GSWP100W-EVBPA
GaN E-HEMT Wireless Power Transfer Evaluation Board
User’s Guide
_____________________________________________________________________________________________________________________
GSWP100W-EVBPA Rev 180529
© 2018 GaN Systems Inc.
www.gansystems.com 22
Please refer to the Evaluation Board/Kit Important Notice on page 26
PA Performance with EMI filter
Power-on Procedure with EMI filter
•
An additional heatsink may be required. The PA heatplate is provided with threaded hole
locations that can be used to attach the heatsink to the heatplate with 4-40 screws. To ensure
excellent thermal conduction, apply thermal grease to the PA / heatsink interface before
screwing the units together. Enough thermal grease should be applied so that a small amount
extrudes on all four sides as the screws are tightened. Wipe the assembly clean.
•
Make sure jumpers JP43/JP44 are on
•
Do not attach a cable or wire to JP56.
•
Connect the load to JP57.
•
Plug 5V
DC
supply into JP35. Pin 1: positive. Pin 2: negative. Adjust the voltage to 5V.
•
Plug the HV supply into JP32. Pin 1: positive. Pin 2: negative. Turn the supply on and ramp the
voltage from 0V to 10V
•
Monitor the test point voltage by comparing the power meter measurement to GaN Systems’
test data which is available in Appendix A.
•
If the measurements correlate, increase the HV supply to 28V
DC.
•
IMPORTANT: Ensure the 5V
DC
supply does not exceed 6V during testing.
•
The optimized impedance of the current mode PA is around 30
Ω. Using a
50
Ω
load will not
cause damage, however, the system will operate at a lower efficiency.
Evaluation Results-with EMI filter
For improved EMI performance, a filter can be used to reduce the higher order harmonics in each side of
the push-pull arm. Also, the addition of an EMI filter converts the PA from operating in voltage mode to
current mode, which provides a constant current for the WPT system.
The frequency spectrum of the PA is depicted in Figure 22. The 3rd harmonic rejection is around -58dBc,
with more than -60dBc rejection on high order harmonics. This outstanding performance will greatly help
the WPT system level EMI performance.
