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How to bias a transistor into cutoff

  1. Aug 4, 2011 #1
    i would like to bias a transistor into cutoff. i have the schematic shown below and for the transistor i am using it has a collector cutoff current at 100nA. so my approach was frist to perform Dc analysis:

    Vth=5*(R10/(R10+R4)) Rth=(R4*R10)/(R10+R4)

    so my input equation is:
    and output equation is:

    i would ussually say Ie=Ib+Ic=(B+1)Ib but i dont think this equation holds at cutoff so should i assume Ic>100nA like 105nA so the amplifier will be in the active region(so i can use Ic=B*Ib) and then increase resistance values so Ic<100nA and the transistor will be in cutoff please help!
  2. jcsd
  3. Aug 4, 2011 #2


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    Staff: Mentor

    Looks like the schematic did not post. Can you try again? What is the application for the circuit?
  4. Aug 5, 2011 #3
    ops i taught i attached it. anway i figured it out, it is used for RF applications
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