Basic Analog Circuit Building Blocks Using CCs and Application of CCs in Impedance Synthesis - Current Conveyors: Variants, Applications and Hardware Implementations - page 93

Fig. 5.13 Four floating
negative impedance circuits

a

z z

CCI±

CCI±

y y

x

x

1 Z L

2

b

z z

CCI±

CCI±

x y x

y

1

Z L

2

c

CCII+

CCII+

y y

Z L

z z

x

x

2

1

d

CCII+ CCII+

y y

z Z L z

x

x

2

1

An interesting question which arises is whether two CCII-s can be used to realize
floating negative impedance? The answer to this question is in the affirmative and
two interesting ideas lead to the creation of such circuits.
Firstly, there are two classical nullor-based lattice structures which realize
floating negative impedance. These are shown in Fig. 5.14 . Note that the circuit
of Fig. 5.14a is the current inversion type floating NIC (INIC) while that of
Fig. 5.14b is the voltage inversion type NIC (VNIC). Secondly, if one observes
the terminal equations of a CCII- i.e. i y ¼

i x (see Fig. 5.15a ) and
the terminal equations of a three terminal nullor, it is seen that these are exactly
equivalent to a CCII

0, v x ¼ v y and i z ¼

(see Fig. 5.15b ).
At this point, it must be emphasized that after the introduction of CCs in 1968
and 1970, it was not until 1978 onwards when first De Jager and Smit in [ 144 ] and