So, what are the roadblocks that have slowed down the imminent 5G revolution?
The delivery of true 5G bandwidth— which means faster video streaming and internet access and other new services— is simply unattainable without the utilization of higher radio frequencies.
"We have figured out a way to build a BAW device in a SAW-like process. From the industry’s vantage point, this is a miracle"
The gatekeeper or enabler to achieve these frequencies is the radio frequency (RF) filter, which is more essential than ever in accommodating the bandwidth required to unlock next-generation 5G applications such as HD video, VR/ AR, IoT, autonomous vehicles, and smart cities. These RF filters depend on resonating structures to pass signals in targeted frequencies, and the acoustic wave filters that were created for 4G do not support 5G frequencies and bandwidth. Simply put, the requirements for 5G bandwidth and power handling are beyond today’s RF filters.
As a result, there is a dire need for new RF filters that can fulfill the promise of 5G, similar to novel resonating structures that were created to facilitate the transition from 3G to 4G.
Unfortunately, the existing RF filter design process is unfavorably time-consuming. It takes months of “trial & error” to design and fine tune an RF filter in order to perfect its performance in a mobile device. And in the case of the very different requirements for 5G “trial & error” translates to delaying the promise.
This means phone manufacturers and 5G service providers are forced to bide their time—and wait patiently—until the industry unearths a process to design plenty of new RF filters quickly.
Can wireless carriers truly afford to wait for a more developed and optimized technology?
Probably not, since their roadmap is directly aligned to the mass adoption of 5G.
There is one company determined— and seemingly equipped—to speed up this process.
Resonant, a leader in the way RF filters are being designed and delivered for mobile handset and wireless devices, is fast-tracking the industry’s transition from 4G to 5G.
In a market that is hamstrung by limited design engineers and manual design tools, Resonant provides its customers—the world’s leading RFFE manufacturers— with a novel technology that increases design efficiency, reduces time-to-market, and lowers costs.
Resonant speeds RF filters to market using its Infinite Synthesized Networks (ISN®) software platform which optimizes the filter performance in software, meaning the part that is fabricated is very close to the final part, because of the accuracy of ISN . Resonant also has a deep IP portfolio of over 200 patents—50 of which are explicitly targeted for 5G. “Our software toolset allows us to design RF filters faster, cheaper, and better than anyone else in the industry,” emphasizes George Holmes, CEO of Resonant.
Using ISN, Resonant has developed its patented XBAR technology, a high-performance resonator technology for high-frequency, wide-bandwidth applications, such as 5G FR1 and FR2 devices and Wi-Fi infrastructure. XBAR is a fundamentally novel resonator—the building block of an RF filter—which was specifically designed to operate at frequencies of 3 GHz and higher, solving the bandwidth problem for 5G service providers.
We believe our software toolset allows us to design RF filters faster, cheaper, and better than anyone else in the industry
Revolutionizing the Design Process
This capability to significantly reduce time-to-market can be credited to Resonant’s design process, which is fundamentally different from traditional methods.
Typically, RF filter manufacturers design their filters through an iterative process that involves creating a design that meets ball park specifications, putting the design through the foundry, testing, tweaking the design, and then manufacturing that piece before re-testing. This process goes on through dozens of iterations, before the actual production of the filter. RF manufacturers continue with this iterative process until they have a product that meets their customer’s detailed specifications.
Now, compare that to Resonant’s methodology, which enables all the design and development through software, akin to how semiconductors are designed using electronic design automation (EDA) tools. Resonant designs RF filters by utilizing finite element modeling of both acoustic and electromagnetic properties of the filter made possible through its ISN software. “We can do millions of iterations before taking the first design to the foundry. This capability allows us and our clients to move very quickly, and develop RF filters rapidly,” explains Dylan Kelly, who joined Resonant as its COO in late 2019.
The arrival of Kelly, a prominent name in the RF semiconductor industry, is the culmination of a chain of events— through the last 24 months—that have firmly positioned Resonant as a force to be reckoned within the 5G filter market. Tracing back to 2018, when Resonant introduced its breakthrough XBAR 5G filter technology at the IEEE International Ultrasonics Symposium (IUS). At the time of the 2018 IUS, the highest frequencies demonstrated in a public domain were in the mid-20 GHz range. Resonant achieved the unthinkable. “Our resonators clocked frequencies above 50 GHz, which was unheard of,” recalls Holmes.
