Hardware Reference
In-Depth Information
Concluding Remarks
In this chapter we presented grounded and floating immittance realization
methods and circuits using different varieties of CCs such as DO-CCIIs,
DVCCs, CCIIIs, DXCCIIs, MICCIIs, DDCCs, DO-CCCIIs and FDCCIIs. It
must be recalled that using a single CCII although one can realize a grounded
lossless inductor but it requires as many as five passive elements namely four
resistors and a capacitor with a constraint in terms of a specified relation
between the four resistors to enable the realization of lossless inductor.
By contrast, in this chapter it has been established that using various
modified versions of the CCs only three passive elements along with a single
active element are enough to perform the same function. Although a cancel-
lation condition is still needed in some cases, however, this is compensated by
the advantage of employing a grounded capacitor in several cases. A partic-
ularly novel circuit results when an FDCCII is employed in the arrangement
proposed by Kacar [
41
] in which a lossless inductor results from a single
FDCCII and only three passive elements-
all of which are grounded.
In case of realizing a floating inductor, particularly the lossless one, it was
implied by several authors that if this is needed to be accomplished by only
three passive elements then at least three CCs are needed while if the
realization is to be attained with only two CCs then at least five passive
elements are needed.
4
By contrast, in this chapter, a variety of circuits have been included which
demonstrate that if modified forms of CCs offering increased capability and
more flexibility are employed then there are numerous ways in which floating
impedances of specific kind or those of general nature can be indeed realized
with only two active elements and no more than three passive elements. In
most of such circuits, at least one grounded capacitor is assured however, in
some cases, such as in DVCC- based floating FDNR of Sedef and Acar all the
three passive elements can be grounded.
It is also interesting to note that in mixed-source arrangement such as those
employing DO-CCCII and OTA the only grounded element used is grounded
capacitor along with the advantage of electronic tunability of the realized
inductance value. On the other hand, to realize electronically-tunable induc-
tors in both grounded and floating forms, the DXCCII appears to be a
particularly interesting element since a MOSFET connecting between its
input terminals X
P
and X
N
results in cancellation of square non-linearity
(continued)
4
It is interesting to note that in view of the equivalence of CCII- and nullor, these conjectures have
their basis in some important theorems existing in literature in the context of gyrator realization
using nullors [
62
].
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