The Evolution and the History of Current Conveyors - Current Conveyors: Variants, Applications and Hardware Implementations - page 11

• 2005:In[ 59 ], Gift introduced a new circuit element referred to as an operational
conveyor comprising of an op-amp and a current conveyor. This operational
conveyor was demonstrated to be superior to a current conveyor in a number of
situations.
In the same year, Mahmood et al. [ 76 ] proposed a digitally-controlled current
gain, fully-differential second generation CMOS current conveyor operated
from a low voltage supply of the order of 1.5 V DC.

• 2008:In[ 60 ], Soliman demonstrated that two types of inverting CCII namely,
ICII+ and ICII are universal building blocks.
In the same year, Horng et al. [ 62 ] proposed an interesting variant of CCs
called multi input differential current conveyor (MIDCC). MIDCC is basically
an adjoint of MOCC and is, therefore, useful in deriving a universal voltage-
mode biquad starting from universal current-mode biquad.

• 2009: Hwang et al. [ 63 ] proposed the multiplication mode current conveyor

(MMCC). The internal circuit structure of this was obtained by using a DVCC
and a folded Gilbert cell. MMCC was shown to be useful element for designing
four quadrant multiplier, squarer, summer and analog divider applications.
Siripruchyanun et al. [ 64 ] introduced current controlled current conveyor
transconductance amplifier (CCCCTA) whose parasitic resistance at the current
input port is controllable by an external input bias current. This building block
was shown to be useful for both current mode and voltage mode signal
processing systems. An attractive feature of the CCCCTA is that a single unit
is sufficient to design a variety of functional circuits such as VM and CM
universal biquad or a grounded inductor simulator.
In [ 65 ], Sobhy and Soliman presented balanced output inverting third gener-
ation current conveyors ICCIII . The strength of these blocks was demonstrated

by many applications in the design of integrators, filters and oscillators.
Marcellis et al. [ 66 ] proposed a voltage and current gain second generation
current conveyor which they chose to call VCG-CCII. CMOS architecture was
obtained by replacing voltage and current buffers of the standard CCII by
voltage and current amplifiers with tunable gains to obtain an extremely flexible
and versatile building block.

• 2010: Chunhua et al. [ 67 ] demonstrated that a current controlled fully balanced

second generation current conveyor (CFBCCII) is particularly useful building
block for designing multi loop feedback current-mode balanced filter.

• 2012:In[ 68 ], Metin et al. came up with yet another variant of CCs called

differential current conveyor (DCCII) which has a current difference capability.
A DCCII is characterized by

2
4

3
5 ¼

2
4

3
5

2
4

3
5

v XN
v XP
i Z
i Y

0
0
α P
0

0
0
α N
0

ʲ N
ʲ P
0
0

i XP
i XN
v Y

ð 1 5 Þ

:

where ideally β N ¼ β P ¼ 1 and ʱ N ¼ʱ P ¼ 1 that represent the voltage and current

transfer ratios of the DCCII, respectively.