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I
ABC
I
ABC1
I
ABC2
I
ABCn
I
n
x
z
1
x
x
z
1
x
z
1
z
1
R
1
R
2
R
n
z
2
z
2
y
z
2
z
2
y
y
y
C
2
C
1
C
n
I
out
i
0
i
2
i
n
i
1
y
z
1
y
z
1
z
1
y
I
input
r
1
r
n
r
2
z
2
z
2
z
2
x
x
x
i
n
i
1
i
2
I
ABC1
I
ABC2
I
ABCn
Fig. 12.42 Realization of the nth-order CM transfer function proposed by Abuelma
'
atti and
Tasadduq [
119
]
12.2.9 Filter Design Using CFCCII
It has been conceptualized by some authors that if an additional current follower is
included in the CCII+ thereby making it a current follower CCII (CFCCII) then
such a modification becomes not only an useful artifice for synthesizing CM higher
order filters but can also lead to interesting CM universal biquads . A plus-type
current follower second generation CC (CFCCII
p
) is characterized by the following
hybrid matrix:
2
3
2
3
2
3
I
y
V
x
I
z
I
0
0000
1000
0100
0100
V
y
I
x
V
z
V
0
4
5
¼
4
5
4
5
ð
12
:
148
Þ
Figure
12.42
shows a translinear CFCCII
p
-based realization of nth-order current
transfer function using only grounded capacitors. The presented circuit configura-
tion is capable of supporting (n + 2) high impedance output currents simultaneously.
By appropriate connection of output currents, the circuit has the ability of
supporting a wide range of current transfer functions.
Abuelma
'
atti-Tasadduq nth order transfer function realization using
CFCCII The method can be explained by considering a general form of nth
order transfer function as:
a
2
s
2
a
n
1
s
n
1
a
n
s
n
I
out
I
input
¼
a
0
þ
a
1
s
þ
þ :::: þ
þ
ð
12
:
149
Þ
b
0
þ
b
1
s
þ
b
2
s
2
þ :::: þ
b
n
1
s
n
1
þ
b
n
s
n
As per the methodology of [
119
], the active realization of this function is shown
in Fig.
12.42
.
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