardened ASICs.
Integrated circuits — the ubiquitous chips of silicon found in computers, autos, and virtually every other electronic gadget on the marketplace — may be as commonplace as fast-food restaurants, but try finding those that can not only withstand the rigors of spaceflight, but still carry out a very precise job onboard an orbiting spacecraft. It’s not easy. Gerry Quilligan, an electronics engineer and member of Goddard’s Mixed-Signal Application-Specific Integrated Circuit Group, knows this well.
That’s why he and his team have joined a consortium with the Air Force Research Laboratory (AFRL) and Jazz Semiconductor, a California-based company, to design and manufacture two particular types of space-worthy, application-specific integrated circuits (ASICs).
Unlike general-purpose circuits, such as microprocessors, mixed-signal ASICs are customized for a particular use, and therefore, help to increase the performance and decrease the size and power needs of an electronic device. Virtually all spacecraft platforms and instruments rely on them.
Needed for Time-of-Flight Applications
In this case, both of Quilligan’s chips would digitize amplitude and time-of-flight signals; in other words, measure the size of a packet of photons along with the time it takes to reach a detector while traveling over a varying distance — an important capability for three-dimensional imaging, autonomous landing and hazard avoidance, and laser communication.
Currently, Goddard scientists must rely on external “off-the-shelf” parts, which, in most cases, are not designed for exposure to space radiation. In fact, only a few companies in the nation actually manufacture “radiation-hardened” circuits that carry out these very precise jobs. Quilligan hopes to end the dependence on these few companies, advance the state-of-the art, and acquire the ability to tailor integrated circuits to scientists’ needs.
He says he’s well on the way.
One of his circuits will be able to measure time intervals with a sensitivity of 33 picoseconds, which is 33 million millionths of a second. “That would push the boundaries,” Quilligan said, referring to the so-called Multi-Channel Charge Amplifier Time of Flight circuit. “That is state of the art,” not only for radiation-hardened time-of-flight circuits, but even those developed for ground-based use.
Under the partnership, Quilligan and his team will design and lay out the circuits, equipping each with 16 independent channels that can be scaled up to at least 64 channels in the future. AFRL, meanwhile, will provide unique radiation-modeling design tools and Jazz Semiconductor will manufacture the circuits on a multi-product wafer (MPW), also subsidized by the Air Force. Because circuit fabrication costs are high, the MPW provides a relatively inexpensive way to manufacture several products on a single silicon wafer. This is especially ideal for researchers who need smaller batches for testing purposes. Quilligan hopes to have chips by October.
“We get low-cost manufacturing and design tools,” Quilligan said, “and they get feedback on performance.” What they all get — at least that’s the goal — are “real world circuits that will fly,” he said.
Goddard technologists win new work, secure follow-on funding to mature new technologies, formulate concepts, and validate new instrument concepts in flight demonstrations — successes that benefit Goddard and the scientific community as a whole.