Question

1) Consider the circuit in Fig. 1 (a). Assume that the transistor is operating in the linear region and has β 100 R-90 KD R-10 -17V 10 ka R,-10 KD (a) Problem (b) After Thevenin Equivalent Fig I. Circuits for Problem1) a) (8 points) Find the Thevenin equivalent across a - b. Indicate the values of Vih and Res in Fig. 1(b). b) (6 points) Determine io, fe and ie e) (I point) Determine Vor and verify that the assumption that the transistor is in linear region is correct.

Answer 1

beta = 100 assume transistor is in linear region apply thevinin equivalent at v_th = v_cc R_L/(R_1 + R_2) = 17 times (10 k)/(90 k + 10 k) = 1.7 v R_in = R_1/R_2 = 90 k/ 10 k = 9 k ohm Apply k v l to input loop - v_f_n + R_ln i_b + v_Be + i_e R_epsilon = 0 - 1/7 + 9 times 10^3 i_b + 0.7 + (1 + 100) i_b times 10^3 = 0 (10 times 10^3 i-b = 1 []therefore i_e = (1 + beta) i_b] i_b = 0.901 mu A i_c = beta i_b = 100 times 9.091 times 10^-6 = 0.909 m A i_e = (1 + beta) i_b = 101 times 9.091 times 106^-6 = 0.918 m A apply k vl to output loop 17 = 10 k i_c + v_CE + i_2 91 k) = v_CE = 17 - 10 times 1063 (0.909 times 10^-3) - 10^3 (0.918 times 10^-3) v_CE = 4.922 active region