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Cs_mosfet amplifier

  1. Apr 8, 2014 #1
    Hi all,

    I am studying cs_mosfet amplifier and i have simulate one simple amplifier with VDD=+12v Vs=1v ID=0.5mA gm=1mA/v Vd=6v. I am getting a signal that is amplified by gain -11.3 by calculation and also on simulation but when doing on hardware i am getting gain around -40 to -45
    I am using Bs 170 mosfet.

    I have tried various combination of capacitors but still gain comes around -40......can anybody suggest me where is the mistake?
  2. jcsd
  3. Apr 8, 2014 #2
    can anybody tell me how to attach file here?
  4. Apr 8, 2014 #3
    How can you be sure that your real MOSFET Bs170 will indeed have gm = 1m?
    Do know how to measure Vgs(th) and how you can find K - factor ?

    PS Go advanced ---> Attach Files
    Last edited: Apr 8, 2014
  5. Apr 8, 2014 #4


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    Science Advisor

    Can you verify you are using the correct transistor?

    Can you verify you are using the correct resistor?

    Have you verified the DC operating point?
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