1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Two stage amp (BJT) homework

  1. May 30, 2017 #1
    1. The problem statement, all variables and given/known data
    see pic in the attachment
    beta = 100
    2. Relevant equations
    Rinput=Rth
    Vinput=VTH
    iB= ic/beta
    IE=ic /alpha
    iB=iE/(beta+1)
    gm=IC/VT
    Avo=-gmRC
    Av=-gm(RC||RL)
    Gv=-Beta[(RC||RL)/Rsig+(beta+1)re
    re=alpha/gm

    3. The attempt at a solution
    solving each stage separately. First DC analysis. open all Capacitors.
    V thevinin can be obtained by voltage divider = 2.88 v
    R input = 31.97 K ohm
    loop between the base and emitter
    2.88-iB (31.97k)-0.7-iB(beta+1)(3.9k)=0
    I have attached a pic of my attempt to solve it. please see attachment 2

    i couldn't complete the solution
     

    Attached Files:

    • 7.jpg
      7.jpg
      File size:
      32.6 KB
      Views:
      35
    • 7s.jpg
      7s.jpg
      File size:
      39.4 KB
      Views:
      29
    Last edited by a moderator: Jun 1, 2017
  2. jcsd
  3. Jun 1, 2017 #2

    NascentOxygen

    User Avatar

    Staff: Mentor

    There is an important "+" sign missing from your first handwritten equation, iB = 2.88 (31.97k .....

    This is something you would have readily discovered by repeating your analysis from scratch. Often that is the most expedient course, when trying to identify ones mistake.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Two stage amp (BJT) homework
  1. BJT homework question (Replies: 1)

Loading...