ABSTRACT
The ideal active elements are devices having one to three ports with properties that make them very useful in network synthesis. The most important ideal active elements in network synthesis fall into the following groups: ideal controlled sources; generalized impedance converters; generalized impedance inverters; negative resistance; and current conveyors. This chapter provides practical realizations using two active devices which are commercially available, namely, the operational amplifier (opamp) and the operational transconductance amplifier (OTA). The opamp and OTA are special cases of two ideal active elements, and their implementations in Integrated Circuit form make them indispensable, both in discrete and fully integrated analog network design. Although the transistor, either the bipolar or the unipolar, is essentially the basic active element in the realization of all other active elements in practice. The active elements will be employed in the design of active filters.
