Low cap PMOS

This one?

That's an OnSemi/Sanyo part.

Just be careful with product development. Much of the stuff with Japanese ancestry is going unobtanium these days. Digikey has lots of the 5LP01M though.

There's also the uPA610 dual, but also of Japanese origin and it's currently zero stock in the US.

I think so. Thanks.

One thing I didn't notice is that they seem to have built-in awfully high gate resistance... (see the loooong switching times)

That's on account of the built-in gate-source zener. You'll want a FET without that. Slim pickens, as they say over here, not too much to pick from.

If there is the slightest chance to swing this circuit to N-channel then by all means I'd do it.

I have used FDV302P in some cryogenic work, it also has pretty low Ciss.

Regards, Mikko

Mosfet data sheet switch times are generally useless. 2N7002 is spec'd for 20 ns on/off switching 30 volts into 150 ohms. We get under 1 ns switching 50 volts on/off into 50 ohms.

Lots of our products do stuff that data sheets suggest are impossible. You've got to test parts yourself to see what they can really do. Some parts are one to six (or more) orders of magnitude better than the datasheet values, especially for stuff that's hard to test quickly on a production basis.

Ooops, sorry, I read gate capacitance but that's not what you meant.

Ah, I wondered what the zener had to do with the gate resistance :-)