Hardware Reference
In-Depth Information
C
2
R
1
R
2
R
3
s
2
s
þ
1
C
1
C
2
R
1
R
2
I
out
3
þ
I
out
1
¼
ð
12
:
109a
Þ
I
in
Ds
ðÞ
and a LPF can be realized by adding I
out2
and I
out3
, i.e.
1
C
1
C
2
R
1
R
2
Ds
I
out
3
þ
I
out
2
¼
ð
12
:
109b
Þ
I
in
ðÞ
where D(s) remains same as above.
The
ˉ
0
and Q
0
for all the cases can be given by
r
1
C
1
C
2
R
1
R
2
r
C
2
R
2
R
1
C
1
1
R
3
ω
0
¼
and Q
0
¼
ð
12
:
109c
Þ
Thus,
ˉ
0
and Q
0
can be controlled orthogonally.
12.2.4 Filter Design Using ICCII
The so-called inverting CCII (ICCII) has the same characteristic as a CCII but has
v
x
¼
v
y
. This opens new possibilities for constructing universal CM and VM
biquads as well as mixed-mode biquads using ICCII. In this section, we include
some selected universal biquads configurations using ICCIIs. The departure
v
x
¼
v
y
from the characteristic of normal CCII+ is particularly useful
in
non-linearity cancellation of the v
D
i
D
characteristics of the MOSFET if its drain
and source are connected between Yand X terminals respectively of the ICCII. This
immediately hints to the possibility of constituting a linear, external voltage-
controlled MOSFET-C integrator with a capacitor connected from the Z-terminal
to ground. Thus, interesting MOSFET-C filters could be easily conceived using ICII
and MOSFETs.
ICCII is a five terminal active element and ideally characterized by the following
matrix equations:
2
4
3
5
¼
2
4
3
5
2
4
3
5
I
Y
V
X
I
Z
000
V
Y
I
X
V
Z
100
0
ð
12
:
110
Þ
10
where plus sign indicates ICCII+ and minus sign corresponds to ICCII
respectively.
We now present a number of interesting biquad filter configurations using ICCII
elements.
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