09W-quiz-2-sol

# 09W-quiz-2-sol - ECE65(Winter 2009 Midterm 2 Name Notes 1...

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ECE65 (Winter 2009), Midterm 2 Name: Notes: 1. Write your answers on these three sheets. 2. For each problem, 20% of points are alloacted for the correct ±nal answer. Problem 1. Find the state of this transistor if v GS > v t . (5pts) By KVL: v DS = v GS . Since v GS > v t , the NMOS is ON (should be either in active or ohmic). Furthermore, since v DS = v GS > v GS - v t , NMOS should be in active region.

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Problem 2. In the circuit below with Si diodes, fnd i For - 20 v s 20 V (13pts) S V - + i i S i D 5k 5k D1 D2 KCL: i D 1 = i D 2 = i D KCL: i s = i D + i KVL: v s = 5 × 10 3 i s + v D 1 + v D 2 KVL: v D 1 + v D 2 = 5 × 10 3 i Because the two didoes are in series, i D 1 = i D 2 = i D , the two diodes are either ON ( i D > = 0) or O±± ( i D = 0). ±or BOTH diodes being ON: v D 1 = v D 2 = v γ = 0 . 7 V, i D > 0. Substituting in the circuit equations we get: v s = 5 × 10 3 i s + v D 1 + v D 2 v s = 5 × 10 3 i s + 1 . 4 i s = 2 × 10 - 4 ( v s - 1 . 4) v D 1 + v D 2 = 5 × 10
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## This note was uploaded on 05/26/2010 for the course ECE 65 taught by Professor Coles during the Spring '08 term at UCSD.

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09W-quiz-2-sol - ECE65(Winter 2009 Midterm 2 Name Notes 1...

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