FDV304P's forward biased protection diode causing channel opening

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#1

Hello guys, I have observed a strange behavior on P-channel logic-level mosfet FDV304P with a built-in GS protection Zener diode.
When Vgs is in a negative region, the transistor is behaving as expected.
With Vgs=0V, the Idss is around -1uA, as expected.
With Vgs=+1V, the channel closes a little bit more, Id ~ 0uA, as expected.
But with the Vgs>+1.4V (protection diode forward biased, gate current limited with resistor), the channel starts conducting. It looks like the Id is mirroring the forward current of the diode between GS (so it behaves like a BJT with beta ~ 1). It doesn’t look like a parasitic diode between GD because when I increase the source resistor value, the Id drops.

Can someone please explain what’s happening?

#2

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