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Step 1 of 5 11.093P Consider the circuit shown in Figure 1. -K -K Figure 1 Step of 5 For a feedback amplifier for which the open-loop transfer function of single stage 4(f) is, Feedback amplifier for which the open-loop transfer function A(f) is, = -K -K' = Step 3 of 5 Consider the feedback factor, B as The loop gain is. AB Step of 5 The phase of the loop gain is, = tan Find the frequency at which the phase margin is equal to 180° tan tan 60° Thus, the frequency of oscillation is Step of 5 At this frequency the loop gain magnitude is unity. =1 Substitute Hz for Thus, the minimum value of K at which the circuit oscillates is 1.65