Solution to problem 3:

To determine the critical voltage parameters :

IRBL = [ VCC - 2 ( VD(ON)) - VEE ] / ( RBH + RBE )

= [ 0 - 1.5 + 5.2 ] / 2.61 k = 1.418 mA

VBB = 0 - IRBL x RBH - VBE(ECL)

= 0 - 1.418 x 0.3 - 0.75 = -1.175V

VIL = VBB - 0.05V = -1.175 - 0.05 = -1.225V

VIH = VBB + 0.05V = -1.175 + 0.05 = -1.125V

VOH = - 0.75V

IRE = [ VOH - VBE(ECL) - VEE ] / RE

= [ -1.125 - 0.75 + 5.2 ] / 1.54

= 2.16 mA

VOL = VCC - IRE x RCI - VBE (ECL)

= 0 - 2.16 x 0.27 - 0.75

= - 1.333V

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

= { 0.6 + [ 0.27( 0.8 - 5.2 )/ 1.54] }/ (1 + 0.27/1.54 ) = - 0.146V