Solution to Problem 1

( i ) To determine VBB:

VBB = VCC - 2(VD(ON)) / R1 = 5 - 2(0.75)/1 = 1.5V

(ii) Critical voltages :

VOH = 5V

VIL = VBB - 0.05 = 1.5 - 0.05 = 1.45V

VIH = VBB + 0.05 = 1.5 + 0.05 = 1.55V

VOL = VCC - RC( VIH - VBE(ECL) + VEE)/RE

= 5 - 1.5( 1.55 - 0.75 + 0)/2

= 4.4V

VS = [VCC + VBC(SAT) + RC{VBE(SAT) - VEE}/RE]/( 1 + RC/RE)

= [ 5 + 0.6 + 1.5(0.8 - 0)/2]/(1 +1.5/2) = 3.54V