Wide-bandgap MOSFET and diode ringing

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SiCEngineer

Joined May 22, 2019
135
I am using GaN FET's and Silicon carbide diodes in a buck converter simulation in LTSpice. The current through them should be just above 3A, but when I view the waveforms I actually see some ringing on them. The buck converter is hard-switched, but I thought that with these new devices the ringing wouldn't be so bad because there aren't reverse recovery effects in the FET or diodes. My efficiency is still really good, however the current ratings of the devices are exceeded during these switching instants. The FET is blue trace, and SiC diode is the green trace.

Should this be expected? If so, can anyone recommend some low-loss ways to reduce the ringing to acceptable levels?
 

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shortbus

Joined Sep 30, 2009
7,446
Better results if you would show a schematic along with the scope traces. We don't know what you are doing in your circuit without them.
 

ag-123

Joined Apr 28, 2017
40

ci139

Joined Jul 11, 2016
1,177
I use some SiC diodes and GaN FET's. I should maybe post the .lib, .asy files for those also?
what is required is the diagram (image/screenshot)
  • net from Drain to load . . . with anything in it caps. inductors ...
  • the gate config . . . driver signal (everything in between) to gate
  • net from source to supply (if there is anything) also supply resistance and mosfet side (output) *filter caps (or other *-elements)
either ↑that↑ (primary coz everyone is aware of cfg. by)
or→ .asc .lib & .asy to track the connection pin positions ← (or both ←↑ )

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otherwise :: driving the mosfet with too weak signal (with some device models also) results in ringing
. . .
? https://micro.rohm.com/en/techweb/knowledge/sic/s-sic/05-s-sic/7498
 
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