This question is continuation of this question: High Frequency Square Wave Generator

I am trying to drive a 400V supply and 50ohm load with an RF MOSFET which has a rise time of 3-4 ns and fall time of 10 ns.

I need to have fall and rise time no more than 2ns (2ns fall 2ns rise).

Since the voltage is high I couldn't find any MOSFET that fast.

Is there a MOSFET which is capable of reaching this speed, or should I seek another solution for this?

Thanks to comments I am looking for Vacuum Tubes right now. It would be nice if someone suggest me resource about how to select fast rise time vacuum tube.

Duty cycle and frequency are not very important. 50 kHz might be enough. I just need fast rise and fall time.

  • 1
    \$\begingroup\$ Well, what is the limiting factor in your switching speed? Gate capacitance? \$\endgroup\$ Commented Sep 14, 2020 at 13:01
  • 1
    \$\begingroup\$ cascode driven would eliminate any Miller contribution, but 2 ns is still fast for bipolar or FET at that voltage. What about thermionics? \$\endgroup\$
    – Neil_UK
    Commented Sep 14, 2020 at 13:13
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    \$\begingroup\$ Is this actually a continuation of yesterday's question electronics.stackexchange.com/questions/521326/… ? \$\endgroup\$
    – user16324
    Commented Sep 14, 2020 at 13:23
  • \$\begingroup\$ @Brian Drummond yes actually it is. Should I refere my previous question? If yes, I will edit. \$\endgroup\$
    – Ismail
    Commented Sep 14, 2020 at 13:52
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    \$\begingroup\$ @Ismail Thermionics means vacuum tubes in case you did not know \$\endgroup\$
    – DKNguyen
    Commented Sep 14, 2020 at 14:47


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