Most commercial op-amps are designed to be unity-gain stable [26]. That is, they are stable when used in a unity-gain configuration. To achieve higher bandwidth, some op-amps relax the requirement to be unity-gain stable. One such amplifier has a DC gain of 105 and a bandwidth of 10 kHz. The amplifier, G(s), is connected in the feedback circuit shown in Figure DP7.8(a).The amplifier is represented by the model shown in Figure DP7.8(b) where Ka = 105 . Sketch the root locus of the system for K. Determine the minimum value of the DC gain of the closed-loop amplifier for stability. Select a DC gain and the resistors R1 andR2.
