set15new - r e , r , and r ic . Answers: r e = 51 . 3 , r =...

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ECE3050 — Assignment 15 1. The f gure shows a JFET current source used as the tail supply for a di f amp. It is given that V = 15 V , β =0 . 004A / V 2 ,and V TO = 3V .U s et h ee q u a t i o n s I D = β ( V GS V TO ) 2 and V GS = I D R S toso lveforthedra incurrent I D . 2. The f gure shows a BJT current source. It is given that V + =24V , V = 24V , V T =25mV , I S =7 . 5 × 10 15 A ,and β =49 . (Note that β =49 isalowcurrentga in ,butitforcesyouto consider the base current.) (a) Solve for V BE for I C =3mA .An sw e r : V BE =0 . 668V . (b) Solve for R E such that the voltage across R E is V BE .An sw e r : R E = 218 . (c) If I 2 =10 I B ,so lvefor R 2 .An sw e r : R 2 =2 . 18k
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Unformatted text preview: r e , r , and r ic . Answers: r e = 51 . 3 , r = 30 . 8k , r ic = 149k . (f) If the Early e f ect is neglected, i.e. assume that = 0 so that = , solve for R S for I D = 2mA . Note that I Q = I D for the di f amp tail supply. Answer: R S = 1 . 15k . (g) If = 0 . 02V 1 and the voltage at the JFET drain is V D = 1V , solve for the value of (it is greater than ), r , and r id . Note that R Q = r id for the di f amp tail supply. Answers: r = 30 . 9 k , r id = 254k . 1...
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