Basic Analog Circuit Building Blocks Using CCs and Application of CCs in Impedance Synthesis - Current Conveyors: Variants, Applications and Hardware Implementations - page 106

5.3.5 Floating Generalized Impedance Converters/Inverters
(GIC/GII)

Floating GIC/GII constitute a more general class of active elements which are
useful for creating a variety of floating impedances and a number of CC-based
configurations to realize them have so far been known, for instance, see [ 35 , 43 , 52 ,
87 , 104 , 108 , 113 ].
Higashimura and Fukui [ 52 ] presented a number of circuits for floating immit-
tance simulation using as many as four CCs and as many as four admittances out of
which two were required to be identical.
Their circuits are shown here in Fig. 5.27a-c . All the circuits realize a floating
admittance given by:

Y 1 Y 3
Y 2

Y in ¼ ð : Þ

5 35

By the judicious choice of the components (resistive/capacitive), the circuits can be
used to realize either lossless FIs or lossless FDNR but the drawback of requiring
two matched admittances might be a deterrent in many practical applications.
Another circuit, which although employs four CCs but has the advantage of
employing all CCII+ only, was proposed by Yuce et al. [ 113 ] and is shown in
Fig. 5.28 . This circuit is characterized by

1

y 1 y 2 y 1 y 2

y 4

1 1 1

½ ¼ Y

y 3 þ

¼ Y eq ð 5 : 36 Þ

11 11

Although the circuit realization does not depend upon matching of component
values but two capacitors would be needed to simulate a lossless FI although both
the capacitors can be grounded. On the other hand, in the case of floating FDNR
simulation, the two capacitors employed will be both floating.
A practical advantage of this circuit is that it is readily implementable using
AD844 due to the employment of only CCII+ s.
Another four-CC-based generalized floating impedance convertor was advanced
by Toumazou and Lidgey [ 43 ] which is based upon an appropriate connection of
two differential voltage controlled current sources (Fig. 5.29 ).
By straight forward analysis, it can be easily verified that the floating impedance
realized by this circuit is characterized by:

V 1 V 2 Z 1 Z 4

Z 2 þ

i 1 ¼ i 2 ¼

, Z eq ¼

ð : Þ

5 37

Z eq ð Z 3 Þ

Yet another four-CC-based circuit which does not require two matched impedances
like the circuits of Higashimura and Fukui [ 52 ] and does not need four impedances
like the circuit of Yuce et al. [ 113 ] as well as the circuit of Toumazou and Lidgey
[ 43 ], is shown in Fig. 5.30 and was proposed by Senani in [ 35 ].