Basic Analog Circuit Building Blocks Using CCs and Application of CCs in Impedance Synthesis - Current Conveyors: Variants, Applications and Hardware Implementations - page 117

a

Y 2

I 1 Y 1

Y 3 I 2

V 1

V 2

Y 3

b

Y 1

CCII

CCII

Y 2

CCII

x
y

x
y

y

+ z

1

+

z

z

+

2

x

c

Y 3

CCII

CCII CCII

Y 2

x
y

1

x
y

2

x
y

+ z

+

+ z z

Y 1

Fig. 5.41 CC based floating impedance realization derived from a nullor models proposed by
Higashimura and Fukui [ 53 ](a) Nullor model of FI (b), (c) CCII based FIs derived from the
nullor model

OTAs to achieve properties which are not feasible with circuits containing only
CCs. Two such examples are outlined in the following.
In the circuit of Fig. 5.43 , Maundy et al. [ 122 ] have presented a mixed source
arrangement for realizing a floating inductance using two CCs and two op-amps. In
their proposition, the two CCs along with a resistor have been employed to create a
differential voltage controlled current source. By standard analysis, it can be easily
found out that between ports 1 and 2, the circuit realizes a floating impedance of
value Z 1-2 ¼ sC 1 R 1 R 2 .

In the second case proposed by Higashimura and Fukui [ 62 ], (Fig. 5.44 ), an OTA
is used in conjunction with two CCs, a resistor and a grounded capacitor, to create
an inductance which is electronically tunable through the external bias current of
the OTA. By straight forward analysis, it has been found that to realize a floating
inductance of value L eq ¼ CR 1 /G m since for bipolar OTA, such as CA3080, its

transconductance G m is given by G m ¼

I bias /2V T. It is, thus, clear that simulated
inductance value is linearly controllable through the external bias current I bias .