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a
b
NO
1
NU
1
1
1
NU
1
NO
1
NO
2
Z
L
Z
L
NU
2
2
2
NU
2
NO
2
Fig. 5.14 Floating INIC and VNIC circuits using nullors
a
b
CCII−
CCII−
y
z
y
z
x
x
Fig. 5.15 The equivalence between a CCII- and three-terminal-floating-nullor
later Senani
1
in [
56
] and Higashimura and Fukui in [
52
]
explicitly
employed the
equivalence in the analysis and synthesis of CCII-based circuits.
From the floating negative impedance structures of Fig.
5.14
and the
CCII
: nullor
'
'
CCII
:
'
nullor
equivalence of Fig.
5.15
, it, therefore, appears that four different floating
negative impedance circuits should be possible to be evolved as follows: (i) from
the nullor model of Fig.
5.14a
, the first two-CCII
'
based circuit follows by
combining nullator-norator pair NU
1
-NO
1
to form the first CCII
and combining
NU
2
-NO
2
to form the second CCII
(ii) an alternative circuit is then made by
grouping NU
1
-NO
2
to form the first CCII
and combining Nu
2
-NO
1
to form the
second CCII
. In a similar way, two other floating negative impedance structures,
each using two CCII-s, can also be conceived from the nullor model of Fig.
5.14b
by proceeding exactly in the same way as outlined in steps (i) and (ii) above. A
close examination, however, reveals that, in this set of four circuits, the last two turn
out to be exactly same as the first two! Thus, only two distinctly different circuits
emerge from the above procedure and these are shown in Fig.
5.16
. The circuit of
Fig.
6.16
has been described by Paul et al. in [
38
].
1
The first author (RS) cannot resist commenting that the facts that a composite connection of two
CCs can be used to realize a fully floating four-terminal-floating-nullor (FTFN) and that FTFNs
make it possible to convert an op-amp-based grounded impedance network into a floating
impedance simulation network systematically were
first proposed explicitly
in references [
145
]
and [
146
]. Both of these ideas, now looking backwards in time, might appear simple and obvious,
but were not well-understood or well-recognized in the open technical literature till then.
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