Solution to problem 1 :

 

To determine IRBL, IRBE and VBB for the MECL - II circuit :

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

= [ 0 - 2 x (0.75) - ( - 5.2 ) ] / (2.63 + 0.33)

= 1.25 mA

VBB = [ VCC - IRBL x RBH - VBE(ECL) ]

= [ 0 - 1.25 x 0.33 - 0.75 ]

= - 1.1625 V

IRBE = [VBB - VEE ] / RBE

= [ - 1.1625 - ( -5.2) ] / 2

= 2.01875 mA