IEEE Power Electronics Magazine - June 2022 - 32

capability but then had vulnerable exposed gates and a very
low threshold voltage. This made them very susceptible to
noise and voltage spikes due to high-frequency and high dv/
dt noise from the surrounding switched-mode converter
circuit, so required complex and expensive control and
gate drive circuits and introduced further parasitic circuit
elements like resistance and inductance. Both implementations
of d-Mode and discrete-FET e-Mode GaN restricted
the high-frequency performance of the GaN switch, to the
point where there was minimal, if any, advantage over Si, so
limiting market adoption to date.
Introducing Monolithic
GaNFast Power IC
The key to improved performance
(reduced loss, higher switching frequency)
and rapid market adoption
(simple, cost-effective designs) is
to create what approaches the 'ideal
switch', i.e. a circuit building block
which translates a minimum energy
digital input signal into lossless
power delivery. Using lateral e-Mode
GaN, a proprietary technology platIntegration
enables
virtually zero loss in
turn-off because the
gate drive loop has
essentially zero
impedance.
form - GaNFast - has been created which enables the
monolithic integration of drive, logic, protection, and FET
into a GaNFast power IC [4], [5]. This single die can then
be packaged into industry-standard, low-inductance, low
cost, QFN packages for off-line ac or 400 V dc applications.
Integration enables virtually zero loss in turn-off because
the gate drive loop has essentially zero impedance.
With GaNFast, the GaN FET gate is driven safely, precisely,
and efficiently by the integrated GaN driver. Simple,
robust, low-current 3.3 V, 5 V or 15 V signals, from
standard, low cost, low voltage 'no driver' control ICs
are fed directly into the GaNFast power IC for an easy,
low component count design. The waveforms exhibit a
true " textbook " waveshape with very clean rising and
falling edges, no ringing, and extremely fast turn-on and
turn-off propagation delays. Integration eliminates gate
overshoot and undershoot, while zero inductance onchip
insures no turn-off loss. This lack of ringing and
overshoot makes tight control of deadtime easy in halfbridge
circuits. This exceptional level of fast and quiet
switching performance, together with the integrated
gate drive and simple PWM input,
allows for the design of a variety
of different high-frequency power
converters, raising practical switching
speeds more than 10x from
typical mass production 65/100 kHz
to 1 MHz+.
The single-device monol ithic
GaNFast power IC seen in Figure 1
was a huge step for the industry, and
rapidly accelerated the adoption of
GaN in production for high density
flybacks and PFC circuits in mobiledevice
chargers starting in 2018. The next challenge was
half-bridge power stages. Half-bridge circuits are essential
building blocks in the power electronics industry,
used in everything from smartphone chargers and laptop
adapters, motor drives, TVs, solar inverters, data centers
and electric vehicles (EVs). Operating these half-bridge
circuits - i.e. providing bias power and signal to a floating
high-side switch - at very high frequencies can shrink
magnetics and enable a dramatic reduction in size, cost
and weight while delivering faster charging. However,
Wide Range
VCC (10-30 V)
VCC
Regulator
Ensures VGS
Within SOA
1
4
3
VDD
Dz
D
REG
UVLO
8
7
6
5
dV/dt
2
PWM
PWM
Hysteresis
for Noise
Immunity
No Inductance or
Ringing in Gate Loop
FIG 1 The monolithic GaNFast power IC building block.
32 IEEE POWER ELECTRONICS MAGAZINE z June 2022
S
PAD
Protected Gate
(Not Pinned Out)
Total Layout
Flexibility and
Simplicity
UVLO Protects Driver and
FET When Full Power
Unavailable
IEEE Power Electronics Magazine - June 2022

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