March 12, 2024
The development of 3D reflector microchips will enable ever smaller devices to operate at the higher frequencies required by 6G technology.
Image: Ryan Young/Cornell University
The next generation of wireless communications not only requires higher frequencies and more bandwidth, but also a little extra time. The new chip adds the necessary time delay so that signals sent across multiple arrays align to a single point in space without collapsing.
Most of today’s wireless communications, such as 5G phones, operate at frequencies below 6GHz.
Technology companies have been aiming to develop a new wave of 6G cellular communications that use frequencies above 20 GHz, where there is more available bandwidth and more data can flow faster. 6G is expected to be 100 times faster than his 5G.
However, one important factor is how the data is relayed, as data loss in the environment increases at higher frequencies. Rather than relying on a single transmitter and a single receiver, most 5G and 6G technologies use a more energy-efficient method: a series of phased arrays of transmitters and receivers.
“Every frequency in the communications band has a different time delay,” Govind said.
“The problem we are addressing is decades old: transmitting high-bandwidth data in an economical way and ensuring that the signals on all frequencies align at the right place and time. .”
“It’s not just about building something with enough delay; it’s about building something with enough delay that there’s still a signal at the end,” said senior author and engineering professor Alyssa. Apsell said.
“The secret is that we were able to do it without incurring huge losses.”
Govind worked with postdoctoral fellow and co-author Thomas Tapen to design a complementary metal-oxide-semiconductor (CMOS) that can tune time delays with a phase resolution of 1 degree over an ultra-wide band of 14 GHz.
“Our design objective was to pack in as many of these delay elements as possible,” Govind said. “To route the signal, he wraps it around a three-dimensional waveguide, from which it reflects the signal and causes a delay, rather than spreading a long wavelength wire laterally across the chip.”
The team designed these 3D reflectors to be strung together in series to form a “tunable transmission line.”
The resulting integrated circuit occupies a 0.13mm2 footprint, which is smaller than a phase shifter, but nearly doubles the channel capacity, and therefore data rate, of a traditional wireless array. By increasing projected data speeds, the chip will be able to provide faster service and deliver more data to smartphone users.
“The big problem with phased arrays is the tradeoff between making these things small enough to fit on a chip and maintaining efficiency,” Apsell said.
“The answer that most of the industry has come to is, ‘You can’t do a time delay, so you’re going to do a phase delay.’ And that fundamentally limits the amount of information that can be sent and received.
“I think one of our key innovations is actually asking the question, do we need to build this way?” Apsel said. “If you can increase channel capacity by a factor of 10 by changing one component, that’s a very interesting transformation for communications.”
