雜談GaN技術

This post was originally published on TI’s TI E2E Community “Power House” Blog. Learn more about eGaN technology here and EPC GaN solutions here.

Televisions can get their content wirelessly, but there is one set of wires they still need: those in their power cord. The consumer electronics industry has floated ideas for freeing TVs from their power cords, but this goal remains elusive. There are several reasons, such as the difficultly of meeting high-power requirements for large-screen TVs and the need for identifying an economical technology. Nevertheless, eGaN FETs could play a role in making TVs truly cordless devices.

The previous installment in this series focused on the physics of failure surrounding thermo-mechanical reliability of EPC eGaN® wafer level chip-scale packages. A fundamental understanding of the potential failure modes under voltage bias is also important. This installment will provide an overview of the physics of failure associated with voltage bias at the gate electrode of gallium nitride (GaN) field effect transistors (FETs). Here we look at the case of taking the gate control voltage to the specified limit and beyond to investigate how eGaN FETs behave over a projected lifetime.

The first three installments in this series covered field reliability experience and stress test qualification of Efficient Power Conversion (EPC) Corporation’s enhancement-mode gallium nitride (eGaN®) field effect transistors (FETs) and integrated circuits (ICs).  Excellent field reliability that was documented is the result of applying stress tests covering the intended operating conditions the devices will experience within applications.  Of equal importance is understanding the underlying physics of how eGaN® devices will fail when stressed beyond intended operating conditions (e.g. datasheet parameters and safe operating area).  This installment will take a deeper dive into the physics of failure centered around thermo-mechanical reliability of eGaN® wafer level chip-scale packages (WLCSP).

Prognosticators do not often risk their reputations by giving their predictions a “checkup” midway through the period of their predictions. But, I am going to give it a shot and here we go…

Every year in January 2017, the world’s consumer electronics community gathers in Las Vegas at the Consumer Electronics Show (CES) to see, learn and discuss the latest innovations and products available in the world of electronics.

More than 3,800 exhibitors spread out across 2.47 million net square feet of exhibit space, is the location where over 170,000 industry professionals, 50,000 outside of the U.S. wander, ogle, and “play with” the latest electronic devices.

In January of 2016 I made several predictions for the then-nascent year. Predictions were made for new markets such as wireless charging, augmented reality, autonomous vehicles, and advances in medical diagnostics and internet access. Progress in these markets was made on all fronts, sometimes faster and sometimes slower than anticipated. So here we are about to start a new year and, perhaps foolishly I am ready once again to predict the future.

Class-D audio amplifiers have traditionally been looked down upon by audiophiles, and in most cases, understandably so. Switching transistors for Class-D amplifiers have never had the right combination of performance parameters to produce an amplifier with sufficient open-loop linearity to satisfy the most critical listeners. This restricted the classical analog modulator Class-D systems to lower-power, lower-quality sound systems.

To accomplish the required headline marketing THD+N performance targets, Class-D amplifiers have had to resort to using large amounts of feedback to compensate for their poor open-loop performance. By definition, large amounts of feedback introduce transient intermodulation distortion (TIM), which introduces a ‘harshness’ that hides the warm subtleties and color of the music that were intended for the listening experience.

In past postings , we looked at the applications that have emerged because of new capabilities available with #GaN technology. We also discussed the transformational nature of some of these applications in areas like medicine, telecommunications,human-machine interfaces, and the delivery of electrical power itself (wireless power transfer). GaN technology is entering an era similar to the 80’s and 90’s when the utility of technological improvement was apparent across broad commercial markets. Consequentially, consumers will be willing to pay a premium for the life-style improvements enabled by these improvements thereby accelerating growth of GaN applications for the foreseeable future.

GaN technology is disruptive, in the best sense of the word, making possible what was once thought to be impossible – eGaN® technology is 10 times faster, significantly smaller, and with higher performance at costs comparable to silicon-based MOSFETs. The inevitability of GaN displacing the aging power MOSFET is becoming clearer with domination of most existing applications and enabling new ones.