Hardware Reference
In-Depth Information
2
R
0
I
b
3
V
T
H
OHP
¼
H
OBP
¼
H
OLP
¼
ð
:
Þ
9
38
Because of the ready availability of the three basic transfer functions (i.e. LPF, BPF
and HPF) with correct polarities as well as due to the equal values of all the three
gains, a band stop filter (BSF) function is realizable just by joining LPF and HPF
outputs. On the other hand, an APF is realizable by joining all the three output
terminals. It may be noted that a novel feature of this circuit is that no component-
matching or equality constraint is needed in any of these two additional realizations.
In [
27
], Chen and Chu presented a multiple-input-multiple-output (MIMO)-type
universal filter which, in contrast to the KHN equivalent biquad described above,
needs only three CCCIIs (rather than five, as employed in KHN equivalent circuit).
This circuit is shown in Fig.
9.30
.
Chen and Chu [
27
] have demonstrated two possible modes of operation of this
circuit out of which, the following appears to be interesting because of the reason
that in this case, all the five generic filters function can be realized from the same
circuit without requiring any cancellation-constraints. The five functions realized
by this circuit are given by:
s
C
1
R
x
2
Ds
1
C
1
C
2
R
x
2
R
x
3
Ds
s
2
1
C
1
C
2
R
x
2
R
x
3
Ds
I
in
¼
I
in
¼
þ
I
01
I
02
I
03
I
in
¼
ð
9
:
39
Þ
ðÞ
;
;
ðÞ
ðÞ
I
HP
I
in
¼
I
02
I
in
þ
I
03
I
in
¼
s
2
Ds
ð
9
:
40
Þ
ðÞ
s
2
1
1
C
1
C
2
R
x
2
R
x
3
Ds
C
1
R
x
2
s
þ
I
AP
I
in
¼
I
01
I
in
þ
I
03
I
in
¼
ð
9
:
41
Þ
ðÞ
I
b2
I
b1
I
b3
I
i3
I
i2
Z+
Z−
Z+
Y
Y
Y
V
2
V
1
3
2
1
C
1
C
2
Z+
Z−
I
03
I
01
I
02
Z+
Z−
X
X
X
Z−
V
3
I
i1
Fig. 9.30 MIMO type CM universal filter proposed by Chen and Chu (Adapted from [
27
]
2009
©
IEICE)
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