Cloud Data Center Evolution - From 0 to 400G   Nov. 07, 2017

Data Center Evolution.jpg (583997004)Cloud services and consumer products that rely on Cloud Data Centers have created a rapid evolution in Data Center capabilities. As services like the Internet of Things (IoT), audio/video content delivery, big data processing and social media continue to demand greater speeds, the Cloud Data Center industry is making strides to create solutions that are energy efficient and easily expandable. As a result, the need for low cost 100G is creating a shift in how the industry approaches the backbone hardware that enables Cloud Data Centers to respond and expand for both commercial and consumer needs. As Cloud Data Center providers work to find energy efficient low-cost solutions, the industry is looking toward future requirements that meet these needs as well. The evolution from 0 to 100G is just the beginning.

The Need for Low Cost 100G

The above stated increased traffic within and between Cloud Data Centers is driving the need for low cost 100G, moving to high-speed and low power 200G and 400G interconnects. Starting in 2018, Cloud Data Center OEMs will adopt new technology, allowing them to increase bandwidth density per port. Smaller QSFP, QSFP-DD and OSFP form factor modules will support these interconnects. The shift requires suppliers to deliver lower power electronic components that are reliable over time. One solution is to drive chipset innovations that address the power and bandwidth density needs by supporting single wavelength interconnects. When combined with silicon photonics, this approach fulfills the power envelope requirements of these smaller form factor modules.

New Capacity Requirements

Looking back, transceiver technology was expensive and power hungry. Silicon technology advances over time allowed for more affordable hardware and energy-efficient operations. But the limits to the capabilities of the current transceiver architecture are already here and today's Cloud Data Centers are at maximum capacity.

On average, large scale Cloud Data Centers need to upgrade networking hardware every two years. With the switches that are currently in use, the cost of the optical transceivers is a major contributor to the upgrade cost. Next generation 100G solutions using PAM-4 technology can help address these issues and lower the cost per bit in the future.

This new approach to 100G has benefits in the near and long-term. It increases density, lowers power and lowers cost per transmitted bit, thereby significantly improving overall efficiency. As companies continue to grow in scale and their data needs become more complex, 100G per lambda will be a building block to next generation 400G, which offers the bandwidth and efficiency they desperately need.

100G PAM-4: The best solution for 100G

Understanding the current market challenges and the growing need for speed shows that PAM-4 is the best approach for a scalable solution. 53Gbaud PAM-4 modulation using mixed signal PHYs can address the challenge from the industry and provide lower cost hardware and more energy efficient solutions over time. For 100G transceivers, single-wavelength PAM-4 technology reduces the number of lasers to one and eliminates the need for optical multiplexing. The 2 bits / symbol approach of PAM-4 reduces the bandwidth requirements, while improving cost and power per bit. Digital Signal Processing (DSP) provides flexible and adaptable equalization, allowing 100G transmission over single mode fiber up to the distance of 2 Km.

PAM-4 proves to be the most cost-effective, efficient enabler of 100G and 400G in the Cloud Data Center to date. For 400G implementations, only four optical assemblies are needed, representing a major opportunity for Cloud Data Center operators to reduce their CAPEX and OPEX with an extremely compact and energy efficient module.

The Best Solution

Research and testing shows that single lambda PAM-4 supports the increased speed requirements of Cloud Data Centers and is achievable with technology that exists today. PAM-4 and the shift in approach to 100G provides a 60% reduction in component count along with a 33% reduction in power requirements. The significant reduction in assembly costs and higher reliability deliver initial and long-term value and provide the infrastructure required to reach 400G as well. At 400G, this technology is adaptable and can enable QSFP-DD or OSFP form factor transceivers. The PAM-4 approach delivers the best overall solution for speed and affordability in Cloud Data Centers.

Optical and Electrical Results

With its streamlined architecture, lower cost and higher reliability, single lambda 100GE PAM-4 or 100G Serial, can be seen as the equivalent of SFI at 10GE. SFI and SFP+ enable the cost reduction and high density required to drive the growth of 10GE.

The single lambda 100G solution offers the optimal component count with the simplest architecture. This brings the potential to achieve the lowest cost as a result. In addition, reducing the optical components to the minimum required set enhances module reliability, manufacturing yields and reduces the chance of optical component failure. 100G per lambda is poised to create the next wave of explosive growth in mega Cloud Data Centers. 

