Key Takeaways

  • Mobility (freedom of movement, untethered) has become a major desire for the consumer during this century – creating a “Mobility Imperative.”
  • A key performance advantage of eGaN® FETS is speed – these power transistors are about 10 times faster than silicon MOSFETs 1.
  • The speed of eGaN® FETs has opened new applications driven by a Mobility Imperative – envelope tracking, wireless power, and autonomous vehicles – enabling the consumer to be “untethered.”

The Mobility Imperative:
Untethered Consumers!

Consumers want to be able to go wirelessly where they want, when they want. They want televisions to be seamlessly synchronized with tablets, phones, laptops, and automobiles. They want all their communication, information, and entertainment to be available immediately, with high resolution, all the time. Recently the automobile industry has caught on to this trend and has begun to show its vision of the future for the fully mobile lifestyle 2.

Consumers also do not want to worry about running out of battery life – no more looking for an open outlet at the airport. This untethered life is the Mobility Imperative and it is driving innovation in consumer products, which in turn, is pushing the limits of silicon-based semiconductor technology.

As silicon power transistors (MOSFETs) run out of gas, gallium nitride transistors are the next generation semiconductor devices in the world of power conversion and data transmission. Enhancement-mode gallium nitride transistors (eGaN® FETs) from Efficient Power Conversion Corporation (EPC) have been in production for over five years. These devices are smaller in size, superior in performance, and lower in cost when compared with their aging silicon ancestor, the power MOSFET. GaN’s high-speed capability, coupled with lower production costs and smaller size, makes this technology ideal for accomplishing the Mobility Imperative.

Increasing Wireless Bandwidth – Increased Data Transmission, Increased Battery Life

Envelope tracking is a power supply technique for improving the energy efficiency of Radio Frequency Power Amplifiers by precisely tracking the power demand, as compared to today’s fixed-power systems. In cell phones use of envelope tracking means longer talk time, and in base stations it means smaller, less expensive amplifiers that consume far less energy and are less expensive to operate.

Projected Mobile Data Traffic through 2019

Figure 1: Source: Cisco VNI Mobile Data Traffic Forecast 2015 3.

Envelope tracking system

Figure 2: An example of an envelope tracking system using eGaN FETs. eGaN® FETs are the blue rectangles on the circuit board. Photo courtesy of NewEdge Signal Solutions4

As our demand for wireless data grows (see figure 1), the value provided by envelope tracking increases dramatically. More transmitters alone cannot solve the problem; rather, more data transmission bandwidth per power amplifier is required. As the data transmission bandwidth increases, the efficiency of the transmitter’s power amplifier sharply declines unless the system adopts envelope-tracking methods.

Gallium nitride is being seen as an enabling technology for both envelope tracking converters and wide bandwidth RF Power Amplifier designs. The ultra-fast switching capabilities of eGaN FETs enable the high frequency, multi-phase buck converters used in envelope tracking power systems.

Wireless Power Transfer Cuts the Cord…No Need to “find an outlet!”

Since Nikola Tesla first experimented with wireless power during the early years of the 20th century, there has been a quest to “cut the cord” of electrical power – and go wireless! Now, more than 100 years later, the technological capability to achieve Tesla’s vision is a reality.

Highly resonant wireless power transfer, based on the generation of magnetic fields, has proven to be a viable path. Magnetic fields offer the necessary requisites for implementing wireless power – ease of use, robustness and, most importantly, it is considered safe. Applications for wireless power are endless, from charging cell phones and computers, to powering systems in hazardous environments and implantable medical devices.

Wireless power transmission in a home environment

Figure 3: In the future electrical power cords may become obsolete as illustrated in this vision of the home of the future6. Photo courtesy of WiTricity.

With the explosion in the variety and number of mobile devices, wireless power transfer offers the convenience of charging batteries without the annoyance of cumbersome cables and the inconvenience of looking for outlets to “plug in.” Figure 3 is an illustration of what the home of the future might look like with all electrical appliances powered without power cords.

Over the past several years, three standards for wireless power transmission have emerged. These standards, put forth by industry consortia include the Wireless Power Consortium’s Qi, the Power Matters Alliance and the Alliance for Wireless Power (A4WP), also known as Rezence®5. The Rezence® standard is winning because it allows multiple gadgets to simultaneously charge from a single transmitter at a significant distance.

