Moore's Law's Revival

Silicon is Running Out of Gas

In the last issue of Fast Just Got Faster, we discussed the fact that the investment returns from semiconductor companies have underperformed the S&P 500 since the turn of the century. One of the key reasons for this underperformance is the increased investment required for each new generation of silicon-based product. This is a reversal of Moore’s Law that describes the ever-shrinking transistor and the correlated cost reductions that could be passed on to the consumer.

In figure 1, this phenomenon is shown in the form of a graph indicating the number of transistors that can be purchased for $1 as a function of time. For the first time, in 2012 the curve turned downward as the cost per transistor started to climb due to the required investment for each new generation outpacing the resulting cost reduction. The implications are far-reaching, as it was the consistent drop in cost year-after-year that fueled the vitality of the $300B semiconductor industry for the past six decades.

eGaN Technology Resurrects Moore’s Law

The highest selling product in the world of power electronics is the silicon power MOSFET. In Issue 3 of Fast Just Got Faster, we described the metrics that predict the displacement of the aging, but still dominant, power MOSFET with transistors made from gallium nitride (GaN). In subsequent editions, we discussed the amazing new applications that didn’t exist until GaN’s superior performance became widely available in 2010. Wireless power transmission, RF envelope tracking, LiDAR for autonomous vehicle and new medical devices all rely on GaN’s high speed and small size. Together, these new markets almost equal the size of the existing markets. The innovation enabled by eGaN technology is creating new market opportunities almost every week!

EPC is launching a new generation of eGaN FETs in June of 2014. True to Moore’s Law, these fourth-generation transistors incorporate many technology breakthroughs that double the performance compared to the prior generation (Generation 2) while continuing to reduce cost. This doubling of performance is embodied in two of the basic attributes of a power transistor – on-resistance and switching speed. The lower the on-resistance, the less power is lost inside the transistor when it is operating. The faster the switching speed, the more you can miniaturize your system. Figure 2 is a comparison between the on-resistance of Generation 2 and Generation 4 products, with device ratings ranging from 30 V to 100 V.

To compare the switching speed capability of devices from these two generations of eGaN FETs we need to look at the specialized Figure of Merit (FOM_HS) used by designers of DC-DC converters. For this figure of merit, lower values translate into lower power losses during each switching cycle, thus enabling higher circuit frequencies. As shown in figure 3, the new generation product is about twice as good as the prior generation.

These two attributes, on-resistance and switching performance, translate into more efficient power conversion. To illustrate this point we can use DC-DC converters as a yardstick because they enjoy large markets and have commonly understood metrics.

In figure 4 is a performance comparison between silicon MOSFETs, Generation 2 and Generation 4 eGaN FETs in the two most common types of DC-DC converter; 12 V to 1.2 V, and 48 V to 12 V. Tens of millions of these converters are used each year in servers and telecom equipment and are one of the largest sources of wasted energy in server farms.

The vertical axis of each of these graphs shows the efficiency as a function of current (horizontal axis). In both cases, the eGaN FET-based converters greatly outperform the MOSFET-based converter, showing a 30% improvement in 12 V – 1.2 V converters and a 44% in 48 V – 12 V converters. The Generation 4 eGaN FETs increase the performance gap compared with silicon-based MOSFETs by about twice the amount as the Generation 2 devices. The performance gain due to eGaN FETs compared with silicon-based MOSFETs can be translated into more than a doubling of the value of the DC-DC converter – thus resurrecting semiconductor’s adherence to Moore’s Law.

Doubling End User Performance Too

The real implications of this doubling of performance is far more profound than just a doubling of the value of DC-DC converters. Over the last few years the Generation 2 devices enabled new applications that were known but dormant until these eGaN transistors were invented and could achieve a quantum change in performance. Now, true to Moore’s Law, the doubling of performance of Generation 4 eGaN transistors will similarly spur innovation, move the technology up the learning curve, and open new applications for products that need to be even smaller, lighter weight, and lower cost.

As our understanding of GaN continuously matures, the technology is surging forward, well ahead of EPC’s original timetable. eGaN integrated circuits originally targeted for 2016 actually launched in September of 2014; Generation 5 eGaN FETs are expected in early 2016, with Generation 6 coming in 2017 – which is even faster than Moore’s Law! eGaN technology is expected to expand well beyond the confines of the $12B discrete transistor market to the $30B power management market, the $40B analog IC market, and conceivably the entire $300B semiconductor market.

This is just the beginning…