In Fig. P4.90 both the differential pair and the active load have been cascoded to raise the output resistance Ro and, hence, the unloaded gain adm. Specifi cally, the EC pair Q1-Q2 is cascoded by the...

In Fig. P4.90 both the differential pair and the active load have been cascoded to raise the output resistance Ro and, hence, the unloaded gain adm. Specifi cally, the EC pair Q1-Q2 is cascoded by the CB pair Q5-Q6, and the mirror pair Q3-Q4 is cascoded by the CB pair Q7-Q8. (The function of the 1.4-V source, whose details have been omitted for simplicity, is to bias the Q5-Q6 pair so as to keep Q1 and Q2 in the active region over the entire commonmode input range.) (a) Obtain an expression for adm in terms of the betas and the Early voltages of the BJTs (assume r5 ` for simplicity). Hence, show that if all BJTs have the same beta and Early voltage, then gain simplifi es as adm 5 0y3) 3 (VAyVT). (b) Calculate Ro and adm if IEE 5 1.0 mA, 0n 5 30p 5 150, and VAn 5 (4y3)VAp 5 100 V. (c) Estimate the systematic input offset voltage due to non-infi nite 0p). (d) If VCC 5 10 V, VBEn 5 VEBp 5 0.7 V, and VCEn(EOS) 5 VECp(EOS) 5 0.3 V, what is the permissible output voltage range?