dual base transistor?

[coppercone2]

I found a dual gate MOS transistor. Ok, it looks interesting to play with one day.

Dual gate transistors look to be mainly RF type devices.

But I wondered if it has a counterpart, i.e. a Dual base transistor. 

the symbol exists on german wikipedia

[IconicPCB]

Dual gate fet is actually a cascode kind of structure where the lower transistor drain drives the source of the upper device typically used in RF work. The BJT equivalent is similarly structured such that the lower discrete transistor drives the emitter of the upper transistor.Upper transistor operates in common base configuration and presents a low impedance load to the lower device minimising  deleterious effects of Miller capacitance. I have not come across a dual base cascode single package device.

[guenthert]

Well not quite a dual-base transistor and won't match the given symbol, but there are (or were) unijunction transistors (e.g. 2N2646).

[Kleinstein]

I also have not seen cascode connected dual BJTs as the equivalent to a dual gate MOSFETs. There are JFET+BJT hybrids however.

Inside ICs there are also dual emitter/collector transistors, with the emitter or collector split to different parts. These were used in some TTL gates and are used for current mirrors. I have not seem them as discrete parts.

[coppercone2]

I thought they were like this.

[voltsandjolts]

Note the internal connection between gate 1 and gate 2 in your second picture, which just makes a standard fet, with improved characteristics.

[coppercone2]

Oh I thought it was more clear, but I think they have isolated ones? Or are all the isolated ones cascode structure?

I only found it interesting because I thought they had separate drivers