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Unformatted text preview: ECE3050 Homework Set 8 1. The f gure shows the ac signal circuit of a cascade common-emitter ampli f er. For each BJT, it is given that I E = 1 . 5mA , = 0 . 99 , = 99 , r x = 20 , r = , and V T = 0 . 025V . The circuit element values are R S = 1k , R E 1 = R E 2 = 47 , R C 1 = R C 2 = 10k . (a) Looking out of the base of Q 2 , use the Norton collector circuit of Q 1 to show that v tb 2 = i c 1 R c 1 = 134 . 03 v s R tb 2 = R C 1 = 10k (b) Use the Norton collector circuit for Q 2 to show that v o = 8097 v s r out = R C 2 = 10k (c) Show that r in = r ib 1 = 6 . 387k (d) If a resistor R L = 1k is connected from output to ground, show that the new gain is reduced by a factor R L / ( r out + R L ) to the value v o /v s = 736 . 1 and that the dB decrease in gain is 20 . 83dB . 2. The ac signal circuit of a common-base ampli f er driving a common-collector ampli f er is shown. For each BJT, it is given that I E = 1 . 5mA , = 0 . 99 , = 99...
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This note was uploaded on 05/25/2011 for the course ECE 3050 taught by Professor Hollis during the Summer '08 term at Georgia Institute of Technology.
- Summer '08