BJT_Formulas_b

BJT_Formulas_b - qV EB / kT 1 1 sinh( W / L B ) e qV CB /...

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Bipolar Junction Transistors (BJTs)
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I En = q A D E L E n E0 e q V E B / k T 1 I Cn = – qA D C L C n C0 e q V C B / k T 1 pnp BJT – Electron currents in p-regions W 0 I B1 I B3
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pnp BJT – Case 1: No Recombination in Base p B ( x ) = p B (0) + p B ( W ) – p B (0) x W I Ep = q A D B (n i 2 / N B ) [ ( e q V EB / kT -1 ) - ( e q V CB / kT -1 )] / W I Cp = I Ep (for the specific case of no recomb in base) I Ep = q A D B x [ - ( p B (W) – p B (0))] /W W << L B I B2 = 0
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Gain Components – for “forward” bias γ : Emitter Injection Efficiency = I Ep / (I En + I En ) γ = ( D B / N B W) / [ (D E / N E L E ) + (D B / N B W) ] γ = 1 1 + D E D B N B N E W L E
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Gain Components – for “forward” bias α T : Base Transport Factor = I Cp / I Ep for special case of no recombination in base: α T = 1
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Gain Components – for “forward” bias α DC = I C / I E 2245 I Cp / (I Ep +I En ) α DC = ( I Cp / I Ep ) x ( I Ep / (I Ep +I En )) = α T γ for special case of no recombination in base: α DC = γ = 1 1 + D E D B N B N E W L E
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Gain Components – for “forward” bias β DC = I C / I B = I C / (I E - I C ) = α DC / (1 - α DC ) for special case of no recombination in base: β DC = ( D B / N B W) / (D E / N E L E )
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I Ep = qA D B L B p B0 cosh( W / L B ) sinh( W / L B ) e
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Unformatted text preview: qV EB / kT 1 1 sinh( W / L B ) e qV CB / kT 1 I Cp = qA D B L B p B0 1 sinh( W / L B ) e qV EB / kT 1 cosh( W / L B ) sinh( W / L B ) e qV CB / kT 1 pnp BJT Case 2: Recombination in Base p B ( x ) = p B (0) sinh[( W-x )/ L B ] sinh( W / L B ) + p B ( W ) sinh( x / L B ) sinh( W / L B ) W &lt; L B (but not &lt;&lt;) I B2 = I Ep- I Cp Gain Components for forward bias T : Base Transport Factor = I Cp / I Ep with recombination in base: T = 1 / (1 + 0.5 x W 2 /L B ) = 1 1 + D E D B N B N E W L E T = 1 1 + 1 2 W L B 2 dc = 1 1 + D E D B N B N E W L E + 1 2 W L B 2 dc = 1 D E D B N B N E W L E + 1 2 W L B 2 p B ( x ) = p B (0) + p B ( W ) p B (0) x W Fig. 10.5 (Graphical Identification of Biasing Modes) Fig. 10.7 (BJT Electrostatics)...
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BJT_Formulas_b - qV EB / kT 1 1 sinh( W / L B ) e qV CB /...

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