LTSPICE Question for MOSFET

Discussion in 'Homework Help' started by KaiL, Aug 16, 2016.

  1. KaiL

    Thread Starter Member

    Aug 30, 2014
    57
    0
    [​IMG]

    Addition information
    • Maximum voltage for both Vds and Vgs are 3V.
    This is my circuit.
    [​IMG]

    In LTSPICE , I set 3V for both Vds and Vgs .
    I am also required to extract the threshold voltage. In order for me to find the threshold voltage , am i correct to say that I set Vbs = 0 in LTSPICE?
    Then once I am done for the first part I set Vbs = -0.5V to find the threshold voltage of NMOS.

    [​IMG]
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,973
    3,219
    To determine the threshold voltage you can set Vgs to generate a ramp voltage and then observe Ids to determine when the specified threshold current is reached.
     
  3. KaiL

    Thread Starter Member

    Aug 30, 2014
    57
    0
    Thank you very much for your reply.
    Before I generate the ramp voltage to find the threshold voltage , I set the Vbs = 0 then observe IDs to find threshold voltage.
    Thereafter I have found the threshold voltage for Vbs=0 , I set Vbs = -0.5 and generate the ramp voltage again to find the threshold voltage when Vbs=-0.5. am I correct?
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,973
    3,219
    That sounds correct.
     
  5. KaiL

    Thread Starter Member

    Aug 30, 2014
    57
    0
    Ok thank you very much
     
  6. Bordodynov

    Active Member

    May 20, 2015
    637
    188
    alternative method. Controlled source replaces the operational amplifier.

    Vto.png
     
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