Hardware Reference
In-Depth Information
CCII+
y
R
3
z
x
R
/
CCII+
V
in
y
R
2
z
x
CCII+
CCII+
y
y
CCII+
z
z
x
y
CCII+
CCII+
C
1
x
z
y
y
x
z
C
2
z
x
R
/
R
5
x
R
4
R
1
/
R
1
R
/
V
0
Fig. 6.8 VM universal active filter proposed by Higashimura and Fukui [
8
]
s
2
C
1
C
2
R
4
R
5
=
V
2
V
1
¼
R
3
sC
1
R
4
=
R
2
þ
1
=
R
1
ð
:
Þ
6
13
R
0
3
R
0
2
þ
R
0
1
s
2
C
1
C
2
R
4
R
5
=
sC
1
R
4
=
1
=
The conditions required to realize various filters are found to be LPF:
R
3
¼
R
2
¼
1
,
, and APF:
R
3
/
R
0
3
¼
BPF:
R
1
¼
R
3
¼
1
, HPF:
R
1
¼
R
2
¼
1
, Notch:
R
2
¼
1
R
2
/
R
0
2
¼
R
1
/
R
0
2
.
As compared to its predecessor of the circuit by Toumazou and Lidgey [
7
], the
important advantage of this circuit is that it does not require the type of CCII to be
changed (hence change in topology) to realize the AP function. It has been
demonstrated in [
8
] that using supply current sensing based CCII+ realized with
LF356 op-amps and current mirrors constructed from 25A945 and 25C733 bipolar
transistors, the circuit can realize various filters with
f
0
of the order of 10 KHz
(restricted only due to the bandwidth of the op-amps employed).
6.2.3.2 Single-Input-Multiple-Output (SIMO)-Type Voltage Mode
(VM) Biquads
One of the common categories for VM biquads has been undoubtedly the so-called
SIMO-type biquads which have been in vogue since the times of op-amp-based
biquads such as the well-known Kerwin-Huelsman-Newcomb (KHN) biquad [
167
],
Tow-Thomas biquad [
168
,
169
] Akerberg-Mossberg biquad [
170
], to name a
few. It was, therefore, natural that with the advent of CCs, the possibility of
realizing SIMO-type VM biquads using CCs caught immediate attention of the
researchers, as a consequence, a large number of such biquads are now known, for
instance, see [
9
,
10
-
16
,
17
,
77
,
78
,
83
,
85
,
92
,
94
,
95
,
110
,
118
,
119
,
130
,
131
,
148
,
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