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Why Choose RF Energy for Automotive Ignition?   May. 09, 2018

automotive ignition.jpgPerhaps one of the most lucrative commercial applications available to solid-state radiofrequency (RF) energy is in the automotive industry, known for its dedication advancing vehicle technology with every model. Traditionally enabled by spark plugs, vehicles can now benefit from RF solid-state plasma technology, which offers improved fuel efficiency and reduced carbon footprint.

What is RF Energy?

The concept for RF energy powered ignitions dates back to 1992, following the 27th Intersociety Energy Conversion Engineering Conference in San Diego, California, where the idea of lean, precise automotive ignition without the use of the traditional spark plug was first introduced. Automakers grappling with increasingly stringent vehicle emissions protocol, allowing for only a small carbon footprint and facing potential fines for every car which omits over protocol, were in need of a seamless solution to improve efficiency without completely redesigning the engine. Solid-state RF energy presented an opportunity to offer an unprecedented level of control and efficiency to auto ignitions, thereby reducing waste and cost, with equivalent footprint. At the time, further analysis was required in order to control the physical volume of plasma created by the RF discharge.

Today, due to recent advancements enabled by organizations like the RF Energy Alliance, innovative new technologies such as MACOM’s GaN-on-Si displacing incumbent LDMOS and collaborations like STMicroelectronics and MACOM, RF energy is now poised to achieve the optimal performance, scale and cost structure to enable this formerly “futuristic” application. Fuel efficiency improvement has become a choice not only for car manufacturers, but for consumers to demand as standard.

Spark Plugs vs. RF Plasma Ignition

The concept of spark plugs are simple: deliver an electric current to a vehicle’s combustion chamber, emit a one-time electric spark—similar to that of a lightning bolt—to ignite the compressed fuel and air mixture, which then moves the pistons of the engine and voila. Due to the erratic, natural behavior of the initial spark, the technology is inconsistent in terms of duration per start and amount of gas expended per start. Generating a high voltage spark in combination with the timing it takes to start the “cranking” of an engine, any gasoline which lies in the ignition chamber is burned, even if gas levels are low or diluted. Though fractional in seconds, the use of unnecessary gas combinations accumulates. Despite these inefficiencies, many car manufacturers have stuck with spark plugs due to the familiar technology and low cost structure (previously unavailable with an RF plasma solution).

RF plasma, on the other hand, offers a constant array of energy. The constant energy source is beneficial to a vehicle, bringing higher combustion ratios, the ability to control and manipulate the plasma, and operate flawlessly under extreme pressure time and time again—whereas traditional spark plugs can only work to a certain pressure constraint, resulting in fuel mixtures which are sub-optimal.

By leveraging RF energy in lieu of a spark plug, fuel in the combustion chamber can be ignited much more evenly than with conventional ignition systems. The precision control afforded by RF plasma-powered ignitions can largely reduce exhaust emissions and save on fuel by using a plasma to accurately optimize the fuel combustion process. Aggregated globally, a 10% improvement in fuel efficiency for combustion-powered vehicles would represent a significant leap forward in carbon emissions control. 

Looking Forward

RF plasma ignitions not only have the potential to better serve the automotive industry, but can optimize performance in motor bikes, diesel trucks, large industrial engines and more. MACOM has recently started to develop an integrated circuit, the Analog Lock Loop, which is expected to provide a cost effective control loop for the solid state amplifier to deliver energy efficiently to the RF plasma ignition under the controlled environment. Following MACOM’s recently announced collaboration with STMicroelectronics to commercialize GaN-on-Si for RF markets, a plasma ignition could be in a low-end car market sooner than you think!


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5G Wireless Fronthaul: Achieving the Benefits of C-RAN and CPRI with 100G Optical Connectivity   Apr. 24, 2018

5g wireless fronthaul.jpg (544581870)In a previous blog post we assessed the evolution of 5G wireless standards and industry expectations for the incremental deployment of 5G infrastructure in the years ahead. Continued forward progress on these fronts brings us ever closer toward a future of breakthrough bandwidth capacity and data delivery speeds. There will of course be daunting technology challenges on the pathway to 5G, but these challenges present tremendous opportunities for wireless operators to evolve our wireless infrastructure in a scalable and sustainable manner that enables continuous improvements in bandwidth, power, management and cost efficiencies.

