Realization of voltage-controlled impedances

K.W. Nay and A. Budak (1983) presented a technique employing JFETs and op-amps for obtaining voltage-controlled positive/negative resistance exhibiting wide dynamic range and low distortion. Here two new op-amp-JFET configurations are proposed, which not only realize voltage-controlled resistances but, unlike the Nay configuration, make it possible to realize voltage-controlled inductance and voltage-controlled capacitance elements, too. Experimental results are given to demonstrate the practical validity of the theoretical formulations.<
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