Small satellites, big business
As the small satellite space race takes off, Akash Systems, is set to send GaN-on-Diamond systems into orbit, reports Rebecca Pool.
US-based CubeSat developer, Akash Systems, has started 2018 with a bang, raising a massive $3.1 million in seed funds to accelerate delivery of its shoebox-sized satellites, based on GaN-on-Diamond RF power amplifiers.
The funds come at a time when worldwide data demand is fast outstripping the bandwidth provided by today's satellite communications infrastructure. Meanwhile, technology advances have pushed satellite services beyond Internet, television and GPS navigation, unleashing imagery-rich and data-heavy applications from aeroplane tracking to pollution monitoring.
Crucially,CubeSats and other miniature satellites are already slashing the cost of commercial satellite. And GaN-on-Diamond is set to take these plummeting prices even lower.
"Historically, satellite makers have required a very big satellite to provide kilowatts of power but now we can squeeze that tremendous amount of power into a CubeSat," says Akash Systems co-founder and chief executive Felix Ejeckam. "This means we can deliver new features and capabilities in a small satellite, which is a key reason satellite suppliers are switching over."
However, today's small satellites use GaN-on-SiC power amplifiers, which means power and speed come at a cost; heat. While such GaN-based HEMTs can ideally reach 40 W/mm RF power at 10+ GHz frequencies, thermal heating restricts power densities to some 10 W/mm. But GaN-on-Diamond can make a difference.
According to Ejeckam, diamond, with its high thermal conductivity, removes the heat in an amplifier up to four times faster than any other substrate on the market today. And as the chief executive points out, today's satellite suppliers do not want to expend resources cooling power amplifiers.
"Today's satellite suppliers would like amplifiers that can operate at higher ambient temperatures without the need for cooling," he says. "[Using GaN-on-Diamond], the logistics, heaviness and size of equipment that comes from having to cool an amplifier down simply goes away."
What's more, Ejeckam is adamant that the GaN-on-Diamond power amplifiers that his company is already supplying to market do not cost more than the GaN-on-SiC equivalent. "[GaN-on Diamond] devices are actually cheaper," he asserts. "We are happy to go with the prevailing dollars per watt, that a customer wants. And our amplifier is also smaller and has these additional benefits."
Indeed, in the months that Akash has been supplying its power amplifiers, demand has, as Ejeckam puts it, been 'overwhelming'.
"We cannot meet demand and literally cannot make enough power amplifiers," he says. "Everyone wants what we can make and more."
CubeSats from Akash Systems are scheduled to reach the market in 2019.
To get the full benefits of GaN-on-Diamond, satellite suppliers are designing the power amplifiers into systems, rather than simply swapping these components with existing devices. And right now, demand is coming from suppliers of small, commercial Low Earth Orbit satellites as well as the manufacturers of larger geostationary satellites, keen to remain competitive.
"The GEO suppliers are feeling threatened by the LEO [companies] and want to make these satellites smaller, cheaper, more powerful and as effective as possible," points out Ejeckam. "Their existing business is not expected to decline, but [performance] requirements are getting tougher and tougher every year, so these suppliers are looking for new technologies."
But Akash Systems' key challenge is to ramp up amplifier production to meet the burgeoning demand, while developing CubeSat systems that are scheduled to reach market next year. To this end, the company is working closely with foundries, and devices are being fabricated on 100 mm GaN-on-Diamond wafers. As Ejeckam says: "We are still happy with 100 mm wafers."
But burgeoning demand or not, it's no secret that the marketplace for small satellites is crowded with more and more so-called space-start-ups getting ready to launch new systems. Figures from Nanosatellite - the world's largest database of small satellites - reveal that in 2016, launches came in at 88, rocketed to 295 in 2017 and are expected to reach 703 come 2023.
So how does Akash Systems intend to compete in this rapidly growing space? Ejeckam is blunt. "We have this underlying, fundamental technology that nobody has," he says. "This distinguishes us greatly from everyone else."
