Consider the bias circuit portion of the 741 op-amp in Figure 13.5. Assume transistor parameters of \(I_{S}=5 \times 10^{-16} \mathrm{~A}\). Neglect base currents.

(a) Redesign the circuit such that \(I_{\mathrm{REF}}=0.5 \mathrm{~mA}\) and \(I_{C 10}=30 \mu \mathrm{A}\) for bias voltages of \(\pm 15 \mathrm{~V}\). What are the values of \(V_{B E 11}, V_{E B 12}\), and \(V_{B E 10}\) ?

(b) Using the resistor values found in part (a) and assuming \(V_{B E}\) (on) \(=V_{E B}\) (on) \(=\) \(0.6 \mathrm{~V}\), determine the values of \(I_{\mathrm{REF}}\) and \(I_{C 10}\).

(c) What are the percent differences in the current values between parts (a) and (b).

Figure 13.5:-

Transcribed Image Text:

Noninverting input Q3 Offset null R = 1 Q8 Inverting input Q 300 ww Q6 Rs= 40 IREF 12 Q10 Q11 R = 150 R = R = 15 Offset Input stage null Bias circuit V+ V Figure 13.5 Bias circuit and input stage portion of 741 op-amp circuit