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Designing with Diodes: Why Choose AlGaAs?   Oct. 24, 2017

Picture1.pngFor decades, solid state control components such as PIN diodes have been used in RF and microwave control devices, such as switches and attenuators. PIN diodes act as charge-controlled variable RF resistors, producing low insertion loss, large isolation, excellent power handling and excellent linearity, and in many cases better than any field effect transistor can produce. The range of impedance that a PIN diode can present can be as large as 5 or 6 decades, the extremes of which approximate an open and a short circuit.

PIN diodes can be placed either in series or in shunt with transmission lines, such as microstrip, coplanar waveguide and more. The resistance and capacitance of the PIN diode determine the insertion loss and isolation, respectively, for a series connection, or the converse for a shunt connection.




The PIN diode is a 3-laye rdevice, composed of

  • the anode, an acceptor-doped (p-type) P layer
  • an undoped (intrinsic) I layer
  • the cathode, a donor-doped (n-type) N layer

When this structure is approximated as a right-cylindrical section, we can see that the area of the junction and the thickness of the I layer determine the capacitance (C) of the PIN diode when it is not conducting and the series resistance (R) of the diode when it is biased into conduction according to the elementary equations:



The permittivity of the I layer (e) and its resistivity (r) are determined by the type of material comprising the diode.The thickness, also known as the length (l) of the I layer, determines or affects several performance parameters, including among other parameters the capacitance of the diode, the resistance of the diode, the diode’s avalanche breakdown voltage and the produced harmonic distortion.The area of the diode junction primarily affects C and R.

The practice of electronics design is inviolably an exercise in making trade-offs. As the frequencies at which PIN diodes are used have increased, the required capacitance of the diodes must be smaller in order to achieve acceptable performance. This has primarily been achieved by reducing the area of the junction.  This reduction in capacitance came at the price of a commensurate increase in series resistance, which resulted in increased insertion loss for a series-connected application or decreased isolation for a shunt-connected application. Short of increasing the I layer thickness, which also produces increased series resistance, there was nothing else the design engineer could do.

Series resistance can also be defined in terms of the semiconductor physics properties of the diode.



Where l is the thickness of the I layer, µamb is the ambipolar mobility of the charge carriers injected into the I layer and Q represents the amount of free charge carriers injected into the I layer.

As frequencies increased to the point that the µamb of Si produced series resistance which was too large, materials with greater value µamb, such as gallium arsenide (GaAs) were adopted. For millimeterwave (mmW) applications, even the higher value of µamb of GaAs has shortcomings.

To solve this need for better resistance and lower capacitance at millimeterwave frequencies, MACOM has developed heterojunction PIN diodes using a novel aluminum gallium arsenide (AlGaAs) structure to address the limitations of GaAs and Si PIN diodes. The AlGaAs PIN diodes are also three-layer diodes, but with a significant difference: aluminum (Al) is used as a p-type dopant in the anode layer of the diode. The I and N layers of the diode comprise GaAs. The addition of Al to the anode layer increases the band gap of the diode junction with respect to that of a GaAs PIN structure.This difference produces a greater barrier to diffusion of holes from the I layer back into the P layer when the diode is under forward bias, thus increasing Q, the amount of free charge carriers in the I layer. This increase in the forward-bias charge carrier population in the I layer reduces the series resistance of the AlGaAs PIN diode, without changing the diode’s reverse bias performance. 

The net effect is that one formerly inviolable trade-off has been eased: for an AlGaAs PIN diode and a GaAs PIN diode with identical I layer lengths and identical resistance values, the AlGaAs PIN diode can have a smaller junction area with lower junction capacitance, enabling improved circuit performance.

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Solid-State Plasma Lighting: The Benefits and Target Apps for LEPs   Oct. 10, 2017

Plasmablog.jpgPlasma lighting – also commonly referred to as light emitting plasma (LEP) – is quickly evolving into a mainstream technology, and is on a trajectory to supplant LEDs and high intensity discharge (HID) lighting across a host of applications where plasma lighting outperforms legacy light sources. The first step in this evolution toward commercial-scale adoption was to overcome the reliability and lifespan limitations of earlier-generation magnetron-powered plasma lights. This was made possible via innovations in solid-state plasma lights, powered by RF Energy, and underpinned by GaN semiconductor technology. Check out our earlier blog post on this topic to read more: RF Energy in Daily Life: Plasma Lighting.

