Low power (ultra) high voltage MOSFET

I don't thuink there are any they meet this. You may have to build some sort of cascode circuit. Mosfets like the DN3145 from Supertex would allow a few hundred volts per stage of the cascode. Depletion mode devices have advanages in the later stages of a cascode. You can make their gate voltages from the drain voltage of the last device. This makes for good sharing of the power all the way down to ground.

Thanks for your comment!

I did indeed some experiments with two 1200V (enhancement) Mosfets in a cascode like circuit, but has resulted in a rather complicated circuit. I was wondering whether anyone on this forum would know about different devices. It would simplify the circuit tremendously. Thanks again, Ad

Maybe check out tube technology.. D from BC

Hi Ad,

OK, not exact fit but may be ;-)

look to

OK it is built for 19 A but the rest may be OK :-)

Marte

Hi Marte,

Thanks for the info! I have spoken to the rep here in the Netherlands about these devices (IGBT) but they accept only a minimum order of 24 pieces costing about $105 each. This is beyond my budget.... Anyway, thanks very much and I will try to find another supplier with a more appropriate offer.

Best Regards, Ad

Sounds like a job for a tube. Last time I needed to do this sort of thing I used an 811A--I really really needed low capacitance as well--about 5 pF iirc. That was in about 1990, not 1960, btw. Tubes are really amazing for that sort of job--they're not only for separating fools from their money.

Cheers,

Phil Hobbs

Hi Phil,

Thanks for the advice. I am really going to look for the tube solution, although I am not very familiar with using tubes. Perhaps a nice time to learn something new... Thanks again, Ad

Hi Ad,

Uff, few years ago I got samples for 20 EUR/piece. They told me that the price in series production would be in this range, too. If you don't need too much switching speed then you could use a series connection. What's your goal? May be I can help more when I know what you want to do. You may write me a mail. I'm not every day here, because there is too much offtopic nowadays :-(

Marte