GSWP100W-EVBPA
GaN E-HEMT Wireless Power Transfer Evaluation Board
User’s Guide
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GSWP100W-EVBPA Rev 180529
© 2018 GaN Systems Inc.
www.gansystems.com 3
Please refer to the Evaluation Board/Kit Important Notice on page 26
Introduction to Magnetic Resonant Wireless Power Transfer
Recent technological advances in power semiconductors are enabling Wireless Power Transfer
(WPT) as a technically and commercially viable option for charging and powering equipment
across a wide range of markets, applications, and power levels.
Inductive charging has been in use for a number of years, however, it’s burdened with limitations
that restrict it to low power applications with tightly controlled alignment between the transmitter
and receiver.
A more advantageous approach, magnetic resonant charging, addresses these shortcomings by
using a high frequency oscillating magnetic field to transfer energy. The benefits that magnetic
resonant charging offers include variable spacing between the transmitter and receiver, the ability
to charge through materials such as a desk or an enclosure, one-to-many charging, ease of
installation, suitability for high power levels, and fast charging. Table 1 provides a comparison
between inductive charging and magnetic resonant charging.
GaN E-HEMTS are a key enabler of magnetic resonant charging because their extremely fast
switching speeds, on the order of a few nanoseconds, result in very low switching losses. This
allows them to operate efficiently at very high frequencies, such as the 6.78MHz that is commonly
used for magnetic resonant charging.
Table 1
A comparison of Inductive charging and Magnetic Resonant charging
Charging technology
Inductive
Magnetic Resonant
Frequency range
80-300kHz
6.78MHz
Max transfer range
5mm
50mm
Multi-device
No
Yes, at different power levels
Spatial Freedom
Low
High
Power Range
Low & limited
30W max
Broad & versatile
50W to 20kW+
Efficiency
Limited to 80%
High: up to 95%
A high-level block diagram of a resonant wireless power transfer system is shown in Figure 1. The
transmit section is composed of a power amplifier, an impedance matching circuit and a transmit
coil. High frequency energy is transferred wirelessly at 6.78MHz to the receive circuit which is
comprised of a receive coil, an impedance matching circuit and a rectifier.
The GSWP100W-EVBPA evaluation board is designed to support and expedite the innovation of
WPT systems by providing the Power Amplifier, the most challenging aspect of the system design.
