Some second-source manufacturers of the 741 op amp use the alternative circuit of P5.12 to establish the voltage drop VBB needed to bias the push-pull pair. The circuit is called VBE multiplier...

Some second-source manufacturers of the 741 op amp use the alternative circuit of P5.12 to establish the voltage drop VBB needed to bias the push-pull pair. The circuit is called VBE multiplier because VBB can be adjusted to any (not necessarily integer) multiple of VBE by suitable choice of the R1yR2 ratio. (a) Assuming Is1 5 Is2 5 4Is3 5 8 fA and Q3 draws negligible base current, specify suitable values for R1 and R2 to achieve VBB 5 1242 mV as in Example 5.1, under the constraint that the 176-A current split equally between R1 and Q3’s collector. What is the quiescent current IQ of the Q1-Q2 pair? (b) Assuming Is4 5 Is3, fi nd vI (in millivolts) for vO 5 0. (c) Find vO (in millivolts) if vI 5 0 and RL 5 `. (d) Repeat (c), but with RL 5 1 kV.