Wireless fronthaul is a prime example of this dynamic, inviting a fresh look at the underlying network architecture extending from remote radio units (RRUs) to baseband units (BBUs). Taking a comprehensive view of wireless fronthaul trends and standards, we see a clear opportunity to combine parallel advancements in RF and optical technologies to realize a more elegant and cost effective fronthaul architecture that’s optimized to accommodate the huge increase in 5G data throughput.

CENTRALIZED NETWORK ARCHITECTURE

At the RF antenna layer, advanced phased array technologies are enabling massive MIMO configurations that multiply the capacity of antenna links leveraging anywhere from 16 to hundreds of densely clustered antennas. Meanwhile, each individual antenna is targeted to serve more and more bandwidth, from 60 MHz today to as high as 200 MHz for the 3.5 GHz frequency band, and far higher – as high as 800 MHz – for mmWave frequencies.

The data throughput enabled by this advanced RF architecture is immense, but introduces significant dilemmas about how best to partition the attendant signal processing burden between the RRU and BBU to maximize overall data throughput. If the baseband processing is integrated into the RRU via an “All-in-One BTS” approach, then RRU power consumption will rise dramatically, as will maintenance and upgrade costs. This approach runs counter to the inherent benefits of the Centralized/Cloud Radio Access Network (C-RAN) architecture, whereby the RRU design is greatly simplified and the processing intelligence instead resides at a centrally managed, maintained, and cooled BBU servicing a multitude of RRUs over long distances.

C-RAN leverages the natural efficiencies of virtualized, general purpose server infrastructure, with highly flexible, software defined programmability. With C-RAN, it’s also much easier to administer and implement algorithms to mitigate inter-cell interference and improve spectral efficiency.

CPRI vs eCPRI

Though C-RAN promises many benefits for 5G wireless fronthaul, it’s not without its challenges. Chief among them, the long distance functional split between BBU processing and RU requires an ultra high speed optical interconnect to minimize latency. The Common Public Radio Interface (CPRI) protocol, established in 2003, is commonly employed for this purpose today over distances of tens of kilometers, but has been bandwidth constrained in the absence of low cost, high speed optical connectivity solutions.

Published in 2017, the CPRI Over Ethernet (eCPRI) specification aims to address this issue in part by moving a portion of the processing workload from the BBU over to the RU, where the dataflow can be pre-processed in a manner tailored for the requirements of specific 5G uses cases including fixed wireless, massive broadband, and ultra low latency applications. But here again, this approach runs counter to the core value proposition of C-RAN and the centralization of processing workloads and network administration at the BBU.

5G network split options under consideration (image courtesy of eCPRI Overview/IEEE)

5G network split.png

As an alternative approach to eCPRI, data compression techniques are now being developed for implementation at the RRU, targeted to accommodate the extreme data throughput introduced with massive MIMO while ultimately reducing fronthaul bandwidth requirements to a level commensurate with today’s LTE MIMO architectures – a CPRI data rate that’s serviceable with 100G optical interconnects. By compressing the dataflow from the RRU to the BBU, the combined benefits of CPRI and C-RAN can be readily achieved, enabling BBU-level consolidation of baseband processing and management operations.

MACOM’s innovative 100G single-wavelength PAM4 DSP and advanced silicon photonics technology deliver a high-performance, cost-effective 100G optical solution for C-RAN networks. Where previously the CPRI protocol enabled streamlined C-RAN architectures but fell short in data delivery speeds, the mainstreaming of 100G optical connectivity has bridged this gap, thanks also to the volume scale deployment of 100G connectivity in cloud datacenters, and the resulting reduction in 100G cost structures. Wireless operators are now well positioned to exploit the speed and cost efficiencies of 100G interconnects for wireless fronthaul in preparation for the 5G data deluge, while enabling a flexible C-RAN architecture designed for seamless scalability into the future.

