121B_1_bjt

E jason woo 0 1 0 18 ee121b spring 2010 now using

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Unformatted text preview: all for large V BE But can be much large than 0 for small VBE Jason Woo 20 EE121B Spring 2010 log I IC InE IBIPE+Irec IPE dominates Irec dominates VBC<0 VBE Jason Woo 21 EE121B Spring 2010 Next, we consider I nC I n (WB ) = I nE I n ( 0 ) This is called the base transport factor, T T Now I n ( W B ) I n ( 0 ) T = I n ( W B ) I n ( 0 ) = 1- ( I n ( 0 ) - I n (WB ) ) I n ( 0 ) i.e., T is the percentage of injected electrons in the quasi-neutral base region that do not recombine with the majority carriers. Jason Woo 22 EE121B Spring 2010 Using the equations for In(WB) and I0(W0) , we therefore have: WB csech WB LB T = sech WB LB coth LB 2 WB 1- 2 2 LB In general, since J n - q n = - qRn = n x J n (W B ) - J n ( 0 ) = -q WE 0 ndx n if WB LB , T 1 Jason Woo 23 EE121B Spring 2010 Next, let us consider Recall I C I nC I C = I nC + I pC - I rec = I nC + I pC + I gen Again, under normal mode operation qDC N DC I p ( xC ) + A LC * - I rec is small I n ( 0 ) ( ) * * is also small since I rec =...
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This note was uploaded on 06/01/2010 for the course EE EE161 taught by Professor Wang during the Spring '09 term at UCLA.

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