140b midterm 2 cheatsheet

140b midterm 2 cheatsheet - Hole Diffusion Current Density...

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Unformatted text preview: Hole Diffusion Current Density in the base J p (x b ) = eD B dp B /dx = eD B p B (0)/x B use x B *10-4 when you have μm p B0 =n i 2 /N B p B (0) = p B0 exp(V EB /V t ) n B0 =n i 2 /N B n B (0) = n B0 exp(V BE /V t ) x B = metallurgical base width - x n (for pnp BJTs) = metallurgical base width – x p (for npn BJTs) 2 / 1 2 / 1 1 ) ( 2 BJT) ( 1 ) ( 2 + + = + + = C B B C R bi s d a d a R bi s n N N N N e V V pnp N N N N e V V x ε ε 2 / 1 2 / 1 1 ) ( 2 BJT) ( 1 ) ( 2 + + = + + = C B B C R bi s d a d a R bi s p N N N N e V V npn N N N N e V V x ε ε = 2 ln i D A t bi n N N V V V R = V BC (pnp) = V CB (npn) Estimating the Early Voltage: lowest highest V lowest highest J npn V J pnp V J V J g CB p CB p BC p EC p- = ∆- = ∆ ∆ ∆ = ∆ ∆ = ∆ ∆ = ) ( ) ( ' BJTs) (npn ) ( BJTs) (pnp ) ( A CB A BC p V V g V V g J + = + = Maximum base doping considering bandgap narrowing...
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