The Miller-compensated two-stage op amp in Fig. 9.25 can be modeled as shown in Fig. 9.26. In the model, let g_m1= 0.5 mA/V, R₁= 200 kΩ, g_m6= 2 mA/V, R₂= 100 kΩ, C₁= 0.1 pF, and C₂= 8 pF.

(a) Assume the op amp is connected in negative feedback with f = 0.5. What is the value of C that gives a 45° phase margin? Assume the right half-plane (RHP) zero has been eliminated, and assume the feedback network does not load the op amp.

(b) What value of R_z in Fig. 9.26 eliminates the RHP zero?

Fig. 9.25:

Fig. 9.26:

Transcribed Image Text:

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