Basic Analog Circuit Building Blocks Using CCs and Application of CCs in Impedance Synthesis - Current Conveyors: Variants, Applications and Hardware Implementations - page 97

floating inductance. Note that whereas the circuit of Fig. 5.18a has the advantage of
employing a grounded capacitor but suffers from the drawback of requiring seven
matched resistances. On the other hand, the circuit of Fig. 5.18b does not require
any passive component-matching but losses the advantage of employing grounded
capacitor(s).
For simulating a floating inductance (FI), five exemplary solutions are shown in
Fig. 5.18c-g . The circuit of Fig. 5.18c requires as many as four op-amps with two
identical GICs and thereby needs perfect matching between them; the circuit of
Fig. 5.18d manages the realization of the floating inductance using only three
op-amps and a grounded capacitor but suffers from the drawback of requiring ten
matched resistors. The circuits of Fig. 5.18e and f each require only two op-amps
but realize lossy floating inductor (series-RL type and parallel-RL type respec-
tively) but suffer from the drawback of requiring more than one capacitor as well as
matching between several components. Lastly, the circuit of Fig. 5.18g realizes a
lossless floating inductance employing only a single capacitor but still requires a
number of conditions in terms of various resistances to be fulfilled to enable the
required realization.
From the exhaustive literature survey of op-amp based inductance simulation
circuits, it has been well established that using op-amps no circuit exists which can
realize a lossless grounded inductor using a bare minimum number of passive
components (namely only two resistors and a grounded capacitor) and that using
op-amps, it is impossible to simulate a floating impedance of any kind (lossy or
lossless) without requiring any passive component-matching.
In the following sub-section, we will show that using CCs it is possible to devise
synthetic impedance networks which can overcome both the difficulties mentioned
above.

5.3.1 CCII-Based Lossless Grounded Inductance Simulation
Circuits

Sedra and Smith (see reference [3] of Chap. 1 ) while introducing the second
generation current conveyor had outlined a number of basic applications of CCII

including the interesting application of CCII in realizing PII/gyrator. It was shown
that a gyrator can be made from a parallel back-to-back connection of two voltage
controlled current sources of opposite polarity, each realizable from a single CCII+
or single CCII with X-port terminated into a grounded resistor or a grounded

impedance. With port 2 of such a circuit terminated into third impedance (as in
Fig. 5.19a ) the input impedance of the circuit is given by:

Z 1 Z 2
Z 3

Z in ¼ ð 5 : 26 Þ