fest FET?

Discussion in 'General Electronics Chat' started by mainsys99, Oct 12, 2017.

  1. mainsys99

    Thread Starter New Member

    Oct 11, 2017
    4
    0
    I need fest speed FET?!
    I use 100MHz PWM( 50%/50%) and control FET.
    Help me!
     
  2. bertus

    Administrator

    Apr 5, 2008
    17,155
    3,015
    Hello,

    Why do you need 100MHz for the PWM?
    PWM is normaly done on much lower frequencies from 20kHz upto 2 MHz (as in switching regulators).

    Bertus
     
  3. mainsys99

    Thread Starter New Member

    Oct 11, 2017
    4
    0
    Hello!
    Sorry but, I can not say now.
    The project now requires 100MHz PWM.
    So a fast FET is needed.

    Tgier.LEE
     
  4. crutschow

    Expert

    Mar 14, 2008
    16,569
    4,475
    Can you tell us at what voltage and current?
     
  5. BobTPH

    Active Member

    Jun 5, 2013
    906
    161
    More important than the speed of the FET is the gate driver. To switch at very high speed, you need a gate driver that source and sink a lot of current. The higher current capability the FET has, the more charge it tends to need on the gate, and it takes current to supply that charge quickly.

    Oh, and by the way, suppressing RF emission is going to a be a problem. 100MHz is right in the middle of the FM broadcast band.

    Bob
     
  6. mainsys99

    Thread Starter New Member

    Oct 11, 2017
    4
    0
    I will use 9V 15A and control 100MHz PWM.
     
  7. crutschow

    Expert

    Mar 14, 2008
    16,569
    4,475
    15A @ 100MHz! :eek:
    That will take some serious design effort and a lot more than just a fast FET.
    Why 9V?
    What does the load look like?
    It it just resistive, or does it have capacitive and/or inductive elements?
    Can it be floating or does it have be grounded?
    How far is the load from the circuit?
     
  8. mainsys99

    Thread Starter New Member

    Oct 11, 2017
    4
    0
    It is just like switching an LED with a FET.
    9V is an external power source.
    There is no other circuit, just like the LED only switch.
     
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