A new generalized inverter based on the active hybrid

The building block for the new generalized immittance inverter is a 3-port known as the active hybrid network. One of its ports is bidirectional, and matches a design admittance y₀. The second port operates in the send, while the third port operates in the receive direction. The hybrid is constructed from an op-amp and a 5-port network composed of a few resistors and the design admittance y₀. There are two versions of the hybrid: the voltage-inverting (i.h.) and the noninverting hybrid (n.i.h.). The inverter consists of an i.h. and an n.i.h. connected at their unidirectional ports in a loop. The gyration admittances are actual driving-point admittances in the circuit, namely the design admittances y₀, y'₀ of the two hybrids. Such an inverter, when terminated at its output port by a load admittance y, will give at its input port an input admittance y_in = y₀y'₀/y. Expressions are derived for the y parameters of the inverter at higher frequencies, thus accounting for the finite bandwidth of the op-amp. Two special cases are particularly treated, and experimental results are obtained for them. The first is the case of the resistive gyrator, for which y₀ and y'₀ are pure conductances. The second is the case of the capacitive gyrator, for which y₀ and y'₀ are pure capacitive susceptances. The capacitive gyrator is used to produce the supercapacitor, or f.d.n.r., and the results of measurements on a number of f.d.n.r. networks are given.