Stray inductance in the source lead will cause oscillation problems,
even the inductance of a 0.1 ohm resistor.

When the gate turns on, the dVdT at the source lead may be faster than
it is a the gate. If so, the transistor will turn back off, lowering
the voltage on the source, lather rinse and repeat...

It's fun in analog land!
--=20
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