An npn differential pair employs transistors for which vBE =690mVat iC =1 mA, and β =50. The transistors leave the active mode at vCE 0.3 V. The collector resistors RC =82 kΩ, and the power supplies are±1.2 V. The bias current I = 20 μA and is supplied with a simple current source.
(a) For vB1 = vB2 = VCM = 0 V, find VE, VC1, and VC2.
(b) Find the input common-mode range.
(c) If vB2 =0, find the value of vB1 that increases the current in Q1: by 10%.