Calculating fmax of bjt. (cjc from doping levels ?)

Discussion in 'Homework Help' started by mikey20, Dec 17, 2012.

  1. mikey20

    Thread Starter New Member

    Dec 17, 2012
    1
    0
    Hi. Could you help me with one problem that seemed too difficult for me?
    Given that Nd=10^16/cm^-3 , Na=10^14/cm^-3 , β(ω=300MHz)=60, Vcb=10 V, rbb=20 ohms,
    calculate the ωmax (fmax ?) of a bjt ?
    I am struggling to find a proper equation to obtain Cjc from Nd and Vcb, but i'm not even sure if it's possible.
    the other problem : find differential conductance of a pn junction, given that I=50mA , electron lifespan: 1us. Does the electron lifespan change anything or influence the diff. conductance ? thanks in advance
     
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