MACOM’s leadership across the RF and optical networking domains gives us unique visibility into the technologies, trends and standards driving the development and deployment of 5G connectivity. To learn more about MACOM’s 5G solution portfolio, visit https://www.macom.com/applications/wireless-networking-and-communic/5g


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Multifunctional MMICs: Integrating Size, Weight, Power and Cost for Next Generation Applications   Apr. 11, 2018

In today’s competitive marketplace, almost every new project becomes an engineering feat. System designers continue to demand more functionality in a smaller package, all while serving the same, or lower cost. The multifunctional Monolithic Microwave Integrated Circuit (MMIC) was designed in an effort to provide customers with an affordable, highly integrated unit delivering the same reliability and performance from previous single-function MMICs. Engineers are expediting the evolution of MMICs in order to bolster functionality into highly integrated parts which free up space for system designers’ printed circuit boards (PCBs). This trend will not dispel anytime soon; customers will continue to demand optimal size, weight and power (SWaP), leaving the challenge to system engineers and design teams to find that perfect solution.

What is Driving this Change?

This demand does not make single-function MMICs obsolete; they still serve multiple applications across the board and are great for proof of concept. However, many of today’s applications, such as radar and commercial 5G, face size constraints; the pitch for antenna elements in a phased array at 28 GHz, for example, is only 5 mm, which leaves no space for multiple integrated circuits (ICs). The need for higher frequency necessitates multifunction integration as real estate on the PCB becomes scarce.

Picture four single-function MMICs on a PCB, versus one multifunctional one. Using single function ICs, solution size is fundamentally limited due to overhead of packaging and external decoupling; within a package, the active device takes only a small percentage of space, with the rest being overhead to connect into and out of the package. Today’s technology needs to be continuously advancing its size and performance with each generation. A multifunctional MMIC presents the opportunity to free up extra space on the PCB, making it smaller and easier to fit into different packages to fulfill the application of the customer. This allows for more variation in a smaller package, ultimately providing more development opportunities for the customer.

Multifunctional MMICs will look the same as previous generation single-function MMICs; this single “chip” will serve the same purpose for the customer as previous generations MMICs have, with the difference lying in the amount of functions each “chip” is able to serve (See Figure 1). Increased space is the product of more precise functionality.

Figure 1:

MAOCM MMICs.png

macom mmics 2.PNG

Integration reduces parasitic losses on PCBs. In turn, this reduces the need for excess gain, driving down the total system power consumption. Cost is reduced in the die packaging and by reducing the number of interfaces, the mechanical and thermal reliability—which in many cases drive the total ownership costs—are greatly improved. If the customer requires various functions or more real estate on their board, the new generation of MMICs is ideal.

Driving Total Ownership Cost ↓

Across the industry, companies are migrating to multifunctional MMICs, and customers will need to choose their suppliers carefully. The new levels of integration will drive down customer cost; however, differentiated processes will be required to discern functionality and performance.

Following the trend common to all semiconductor markets, integration brings scale, and scale brings cost reductions. Non-semiconductor costs such as assembly and test are often more labor intensive and time consuming, and thus scale linearly with the number of discrete components produced. Reducing the number of interfaces reduces the number of assembly steps, and also reduces the number of failure points, thus improving yield and reducing the test vectors required. And with the interfaces now internal to the multifunction MMIC, the burden of test on the customer is further condensed. Packaging is also more cost effective; including four functions in a single package is almost four times less costly than to divide into four separate packages. In turn, the simplified packaging allows for better thermal characteristics, which reduces the heatsink requirements, resulting in less overall weight.

Depending upon the key performance targets, differentiated processes may be required to achieve optimal functionalities within the multifunction MMIC. Consequently, semiconductor companies with a rich and diverse technology portfolio are justifiably best positioned to offer the most compelling solutions to system designers. Systems designers will benefit from the vendors who can offer mature and qualified variants to achieve the desired performance.

Looking Forward

Further benefits can be extracted for system designers when the system solution is designed in a partnership. Whether leveraging MACOM’s vertical integration capabilities, or our extensive applications support and system expertise, customers will find MACOM provides the necessary one-stop shop for all their needs. We enable OEMS to take full advantage of the real estate on the board and boost performance and functionality while keeping down overall costs.

The evolution of multi-functional MMICs will continue as engineers continue to innovate optimal solutions to meet customer needs. Integration is key to enabling next-generation applications, regardless if it is RF or optical. From MACOM, one can expect an even higher level of integration of RF and microwave chipsets. In the data center and optical transport world, integrated products will provide data conversion and data transport solutions coupled with RF and microwave solutions to provide a very high level of integration that will ultimately drive optimal affordability and reliability. To learn more about MACOM's MMIC solutions, visit: www.macom.com/mmics


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RF Energy in Daily Life Part 5: GaN for Baking   Mar. 27, 2018

RF Energy Baking Blog.jpg (465605346)The inherent limitations of magnetrons as a heat and energy source have boosted innovation in controllable high-power RF techniques, while simultaneously in the semiconductor world, the performance limitations of LDMOS have fueled solutions like MACOM’s GaN on Silicon (GaN-on-Si) technology. This parallel evolution of Solid-State RF Energy (SSRFE) and RF GaN-on-Si has opened wide the door of opportunity to transform the marketplace via improved performance for commercial applications, including lighting, medical, automotive, cooking and for the purpose of this post—baking.

Why GaN-on-Si for Baking?

GaN-on-Si devices are targeted to underpin solid-state RF energy systems, offering an ideal balance of performance, power efficiency, small size and reliability, at an increasingly attractive cost structure at scaled volume production levels. The performance benefits are evident—GaN-on-Si can deliver exceptional power and frequency capability in addition to higher scalable raw power density and higher efficiency than afforded by LDMOS. With GaN-on-Si’s scalability to 8-inch substrates, it is expected to yield RF devices that are more cost effective at scaled volume production levels than LDMOS in dollars per watt. For system designers and commercial OEMs weighing up total system bill of materials and performance for solid-state RF energy applications, GaN-on-Si is a viable and increasingly attractive solution.

Why SSRFE for Baking?

Today’s magnetron-based microwave ovens are unable to adapt to the energy being reflected from the food into the cavity, instead often relying on a rotating turntable at the base of the cavity to aid the heat distribution. This imprecise delivery of energy often results in overcooking and hot spots that can lower a food’s nutritional value, and cold spots that can negatively impact a meal or dining experience.

But through the use of multiple solid-state power amplifiers and antennas with closed-loop control between the RF amplifier and RF synthesizer to adjust for energy absorption and radiation, energy can now be directed with great precision to its target, ensuring optimal temperature control.

Instead of relying on moisture sensors to measure humidity in the cavity, solid-state microwave ovens measure the properties of the food as it cooks or bakes, and adapt accordingly to changing load conditions or the current condition of the food. This results in increased retention of the nutrients, moisture and flavors of the food.

Consumers will benefit from SSRFE in significant ways centric to system reliability, food processing speed and throughput. The evolution of the solid-state microwave oven is expected to result in a device that is capable of cost-effective baking with unprecedented efficiency, ensuring a cake rises and bakes evenly, and cupcakes on the outer rim of the pan bake as evenly as those in the center. Additionally, the preciseness of the controllable solid-state energy offers opportunities to save energy, money and time in the kitchen, offering the benefit of consistency over the life of the appliance.

Looking Forward

As RF energy applications continue to emerge, MACOM remains committed to driving RF GaN-on-Si solutions to enable SSRFE in commercial applications at cost-effective production levels. RF energy for baking is a concept still in its infancy, but as solid-state microwave ovens begin to emerge on the market and continue to demo successfully, such as MACOM’s demonstration at EDICON 2017, the potential and promised benefits are something the industry can get excited about.


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