Basic Analog Circuit Building Blocks Using CCs and Application of CCs in Impedance Synthesis - Current Conveyors: Variants, Applications and Hardware Implementations - page 100

Fig. 5.20 Active gyrator
proposed by Soliman [ 9 ]
(Also by Paul et al. [ 33 ])

R 1

CCII

y

C

+

z

R 2

Z in x

R 3

R 4

It is, thus, clear that with Z 3 as a capacitor C 0 and the remaining impedances being
resistors R 1 and R 2, the input impedance would be purely inductive with equivalent
simulated inductance being given by L eq ¼

C 0 R 1 R 2 . An alternative circuit which
realizes exactly the same type of input impedance while using all the three
grounded components only is shown in Fig. 5.19b . This alternative form of the
active gyrator was recently studied by Cicekoglu [ 89 ] considering the voltage and
current tracking errors of the CCIIs. It has been found that this alternative version
does offer better performance than the Sedra-Smith gyrator of Fig. 5.19a . Several
other forms of lossless grounded inductors using current conveyors have been
advanced from time to time such as [ 24 , 34 , 93 , 105 , 106 ], however, these
invariable require more than two CCs.
It is worth pointing out that grounded ideal FDNRs can be realized from either of
the circuits of Fig. 5.19 by choosing Z 1 and Z 2 as capacitors and Z 3 as a resistor.
Furthermore, if both the CCII are taken as CCII+, then a frequency dependent
positive resistance (FDPR: an element having Z(s) 1/Ds 2 ) is realizable as in [ 18 ].

Lastly, it may be pointed out that instead of one CCI+ and one CCII

¼

,an
entirely CCII + based circuit (thereby employing three CCII+ s) can be easily
obtained by realizing a CCII by two CCII+ s. In addition, there are a number of

other ways of deriving such three CCII+ based lossless GI circuits from those of
Fig. 5.19 as elaborated in [ 102 ].

5.3.2 Active Gyrator Using a Single CCII

The active gyrators using CCs have been proposed by many authors [ 63 , 65 , 69 , 70 ,
85 , 114 , 116 , 121 , 122 , 125 , 128 , 129 ], however, the first circuit to realize an active
gyrator and thereby a lossless inductance was proposed by Soliman in [ 9 ] (and also
independently by Paul-Dey-Patranabis in [ 33 ]) and is shown in Fig. 5.20 .