L10 Part1 7.3_BJT_1

# L10 Part1 7.3_BJT_1 - α = 1 7 Figure 7.13(5 th ed...

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Lecture 10 Part 1 Monday Feb. 1, 2010 Section 7.3 BJT Differential Pair Zubair Rehman

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2 Figure 7.12 (5 th ed.) The basic BJT differential pair configuration
3 Equivalent Circuit Models: Large-Signal Equivalent Circuit Models: Small-Signal

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4 i C2 = α i E2 Similarly i C1 = α i E1 If V B1 = V B2 = V CM I divides equally between I E1 E2 T B B T B B T B B T B B T E B T E B T E B T E B V V V E V V V E E V V V E E E V V V V V V S V V V S E E V V V S E V V V S E e I i e I i i e i i i I e e I e I i i e I i e I i 1 2 2 1 2 1 2 1 2 1 2 1 1 1 ) / ( ) / ( 1 2 2 2 2 1 2 1 2 1 - - - - - - - - + = + = + = + = = = = = α
5 I I e I i I I e I i V V V E E T B B 05 . 0 73 . 2 1 1 95 . 0 ) 73 . 2 / 1 ( 1 1 3 3 3 2 3 3 1 2 1 = + = + = = + = + = = - - If We see that 4 V T = 100 mV switches which current is on If I I e I i I I e I i V V V E E T B B 27 . 0 73 . 2 1 1 73 . 0 73 . 2 / 1 1 1 1 2 1 1 2 1 = + = + = = + = + = = - - I I e I i I I e I i V V V E E T B B 12 . 0 73 . 2 1 1 88 . 0 ) 73 . 2 / 1 ( 1 1 2 2 2 2 2 2 1 2 1 = + = + = = + = + = = - - If

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6 Figure 7.14 (5 th ed.) Transfer characteristics of the BJT differential pair of Figure 7.12 assuming
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Unformatted text preview: α = 1 7 Figure 7.13 (5 th ed.) Different modes of operation of the differential pair: (a) The differential pair with a common-mode input signal V CM . (b) The differential pair with a “large” differential input signal. (c) The differential pair with a large input signal of polarity opposite to that in (b). The differential pair with a small differential input signal V i ....
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L10 Part1 7.3_BJT_1 - α = 1 7 Figure 7.13(5 th ed...

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