The next step in this evolution was to help enable commercial OEMs to adapt their product designs to incorporate GaN-on-Si-based RF Energy, making it easier for them to take advantage of this unfamiliar technology. Leveraging an RF Energy Toolkit, lighting system designers are now well equipped to reduce development complexities and costs, and accelerate their time to market with solid-state plasma lighting – it will not be long before we see this technology in commercial production. In this blog post we will take a look at some of LEPs’ key benefits, and the mainstream applications where solid-state plasma lighting is primed for adoption.


One of plasma lighting’s major advantages over legacy light sources is its ability to emit a lot of light from a very small space. LEPs are characterized by extremely high lumen density – an LEP bulb the size of your fingertip can produce 10,000 lumens of light. In contrast, a similarly-sized, high-density LED light would need an array of LED in something like a 100cm x 100cm panel.

LEPs are therefore well suited for implementation in vehicle headlights, as they can provide considerably brighter illumination than LEDs, HIDs and halogen lights in a given form factor. This ensures better road visibility and improved driver/passenger safety – benefits that we anticipate will be replicated in other transportation modes, including trains, marine vessels and beyond.

LEPs are also ideal for science and medical applications where bright, high-quality light is essential, but there is limited space available to deploy it in. The use cases here could include everything from operating rooms and medical labs, to endoscopy devices and microscopes. 


The high lumen density of LEPs also makes them an ideal candidate for replacing LEDs and high pressure sodium (HPS) lights for wide area lighting in environments like parking lots, warehouses, stadiums, airports and shipping ports. The high level of visual acuity and enhanced color rendering enabled by LEPs also gives them an edge in outdoor showrooms like car dealerships where consumers are drawn to brighter, crisper viewing experiences.

In all of these wide area lighting use cases, the high levels of visual acuity and the even light distribution delivered with plasma lights ensure that everyone in the vicinity has greater awareness of their surroundings. This can improve safety among workers and pedestrians alike, while helping to enable to higher-quality workplaces (and play spaces!).


One application where plasma lighting has already made considerable inroads is horticulture. Grow lighting environments, both big and small, are benefitting from LEPs’ unique ability to emit a continuous, full-spectrum light akin to natural sunlight – including ultraviolet UVA and UVB – without the need for a secondary phosphor conversion such as those used by LEDs.

Plasma grow lights also enable the unique capability to tune the lighting to different frequencies and light spectrums. Plant growth can be enhanced in many ways depending on the type of light emitted on specific parts of the plant, so spectrum tunability can be invaluable for growing healthier plants, fruits, vegetables etc., and can also help increase the potency of plant-based medicines.


Designers of next-generation lighting systems are of course also mindful of power efficiency and associated OPEX considerations, as well as reliability issues that could lead to higher maintenance costs. After all, producing brighter, higher-quality, full spectrum light is only beneficial to the extent that it can be cost-effectively implemented. 

With LEPs, the source efficacy – or lumens created per watt consumed – is up to 20% higher than HID sources, and will be comparable to LED source efficacy. Since LEP bulbs do not utilize electrodes – which degrade over time and represent a common point of failure for many legacy light sources – they are considerably more reliable, and have demonstrated 50,000 hour lifespans.


The benefits of solid-state plasma lighting are manifold, making LEPs an attractive option for a wide range of applications going forward. In a subsequent blog post, we’ll do a deeper dive on the many benefits of LEPs relative to LEDs, addressing some of the common points of comparison between these two trendy technologies. We’ll also take a closer look at how GaN-on-Si technology impacts the respective design considerations for LEP and LED light fixtures. In the meantime, there is plenty of additional background information available on RF Energy technology and target applications if you’re interested in learning more. 

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RF Energy in Daily Life Part 4: GaN for Industrial Heating and Drying   Sep. 12, 2017

BlogRFEIndustrial.jpgGallium Nitride (GaN) and RF (Radio Frequency) Energy applications are on the cusp of transforming the industrial market. We have examined how GaN has changed cooking, plasma lighting and medical processes, and in part four of our RF Energy in Daily Life series, we are going to look at GaN for industrial heating and drying.

