Power Electronics: Re-Invented

Editor's note: I am pleased to bring you a new blogger on Planet Analog. Gene Sheridan will bring us unique and insightful tech aspects of the GaN Power element.

Thirty years ago the power electronics industry experienced an extraordinary and disruptive change. The development of commercial power MOSFETs, combined with switching regulator topologies, challenged the dominance of traditional linear regulators which had utilized bipolar transistors since the beginning of the electronics era. MOSFET-based switchers offered the promise of higher efficiencies, higher densities and possibly even lower cost… but initially they were complex to design and the power industry was unfamiliar with these new “fast” converters.

As analog application-specific ICs were developed by Silicon General, Unitrode & others, these complex designs become simplified, cost-effective and the design community eventually embraced them fully. The rest, as they say, is history… in the following decade, from 1975 to 1985, the power supply industry experienced a 5x increase in power density, a 5x improvement in energy savings and a 3x reduction in costs – a pace of change that has not been repeated in the following 3 decades.

Switching regulators had been around for many years but required the invention of a fast transistor technology and new ASICs to simplify designs and lower costs before they became mainstream. The power industry is at the forefront of another, very similar disruptive transition. Resonant topologies have also been around almost as long as electricity has been available to use, but their adoption has been limited to a relatively narrow application space.

With the invention of commercially-viable GaN power transistors, resonant circuits can enable a dramatic increase in switching frequencies while increasing energy efficiencies compared to hard-switching topologies, creating the potential for another dramatic increase in power densities. However, past resonant designs were complex and expensive. Some, such as LLC and active clamp flyback converters, require a second high-performance transistor and fast high-side level-shifters & gate-drivers to create zero voltage switching (ZVS) over the full operating range.

Now, just as analog ASICs simplified and lowered costs of the early switching regulators, GaN power ICs are available to integrate the high-side switches, fast level-shifters & other critical analog circuits to simplify high-frequency resonant designs and deliver system costs that are lower than their low-frequency, hard-switching counterparts. The combination of resonant topologies, fast GaN transistors and GaN analog integration completes the needed trifecta and we are poised for another decade of extraordinary change in power electronics. Stay tuned for more … this will be a fun ride!!

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