N Mosfet gate source voltage

Discussion in 'General Electronics Chat' started by Humanityrulz, Nov 1, 2010.

  1. Humanityrulz

    Thread Starter Active Member

    Jul 21, 2009
    I am using ZVN3306A mosfet, mosfet driansource voltage is 9V and gate source voltage is 5V , I expected the voltage at C1 around 5V but it's not , it's giving max 3V ?
    When I gave the 9V pulse at gate , at C1 it's giving 9V.
    (data sheet mentioned gate source threshold voltage is 0.8V to 2.4V )

    Is there any mosfet(fast switching) to resolve issue?

    My second question is I want amplify the 5v pulse(from PIC) to 9V (frequency of the pulse is 10kHz,width is 2% only) will opamp recognise the 2% width of the pulse and amplify that pulse to 9V?
    is there any better way to amplify these type pulses other than Opamp?

    Thanks in Advance.......:)
  2. SgtWookie


    Jul 17, 2007
    I'm not exactly sure what you're wanting to do with your circuit.

    Are you using a 9v "transistor" battery to power your circuit?

    When the MOSFET is on, it's sinking 90mA current through the resistor. That's a pretty heavy load for one of those batteries.

    I simulated your circuit using a 2N7000 MOSFET, which has somewhat similar characteristics. I've found with those MOSFETs that I usually have to hand-pick them when using them with logic levels on the gate, as some have higher threshold voltages than others.

    Most typical hobbyist-type opamps won't have enough bandwidth to amplify a signal like you're wanting to produce; the slew rate would have to be quite high.

    What is your output signals' current requirement?
    Does the signal have to go all the way from 0v to 9v?
  3. shortbus

    AAC Fanatic!

    Sep 30, 2009
  4. SgtWookie


    Jul 17, 2007
    The datasheet also shows "typical" characteristics for various Vgs. Note that the "typical" characteristics are not "guaranteed" characteristics. Your mileage may vary.
  5. Audioguru


    Dec 20, 2007
    You don't know how good is the Mosfet you buy. It might be very good or barely passing or anywhere in between.

    If you design your circuit for a good one then it won't work with millions of lesser ones.
    Do you want millions of failing circuits?

    Simply design your circuit so it works with any passing transistor.
  6. Humanityrulz

    Thread Starter Active Member

    Jul 21, 2009
    Thankyou all for your suggestions.....
    Hi SgtWookie thanks for response.......
    1) Yes I am...using 9V battery....
    2) Can you suggest me about to draw less sinking current...!
    I found micropower high side mosfet driver but it's expensive..please find attched datasheet.

    3) Thanks for info.... I decide to use mosfet driver instead of amplifier.

    About simulation you attched.. I didn't get it......what you'r trying to tell me(abt characterstics..).......sorry..

    Hi Shortbus Thanks for info....

    Hi Audioguru thanks for suggestion.. Using transistor is not problem but finding the right one for my application is an issue.. I need high speed switching transistor.... with low power consumption.... can you suggest me...!!!!
    I will try to find suitable transistor anyway......