GSWP100W-EVBPA
GaN E-HEMT Wireless Power Transfer Evaluation Board
User’s Guide
_____________________________________________________________________________________________________________________
GSWP100W-EVBPA Rev 180529
© 2018 GaN Systems Inc.
www.gansystems.com 19
Please refer to the Evaluation Board/Kit Important Notice on page 26
Figure 18 •
Oscilloscope Plot Showing Both GS61008P Drain Node Signals
The ratio of maximum Drain voltage and input DC voltage is 2.33 which is ideal for a class EF2 amplifier.
This operating condition eliminates voltage stress on the transistors and has low second harmonics. The
output current shown in green, is not a perfect sinewave due to high order harmonics on the output load.
Switch mode Power Amplifiers have a lot of harmonics at the output. One significant advantage of the
Class EF2 topology is that it has a lower 2
nd
harmonic when compared to other PA topologies. This
advantage results in a Class EF2 PA with much better EMI performance.
Figure 19 shows the spectrum of the PA at 100W output power without an EMI filter. Compared to the
fundamental frequency, the 2
nd
harmonic is -35dBc, the 3
rd
harmonic is -20dBc, and the 4
th
harmonic is -
34dBc. This extremely low 2
nd
harmonic performance makes it much easier to filter out the PA’s high
order harmonic. This allows designers to meet EMI specifications and regulations without additional cost.
The PA’s output power and efficiency are shown in Figure 20. This PA delivers 93% efficiency at 100W
output power and 27V
DC
input voltage. This remarkable efficiency performance makes PA the best
candidate of the WPT systems, and particularly advantageous for high power applications such as drone,
autonomous robot and E-bike charging.
