Recent Advances and Future Directions of Research - Current Conveyors: Variants, Applications and Hardware Implementations - page 527

16.6 Newer Varieties of Current Conveyors of More
Recent Origin
Although, more than two dozen varieties of CCs have been advanced so far, an
account of which was given in Chap. 10 of this monograph, a number of new
varieties of CCs have been proposed even while this monograph was under prep-
aration. Two examples of the new varieties of CCs which have been introduced
very recently are the voltage summing CC and Z-copy controlled-gain voltage
differencing CC [ 28 , 29 ]. Therefore, it appears that the search for newer varieties
of CCs is still on!
Concluding Remarks
In this chapter, we have outlined some of the ideas related to the hardware
implementation and applications of Current Conveyors which are being
investigated in recent literature and which appear to offer enough scope for
further research. It is hoped that interested readers, with the help of exhaus-
tive list of references [ 1 - 27 , 30 - 50 ] given at the end of this chapter will find
enough ideas for further work and investigations.
16.7 Epilogue
This monograph has presented, in a comprehensive manner, the significant works
done on CCs, their variants, their numerous applications (spread over a thousand
journal papers and conference publications) and their hardware implementations.
It may, however, be noted that in spite a very rich repertoire of circuits
employing CCs available in the literature and documented in this monograph,
although the CCs have received vide acceptability by the academicians, it appears
that the practicing engineers and circuit designers are still hesitant to use CCs and
current mode circuits in their designs. The only exception appears to be the AD844
Current feedback operational amplifier, which even though is internally composed
of a translinear CCII + followed by a translinear voltage follower.
Another very curious phenomenon to be observed is that there are a number of
commercially available ICs which are labelled as high-frequency and/or high-slew
-rate op-amps or OTAs, but inside their architecture lies essentially a CC-hardware.
Notable examples in this category are AD844, OPA 660, OPA860 and OPA 2662
all of which have translinear CCs inside. Thus, it is ironical that the professional
engineers and designers have no hesitation in using current-mode techniques and
current conveyors inside the chips but are still hesitant in trying current-mode
application circuits employing the very same building blocks explicitly.
It is hoped that this monograph, which contains more than 500 CC-based
circuits, the performance of some of which has been experimentally verified by
their proposers using commercially available devices (such as AD844/LF356 along