1. Limited time only! Sign up for a free 30min personal 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!

Analog electronics (BJT circuit analysis)

  1. Dec 9, 2016 #1
    1. The problem statement, all variables and given/known data
    For beta = 100 and assuming ro is very large, what is the DC voltage at the collector?

    2. Relevant equations
    IB = IE(β+1)

    IC = β*IB

    3. The attempt at a solution
    Since IE = 0.5mA, IB = 0.0505 A
    Then, IC = 5.05 A (which doesn't feel right)
    VC is the same potential across the 30kΩ load?
    I tried doing KCL with those currents (to find the current thought the load resistor).
    Should I not be analyzing the direct circuit--should I make an equivalent T-model?
  2. jcsd
  3. Dec 9, 2016 #2

    Charles Link

    User Avatar
    Homework Helper
    Gold Member

    Your equation should read ## I_E=I_B (\beta+1) ##. Try again. I think you also need to assume ## V_{BE}=.7 \, volts ## (approximately). One hint for you: The capacitors basically block any steady state current trying to go through them so the capacitor is an open circuit for the DC part of the analysis.
    Last edited: Dec 9, 2016
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted