Page 24 - EE Times Europe Magazine | June2020

24 EE|Times EUROPE

GaN HEMTs Outperform MOSFETs in Key Growth Applications

single-transmit amplifier solution that
can wirelessly charge devices regardless of
the standard used in the receiving device.
Wireless charging systems that rely on the
Qi standard operate by inductive coupling at
frequencies in the 100- to 300-kHz range.

AUDIO APPLICATIONS
The lower power dissipation of Class D audio
systems produces less heat, saves space and
costs for printed circuit boards, and extends
battery life in portable systems. Now that
GaN-based HEMT devices with much better
physical properties have become a reality,
a leap in Class D amplifier performance is
on the doorstep. The low resistance and low
capacitance of eGaN FETs offer low transient
intermodulation distortion. Fast switching
capability and zero reverse-recovery charge
enable higher output linearity and low
crossover distortion for lower total harmonic
distortion.
“The first Class D amplifiers were designed
for cars, because they wanted to have more
speakers and more power in cars,” said Lidow.
Figure 7: EPC2037 enhancement-mode power transistor (Image: EPC) “Class A amplifiers were just too big to pro-
duce more than about 25 W and still fit in the
dashboard. Class D was first introduced in the
1980s and enabled cars with 16 speakers and
250 W of power. Its sound quality, however,
was never as good that of a Class A ampli-
fier. That’s because MOSFETs can’t switch
fast enough, and therefore, the relatively
low switching frequency means relatively
poor-quality reproduction. And with GaN
devices, of course, you can go to much higher
frequencies.”
SPACE APPLICATIONS
Enhanced-mode GaN is widely used in device
development for space applications. Com-
mercial GaN power devices offer significantly
higher performance than traditional
radiation-hardened devices based on silicon
technology. This allows the implementation
of innovative architectures with applications
Figure 8: Isolated power-conditioning unit, the Cesium PCU-1C28, designed with EPC on satellites, data transmission, drones,
devices (Image: EPC) robotics, and spacecraft.
Smaller than equivalent MOSFETs, eGaN
FETs provide radiation tolerance, fast switch-
WIRELESS POWER by the generator must reach the receiving ing speed, and improved efficiency, leading to
“Wireless energy is ready to be incorporated device. Magnetic resonance technology is smaller and lighter power supplies (smaller
into our daily lives,” Lidow said. Transmitters the linchpin to ubiquitous implementation, magnets and reduced heat sink size or even
can be placed in furniture, walls, and floors enabling transmission over large areas, spatial elimination of heat sinks in many cases).
to power or charge electronic and electrical freedom for positioning reception devices, Faster transient response can also reduce
devices efficiently and economically over and the ability to power multiple devices capacitor size. Using these FETs, power supply
large areas and across multiple devices. simultaneously. designers have the choice of increasing the
Wireless energy transfer has been studied EPC offers a full range of transmitter and frequency to allow smaller magnets, increas-
for more than 100 years; in fact, the con- receiver reference designs from single device ing efficiency, or designing a satisfactory
cept dates back to the invention of the Tesla charging to multiple devices powered simul- balance of both. ■
coil. A key factor in making viable wireless taneously across a large surface area. GaN
energy transmission systems viable is effi- enables high efficiency for both the low- Maurizio Di Paolo Emilio is a staff
ciency: To define such a system effectively, frequency (Qi) and high-frequency (Air- correspondent at AspenCore, editor of Power
a large portion of the energy transmitted Fuel) standards, supporting a lower-cost, Electronics News, and editor-in-chief of EEWeb.

JUNE 2020 | www.eetimes.eu