Hardware Reference
In-Depth Information
Table 6.1 The various Transfer functions and the realizability conditions for the circuits of
Fig.
6.3
Transfer function
K
ω
¼1/T
Design constraints
0
R
1
C
0
1
R
1
C
0
s
1
R
1
C
0
þs
1
R
2
¼2
R
3
1
s
1
R
2
¼2
R
3
R
2
1
R
1
C
0
2
R
2
C
0
1
R
1
C
0
2
R
2
C
0
þs
>
2
R
1
1
R
1
C
0
2
R
2
C
0
s
1
R
2
¼
2(
R
3
+
R
1
)
1
R
3
C
0
þ
1
R
1
C
0
1
R
3
C
0
þ
1
R
1
C
0
þs
1
R
3
C
0
þ
1
R
1
C
0
1
R
1
C
0
s
2
R
2
1
R
1
C
0
R
2
R
1
R
3
¼
R
2
R
1
1
R
1
1
R
2
2
R
1
C
0
þs
R
2
>
R
1
2
R
1
1
s
1
R
3
¼
R
1
R
2
>R
1
1
R
1
C
0
1
R
2
C
0
1
R
1
C
0
1
R
2
C
0
þs
1
R
1
C
0
1
R
2
C
0
s
1
R
1
¼2
R
3
R
1
1
R
2
C
0
2
R
1
C
0
1
R
2
C
0
2
R
1
C
0
þs
>
2
R
2
1
R
2
C
0
2
R
1
C
0
the Z- terminal of the CCII+ and the voltage output terminal-W of AD844. With
AD844 employed to realize the CCII+, the circuits are found to operate well up to a
frequency in the MHz range.
Another circuit, which uses a CCII
and also employs only two equal-valued
resistors and a single capacitor, was advanced by Khan and Maheshwari [
4
] and is
shown in Fig.
6.4
the transfer function of this circuit is given by (for R
1
¼
R
2
¼
R)
V
out
V
in
¼
sCR
1
1
with R
1
¼
R
2
¼
R
ð
6
:
4
Þ
sCR
þ
6.2.2 Single-CC Biquads
A four or five passive elements-based configuration employing two different types
of CCIIs was proposed by Chong and Smith in [
5
] which can realize BPF, LPF and
HPF filter responses by appropriate choice(s) of the type of CCIIs and passive
elements. The first circuit configuration as shown in Fig.
6.5a
employs a CC
A
(CCII
which is characterized by i
y
¼
0, v
x
¼
v
y
and i
z
¼
i
x
,) and can realize a
BPF response whose transfer function is given by
V
0
V
in
¼
sC
2
R
4
ks
2
C
1
C
2
R
3
R
4
þ
ð
:
Þ
6
5
½
sR
4
C
1
þ
ð
C
2
Þ þ
1
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