Feedback_measurement

Published:2009/7/24 20:36:00 Author:Jessie | From:SeekIC

Because op-amp circuits usually include feedback, it is sometimes necessary to measure feedback voltage at a given frequency with given operating conditions.The basic feedback-measurement connections are shown in Fig. 10-A. Although it is possible to measure the feedback voltage, as shown in Fig. 10-Aa, a more accurate measurement is made when the feedback lead is terminated in the normal operating impedance(Fig.10-Ba).If an input resistance is used In thecircuit,and this resistance is considerably lower than the IC inputimpedance,usethe resistance value.If In doubt, measure the input impedance of the IC(asdescribed In chapter 1). Then,terminate the feedback lead In that value(tomeasure open-loop feedback voltage). Remember that open-loop voltage gammust be substantially higher than the closed－loop voltage gam for most Op-ampcircuits to perform properly.



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