Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How to bias a transistor into cutoff

  1. Aug 4, 2011 #1
    hi
    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:
    Vth=Rth*Ib+0.9+Ie*R12
    and output equation is:
    5=Vce+Ie*R12

    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

    berkeman

    User Avatar

    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
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: How to bias a transistor into cutoff
  1. Transistor biasing (Replies: 6)

  2. Transistor biasing (Replies: 11)

Loading...