In a recent interview, CNBG CTO Justin Clark discussed how engineers tackled supply chain challenges stemming from limited component suppliers.
As part of the 5G standard in Release 15, 3GPP introduced the use of millimeter wave (mmWave) frequencies for high-bandwidth applications. While mmWave technology didn’t gain traction in mobile devices due to its limited range, it found a niche in venues like stadiums and for fixed-wireless access (FWA) home internet connections.
Designers and manufacturers of mmWave radios face unique obstacles due to the market’s small volume compared to sub-6 GHz technology. Cambridge Broadband Networks Group (CBNG) engineers devised innovative solutions to leverage sub-6 GHz components in their FWA radios. EE World engaged in a discussion with CBNG CTO Justin Clark to delve deeper into this topic.
EE World: Senior technical editor Martin Rowe here with Justin Clark from CBNG (Cambridge Broadband Networks Group), specializing in routers for fixed wireless access internet using millimeter waves.
Despite speculation that millimeter wave technology is obsolete, it remains relevant, particularly in FWA applications. Justin sheds light on the challenges of working with limited component volumes compared to cell phones and the ensuing supply chain hurdles. Let’s hear more from Justin.
Clark: Thank you for having me.
EE World: Justin, could you outline some common challenges faced with millimeter wave components?
Clark: Millimeter wave technology presents various technical constraints, primarily stemming from the higher frequencies. These frequencies necessitate intricate design and fabrication of RF components due to smaller geometries on substrates, leading to tighter manufacturing tolerances for optimal performance.
Additional losses in substrates at millimeter wave frequencies demand specialized transmission-line structures like coplanar waveguides and substrate-integrated waveguides. The choice of materials, such as Rogers, Teflon, or ceramics, becomes crucial for mitigating losses and ensuring signal integrity across diverse frequencies and bandwidths.
The complexity of millimeter wave solutions requires a range of substrates and semiconductor components, posing challenges in fabrication, packaging, and thermal management. The bespoke nature of these processes contributes to the high costs associated with millimeter wave technology.
Packaging technologies play a vital role in integrating substrates into packages, with a focus on minimizing losses, managing EMI interference, and enhancing signal coupling. These challenges underscore the need for specialized semiconductor processes and components, further complicating the supply chain dynamics.
EE World: You highlighted the importance of thermal management. How have you addressed thermal issues in small millimeter wave devices?
Clark: Heat dissipation in millimeter wave devices, particularly at the junction of transistors, poses a significant challenge due to low dielectric losses in substrates. Innovative packaging technologies play a critical role in efficient heat transfer from the junction to the PCB, ensuring optimal thermal performance.
Metal substrates with die bonds and flip chip technology facilitate effective heat dissipation, enhancing thermal flow within the device. These advancements in packaging technology enable superior thermal management in millimeter wave devices.
EE World: Given the limited component volumes in the millimeter wave space, how has CBNG improved the supply chain and reduced costs?
Clark: At CBNG, we excel in repurposing components from alternative applications, such as cellular technology, for fixed wireless access. By leveraging components from the sub-6 GHz band for IF frequency, we can capitalize on commercial volumes and minimize costs in millimeter wave solutions.
Our expertise lies in adapting available components to suit millimeter wave applications, ensuring economies of scale while addressing supply chain limitations. By integrating off-the-shelf components with bespoke products, we optimize cost efficiency and enhance the viability of millimeter wave technologies.
EE World: This innovative approach certainly streamlines the integration of RF frequencies. How do you navigate the processing challenges associated with utilizing sub-6 GHz modems in millimeter wave applications?
Clark: Utilizing sub-6 GHz modems in millimeter wave applications presents certain limitations, particularly in bandwidth allocation. By creatively combining multiple modems and optimizing bandwidth utilization, we maximize the benefits of available components while addressing the specific requirements of millimeter wave technology.
Innovative techniques, such as bandwidth stitching and modem duplication, enable us to leverage off-the-shelf components effectively, ensuring seamless integration of sub-6 GHz and millimeter wave technologies.
EE World: Balancing bandwidth requirements and processing power is crucial in optimizing millimeter wave solutions. How do you manage the processing demands associated with utilizing multiple modems?
Clark: The processing power requirements depend on the data rates and bandwidths handled by the system. By leveraging dedicated processors with hardware acceleration functions, we streamline data processing and minimize costs without compromising performance.
Our approach involves doubling up on application processors and partitioning tasks across multiple cores to efficiently manage data rates in millimeter wave applications. This strategy allows us to optimize processing power while leveraging off-the-shelf components for cost-effective solutions.
As the industry shifts towards AI and GPU processing, the availability of specialized processors for niche applications may diminish. However, our focus on utilizing off-the-shelf components with hardware acceleration functions enables us to circumvent these challenges and deliver robust millimeter wave solutions.
EE World: Justin Clark, thank you for sharing your insights on navigating the complexities of millimeter wave technology. We appreciate your time and expertise in this evolving field.
Clark: Thank you, Martin. It’s been a pleasure discussing these critical aspects of millimeter wave technology with you.
Filed Under: AI/ML, Featured, mmWave, Video