From an industrial standpoint, RF Energy is not new. RF dryers have been used for industrial heating and drying of materials that don’t respond well to traditional methods for years. Ceramics, glass and fiberglass applications require processes that dry without cracking. Where other methods failed entirely, in many cases, RF Energy provides the only option for drying these materials, as it can eliminate moisture in a controlled way.

Innovations in RF technology will allow for greater efficiencies and control throughout the heating and drying process going forward. Yesterday’s RF applications required the use of a magnetron to generate energy, but by using semiconductor devices, the total system cost structure is lowered and the applications have greater precision and control. The resulting uses for food processing, industrial heating and drying, and the energy industry are just the beginning. The low costs and high precision involved are allowing industry leaders like MACOM to deploy innovations throughout the marketplace.

Agricultural Processes and RF Energy

In previous blog posts, we have discussed how consumer cooking capabilities will be revolutionized by RF technology. However, the applications for food processing begin much earlier in the supply chain, with the role of RF in assisting the pasteurizing and drying processes. As the National Institutes for Health (NIH) points out, drying is an indispensable process in many food industries and in many agricultural countries. Their research states, “Large quantities of food products are dried to improve shelf life, reduce packaging cost, lower shipping weights, enhance appearance, encapsulate original flavor and maintain nutritional value.”

The higher precision and control of RF Energy for commercial drying processes provides considerable benefits to numerous other agricultural applications. For example, farmers and industrial food producers battle harvesting crops against the wreckage caused by longer drying times. For grains, legumes and seeds, RF drying methods eliminate moisture faster and reduce processing times, allowing crops to be used for maximum potential and nutritional benefit. Not only can RF Energy cook the food in your home more efficiently, it will also become part of the agricultural processes to get quality nutrition to your door. MACOM and the RF Energy Alliance are leading the way in enabling solid-state technology for these applications, removing price and size barriers from the process.

Paper, Textiles and Wood   

In their book Radio-Frequency Heating in Food Processing: Principles and Applications, George B. Awuah, Hosahalli S. Ramaswamy and Juming Tang detail applications from dried vegetables to alfalfa that are enabled by RF heating and drying methods. They also note that wood, plastics, pharmaceuticals, papers and textiles all can use RF Energy for lower costs and increased efficiencies to the industrial process. As RF energy changes the basic steps in manufacturing for each of these materials, the applications are expected to expand as well. Leaders like MACOM are changing the basics of industry by combining GaN and solid-state semiconductor technology with these processes for widespread use with lower costs.

Oil Extraction  

RF Energy uses less energy than traditional drying and heating methods, and the level of precision allows every watt to be used efficiently. From a conservation standpoint, this benefits the industry in two ways – less cost and greater control.

But another energy benefit beyond consumption is the industrial drying and heating applications of GaN and RF as they apply to the oil industry. Companies like Suncor are already experimenting with RF Energy to add heat to the oil extraction process and produce heavy crude. Chevron has filed patent claims on the use of RF in multi-step processes as a method of extraction as well. These techniques will allow oil companies more access to oil with greater control over their extraction. Less waste, higher return on deposits, and a lower cost for heating and extraction processes stand ready to change the oil industry.

Reduced Environmental Impact

Employing solid state technology is expected to change the environmental impact of oil extraction as well. Fracking is an oil extraction technique that involves using heated water and chemicals to produce crude oil. The side effects of the process include polluted water and even manmade earthquakes. RF Energy allows for a cost effective alternative that reduces the water used and the resultant polluted debris. In addition, the precision of these oil extraction methods leads to less overall environmental impact. Higher levels of control allow RF Energy to improve extraction methods while also reducing Greenhouse gas emissions.

Improved Reliability

Another benefit of solid state RF Energy devices in these industrial applications that shouldn’t be forgotten is the improved reliability it brings to processes that often run 24/7. While magnetron based systems typically degrade over time and need constant maintenance or replacement, the new solid state based systems are capable of running free of maintenance, without experiencing any degradation.

Industry and Beyond

As the opportunities for RF energy to enable improved processes with more control continue to grow, MACOM continues to work with industry leaders to apply best practices and enable RF Energy with our GaN-on-Silicon (GaN-on-Si) solutions. Be sure to learn more about the trending applications for RF Energy and how they apply to you in daily life, and check out MACOM’s toolkit, created to ease the process of designing with RF Energy applications.  

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