I'm wanting to make a high frequency supply square wave - around 450Vac at 1MHz - 40mA, The voltage is pretty easy, it's the switching I'm trying to get my head around. I'm using a CCFL board to generate the high voltage bit - it does it at 50kHz. So I was then thinking of turning that into DC and chopping it up with an H-Bridge I've found a transistor that might do the job a BSP135 its a small signal transistor 600V 100mA and rise/fall times around 10-20ns.

However I'm not sure how to power the high side of the H Bridge - I would use opto couplers but they dont respond fast enough.

I was going to use the clkout on my pic and some ttl logic devices to trigger the bridge. But getting that high voltage is difficult.

The other way I've thought of is rewinding the transformer to a center tap and run a +ve and -ve voltage through a half bridge using a PNP on top and NPN on bottom and a couple of 200V zeners between clkout (based around 0v) and the base legs. It would be problematic as it would not allow me to vary the supply voltage as I'd like, and would need fine tuning before it worked (could boost the voltage of the CLKOUT a certain amount with a comparator to help a limited amount).

Any other suggestions or ideas would be greatly appreciated.

Thanks