Playing with a switching circuit, yet I seem to have made the observation that these things are fantastic for linear.
Infineon SPA07N60C3, but everyone has their line of SuperJunction MOSFETs.
Circuit, for posterity:
Intended load is high impedance, capacitive. It can easily source 5A peak though.
Since the load is capacitive, it operates in hard switching. The transistors start singing as soon as they get into the Miller plateau. Which in this circuit, I've intentionally exaggerated (27pF D-G), to help keep the transistor voltages matched.
A word about SuperJunction transistors: Coss tanks by two decades, over the5 to 20V range. Very nonlinear, brutal. This is fantastic for switching converters, because it "cushions" the switching edge, doing a better job of snubbing than an external network ever could. By pushing all the Miller effect to the low voltage end, switching loss can be very low.
With stacked transistors, that works against me, because they'll probably be mismatched in the low-capacitance region. So the switching times, and voltages, probably won't be matched, forcing much more voltage across just one over-performing transistor.
So I increase Miller capacitance, so the rise is slower, and more linear.
And to protect against accidental turn-on or damage, due to opposite side hard-switching or output sparks, I put zener diodes on G-S. (Back-to-back pairs, since the drive is transformer coupled.)
I think between the zeners and the Miller cap, I've got a particularly nasty loop that makes a wonderful oscillator. In the 200 to 400MHz region, depending on which transistor you ask.
(Ferrite beads on the gate leads solves the oscillation, more or less.)
I'm definitely going to try an RF amplifier with these, soon. I can't do very much power, because of thermal limitations, and bandwidth won't be fantastic because of the high load resistance versus Coss (note that the load resistance has to be high, i.e. the supply voltage high, and because of power limits, the current relatively low, to stay in the low-Coss range). The useful frequency range seemingly should be worthy of vacuum tubes, though! Assuming lead parasitics don't trash it first, which is likely. :)