Hardware Reference
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a
b
R
2
CCII+
R
1
y
R
2
y
z
+
R
3
R
1
+
z
x
CCII+
C
0
V
in
+
R
3
x
+
−
V
0
V
0
V
in
C
0
−
−
−
c
d
y
R
2
z
CCII+
+
x
R
2
y
R
1
R
3
V
in
+
−
R
1
z
R
3
CCII+
+
V
0
x
V
in
+
−
V
0
C
0
−
C
0
−
e
f
R
3
C
0
R
2
R
2
R
3
y
y
CCII+
z
R
1
z
CCII+
x
+
V
in
+
−
V
in
+
−
x
+
R
1
V
0
V
0
C
0
−
−
Fig. 6.3 The grounded-capacitor-based first order all pass filter configurations proposed by
Cicekoglu et al. [
3
]
The voltage ratio transfer function of the circuits given in Fig.
6.3
can be
expressed in the following general form
V
0
s
ðÞ
V
i
s
K
1
sT
ðÞ
¼
ð
6
:
3
Þ
1
þ
sT
By a straight forward analysis, the specific values of the transfer voltage ratio,
gain K, radian frequency
ω
0
and the design constraints for the various circuits are
shown in Table
6.1
.
It is worthwhile to point out that the circuits of Fig.
6.3b-d
have the advantage
that the X-port parasitic input impedance r
x
can be readily absorbed in the external
resistors employed, whereas the circuit of Fig.
6.3f
has the advantage of providing a
voltage output from a low output impedance terminal since the same is being taken
from the X-terminal of the CCII+.
With CCII implemented from AD844, there is flexibility of taking out a
low impedance output in circuits of Fig.
6.3a-e
by exploiting the buffer between
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