During the event, Resonant also vowed to launch fully functional RF filters— catering to 5G spectrum and bandwidth— at the Mobile World Congress (MWC) 2019.
Resonant did not disappoint. At the four-day MWC conference, Resonant amazed several mobile device OEMs, chip manufacturers, industry peers, and Wall Street and industry analysts, exhibiting the full performance of its unique resonator technology. By connecting an XBAR filter to a test system, Resonant showed that the signal pattern—wide bandwidth, low loss, and steep rejection of interfering Wi-Fi signals—was perfectly adept at providing performance for 5G handsets of the future.
Validation By the Largest Filter Manufacturer in the World
Within a few months of the MWC, Resonant caught the proverbial big fish as a client. Resonant secured an agreement with the world’s largest manufacturer of RF modules and filters, with nearly 40 percent market share. As part of the multi-year commercial agreement, Resonant has received a sizeable investment and will help develop several new 5G filters.
“The fact that we secured the agreement in record time—barely six months after launching XBAR technology—is pretty remarkable,” says Holmes.
So, what prompted this industry leader to partner with Resonant?
Kelly, who helped build Peregrine Semiconductor, provides a first-hand perspective as to why Resonant is becoming a go-to option for filter manufacturers. As revealed by Kelly, RF filter giants have— for a decade—been unsuccessful in their attempts to do a full-chip simulation to predict the performance of filters in real-world scenarios accurately.
Simply put, Resonant is the only company that offers an in-house simulation platform (ISN), allowing filter developers to make full-chip performance predictions. “This is the watershed moment that propels big firms to partner with us. Nobody else allows them to accurately simulate the whole chip, fab it, sample it, and put it together seamlessly,” adds Kelly.
The Benefits of Optimization to Boot
By allowing filter manufacturers to predict performance accurately, Resonant radically improves designer productivity, which in turn leads to lower costs, faster time-to-market and better performance.
Since ISN is a multi-physics design and simulation platform, the designer can visualize where the acoustic energy (of the structure) is and gather real insights into the performance of the filter. Kelly details, “Imagine knowing what is happening inside the filter and where to focus the optimization. The manufacturer can control costs this way.”
In several cases, Resonant collaborates with a client’s design team that may require assistance with complex modules with a large number of filters. To that end, Holmes candidly admits that a customer’s engineering team is its only true competition, “We do not have traditional competitors since nobody else has such a software toolset as ISN.” As for organizations that do not have their design and engineering teams, Resonant offers its Foundry Partner Program to design and develop products on their behalf.
New Advisory Board and Exciting Future
Almost becoming “a necessity” for both established and aspiring players in the RF filters segment, Resonant is just scratching the surface of the heights it wants to reach.
Backed by a group of investors, the publicly listed Resonant recently formed an advisory board, which includes Jeff Ball, the former Global Head of Semiconductor Investment Banking at JP Morgan, Rubén Caballero, ex-VP of Engineering at Apple, and Clint Brown, Director of Business Development Mobility Wireless Connectivity at Broadcom, Brian Crutcher, who had a long career at Texas Instruments including serving as CEO; Josh Jacobs who is on the board of several other companies and Luis Pineda, who headed up marketing for Qualcomm’s semiconductor business. “They see the opportunity that is represented through our hard work, and want to help us get to the next level,” says Holmes.
To Resonant, the so-called “next level” is not restricted to 5G filters. Instead, it will look to tackle the problem of 5G filters and Wi-Fi co-existing. Presently, 5G and Wi-Fi are in adjacent frequency bands with little guard band to separate them. As such, there is a need for a filter that can prevent signal bleed and allow maximum bandwidth operation. To fulfill this requirement, Resonant will develop XBAR resonators that provide the high Q factor necessary to ensure the rejection of Wi-Fi signals that operate in adjacent bands.
As part of its technology roadmap, Resonant plans to drive more innovation at the architectural level, especially with the emergence of new technology and frequency bands such as Wi-Fi6E. “Soon, various radio frequencies will have to operate with one another, and our XBAR technology is the only answer,” says Kelly. He goes on to add that by operating multiple radios simultaneously, handset manufacturers will no longer have to sacrifice bandwidth or spectrum.
Over the next few years, Resonant will also collaborate with foundries and mobile semiconductor manufacturers across the world that intend to enter the complex world of 5G filters. Holmes reveals, “We have deals in place with foundries that will either deliver products directly to the market or provide white label services.”
Resonant is convinced that it will eventually emerge as “the principal vehicle for RF filter manufactures to enter the 5G market.”