The Rezence® standard for wireless power transmission is already seeing rapid adoption in mobile phone and tablet charging applications. For example, several automotive manufacturers are planning to embed wireless charging systems in the center console of their vehicles so the smartphone, as well as other mobile devices, can remain charged despite intense and continuous usage while the automobile is in operation7,8. Given that the Rezence standard requires a high speed, 6.78 MHz, frequency for power transmission9, eGaN FETs are the heavy favorite for adoption over the slower and less efficient silicon power MOSFET.

Wireless power transmission in a vehicle

Figure 4: Wireless power transfer will be used in automobiles to keep smartphones charged
despite continuous usage as part of the infotainment system7. Photo courtesy of Gill Electronics.

Wireless charging for electric vehicles is also becoming more available10 as electrically powered cars become more prolific. Although there is no universal standard yet, loosely coupled magnetic energy transfer, similar to the method used in the Rezence® standard, is common to all implementations. This is due to its ability to transfer power without precise alignment of transmitter and receiver units. eGaN® FETs are certainly a good candidate technology for this application.

Be on the lookout for Automotive Sensing and Autonomous Control — Collision Avoidance or “Relax and Enjoy the Ride” — in a future Fast just got Faster

For safety reasons, it is critical that a car know what is around it at all times. This becomes even more essential as the car evolves into a self-driving machine. Further, the higher the speed of the vehicle and the more complex the surroundings, the faster the environmental sensing system needs to be, and the more precisely it needs to interpret the distance to a potential collision.

Today automotive manufacturers use a variety of sensors in these functions, including Light Distancing and Ranging (LiDAR) sensors that have only recently begun to emerge in automotive sensing autonomous driving applications. Automotive applications using gallium nitride technology will be presented in an upcoming Fast Just Got Faster article.

Summary

In conclusion, a “Mobility Imperative” is upon us…the modern consumer is demanding that:

  • they do not want the range anxiety caused by the worry about running out of battery life and having to “find an outlet.”
  • all their information and entertainment be available all the time via their smartphone …all in high resolution and all “right now.”

Gallium nitride is the fundamental technology bringing the “Mobility Imperative” to reality since it provides:

  • increased switching speed leading to higher resolution and less power consumption.
  • smaller size, thus enabling product miniaturization and weight reduction.
  • low product costs, thus stretching the consumer dollar farther.

Consumers want to be able to go “mobile” wherever and whenever they want…this is today’s Mobility Imperative and it is driving innovation throughout consumer electronics.

The current semiconductor technology, silicon power transistors (MOSFETs), has reached its performance limits; fortunately, gallium nitride transistors with its high-speed capability coupled with lower production costs and smaller size, has come of age. It is GaN technology that will make Tesla’s vision come to fruition…and make it possible for us to achieve the Mobility Imperative.

  1. A. Lidow, J. Strydom, M. de Rooij, D. Reusch, GaN Transistors for Efficient Power Conversion, 2nd Edition, West Sussex, England: John Wiley and Sons, 2015.
  2. J. Siu, “Car Buyers Love Wireless Connectivity: Study,” Autoguide.com, May 4, 2014.
  3. http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networking-index-vni/white_paper_c11-520862.html
  4. D. McIntosh, “WSC: Innovative Use of enhanced mode GaN power FETS in medium power Envelope Tracking Modulators,” IEEE International Microwave Symposium, Tampa Bay, FL., June 2014.
  5. R. Tseng, B. von Novak, S. Shevde and K. A. Grajski, “Introduction to the Alliance for Wireless Power Loosely-Coupled Wireless Power Transfer System Specification Version 1.0,” IEEE Wireless Power Transfer Conference 2013, Technologies,Systems and Applications, May 15–16, 2013.
  6. D. Schilling, “WiTricity Charges Forward with Wireless Electricity,” Industry Tap Into News, January 10, 2013.
  7. J. Day, “Gill Electronics signs wireless agreement with Qualcomm,” John Day’s Automotive Electronics, June 24, 2013.
  8. J. Day, “Delphi developing in-vehicle cordless charging,” John Day’s Automotive Electronics, May 1, 2012.
  9. M. de Rooij, Wireless Power Handbook: A Supplement to GaN Transistors for Efficient Power Conversion, El Segundo, CA: Power Conversion Publications, 2015. (Publication date: March 2015)
  10. N. Gordon-Bloomfield, “Hertz Tests Wireless Charging For Electric-Car Rentals,” Green Car Reports, February 9, 2012.