anyone know where to get any mosfets with a floating base terminal?

I can't seem to find any, the only 4 pin i could find was the STW69N65M5-4, which doesn't seem to truly have a floating base, just 2 sources

I just wanted to try messing with biasing, and had trouble finding any

 

Does MOSFET has a base ?

Mr. Magnet, are you referring to GATE ?

 

Only 4 terminal I have is 2N3821, N ch J FET, with gate leakage of .1 ηA, so it couldent have too much tied to the gate.

 

Does MOSFET has a base ?

Mr. Magnet, are you referring to GATE ?

I just learned that mosfets are 4 terminal devices, they usually just have the body silicon connected to the source for reference bias







I'm trying to find one that doesn't have the body/casing connected to the source

@Bernard, thanks, that MIGHT be what I'm looking for, I can't tell byt the datasheets I found if the body pin is explicitly for the internal silicon, or a way of connecting to the physical casing
(no datasheets I saw had a diagram, I didn't dig too deep yet though)

Moderators note : inserted images , used upload to forum

 

dual gate mosfets were fairley common in rf stuff, lookup the 40673 for an example. they actually used both gates, one for normal input, and the other for controling gain. I have never seen a high power dual gate mosfet.

 

2N3821, bottom view, CW from tab, S, D, G, C for case & measured 0 Ω.

 

I found some modern dual gates, like the NTE222



which are interesting, but the 2n3821 is still the only thing I've seen that might be an actual connection to the silicon body.
I might get some to play with and see, I can't seem to find a good diagram of what the case is connected to

 

the 2n3821 is a jfet, not a mosfet.

 

the 2n3821 has the case connected to a lead. if you ground it, it grounds the case, shielding the jfet. it is generaly used for low level rf amplification.

 

Are you talking about a mosfet in an "iso-top" case? They have four leads available, and the base is isolated/insulated. But the don't have leads like a regular mosfet, they have screw terminals instead. A standard every day mosfet has four leads but the tab is the other lead/source and has to be insulated.


Here's an example of the type -