hw12 - and the amplification factor , assuming the emitter...

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ECE 440 Homework 12 Fall 2009 Due: Friday, Dec 4, 2009 1. Sketch the energy band diagram for an n-p-n transistor in equilibrium (all terminals grounded) and also under normal active bias (emitter junction forward biased, collector junction reverse biased). With the emitter terminal grounded, determine the signs (positive or negative) of the collector voltage V CE and base voltage V BE , relative to the emitter, that correspond to normal bias. 2. A symmetrical p + -n-p + Si bipolar transistor has the following properties: Emitter Base A = 10 -4 cm 2 N a = 4x10 17 /cm 3 N d = 6x10 15 /cm 3 τ n = 0.2 μs τ p = 4 μs μ p = 140 cm 2 /V-s μ n = 1160 cm 2 /V-s μ n = 500 cm 2 /V-s μ p = 420 cm 2 /V-s W b =1 μm (a) Determine if the straight-line approximation can be applied to evaluate the excess carriers in the base region. (b) With V EB = 0.5 V and V CB = - 4 V, calculate the base current I B , assuming perfect emitter injection efficiency. (c) Calculate the emitter injection efficiency
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Unformatted text preview: and the amplification factor , assuming the emitter region is long compared to L n . 3. A Si p-n-p transistor has the following properties at room temperature: n = p =1 s D n = D p =10 cm 2 /s A = cross-sectional area = 10-5 cm 2 N E =10 19 /cm 3 , N B =10 17 /cm 3 and N C =10 16 /cm 3 for emitter, base, and collector doping concentrations respectively. W E = 2 m = emitter width W = metallurgical base width = 1.2 m = distance between base-emitter junction and base-collector junction (a) Calculate the neutral base width W b for V CB = 0 and V EB = 0.4 V, repeat for V CB = 0 and V EB = 0.6 V. (b) Calculate the base transport factor and the emitter injection efficiency for V EB = 0.4 and 0.6 V. (c) Calculate , , I E , I B and I C for the two values of V EB ....
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This note was uploaded on 02/21/2010 for the course ECE 440 taught by Professor Staff during the Spring '08 term at University of Illinois, Urbana Champaign.

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hw12 - and the amplification factor , assuming the emitter...

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