GS66504B-EVBDB 650V
GaN E-HEMT Evaluation Board
User’s Guide
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GS66504B-EVBDB UG rev. 161120
© 2016 GaN Systems Inc.
www.gansystems.com 6
Please refer to the Evaluation Board/Kit Important Notice on page 29
Current shunt JP1:
The board provides an optional cuwwwrrent shunt position JP1 between the source of Q2 and
power ground return. This allows drain current measurement for switching characterization test
such as Eon/Eoff measurement.
The JP1 footprint is compatible with T&M Research SDN series coaxial current shunt
(recommended P/N: SDN-414-10, 2GHz B/W, 0.1Ω)
If current shunt is not used JP1 must be shorted. JP1 affects the power loop inductance and its
inductance should be kept as low as possible. Use a copper foil or jumper with low inductance.
CAUTION:
Check the JP1 before the first time use. To complete the circuit JP1 needs to
be either shorted or a current shunt must be inserted before powering up.
Figure 6 Current shunt position JP1
Measurement with current shunt:
1.
When measuring VSW with current shunt, ensure all channel probe grounds and current shunt
BNC output case are all referenced to the source end of Q2 before the current shunt. The
recommended setup of probes is shown as below.
2.
The output of coaxial current shunt can be connected to oscilloscope via 50Ω termination
impedance to reduce the ringing.
3.
The measured current is inverted and can be scaled by using: Id=Vid/Rsense.
Current
Shunt
Q2 Source
VDC-
