Hardware Reference
In-Depth Information
I
03
I
01
I
in
Z5−
Y
X
Z3−
Z1−
X
I
HP
C
2
DO-CCCII
DO-CCCII
DO-CCCII
I
LP
Z6+
Y
Y
Z2+
X
Z4+
I
BP
(1)
C
1
(3)
I
02
(2)
Fig. 9.32 SIMO type universal biquad filter proposed by Yuce (Adapted from [
29
]
©
2009
Elsevier Ltd.)
Yet another SIMO-type universal CM biquad realizable with only three CCCIIs and
two grounded capacitors was reported by Yuce [
29
] which requires all CCCIIs of
the same kind; all three are DO-CCCIIs. This circuit simultaneously provides the
advantages of electronic-tunability, use of a minimum number of components, lack
of component-matching constraints, low input and high out impedances and requir-
ing the least possible chip area as compared to the various other three-CCCII-based
alternatives due to employment of three identical DO-CCCIIs (Fig.
9.32
).
The
ˉ
0
and Q
0
for all the five responses are given by:
r
1
C
1
C
2
R
x
2
R
x
3
r
C
1
R
x
2
C
2
R
x
3
ˉ
0
¼
Q
0
¼
ð
9
:
45
Þ
;
from where it can be seen that both the parameters can be adjusted arbitrarily; by
simultaneously changing R
x2
and R
x3
while keeping R
x2
/R
x3
constant and vise-
versa. Also, the circuit realizes a non-inverting low pass and inverting band pass, a
non-inverting high pass, a notch filter by adding low pass and high pass output
currents and all pass by adding low pass, band pass and high pass current outputs.
9.10 Mixed-Mode Current-Controlled Multifunction
Filters
Several researchers have ventured into devising circuit configurations which can
operate in dual mode or mixed mode i.e. the same circuit can realize all the five
standard filtering functions in VM as well as in CM. Such mixed-mode circuits have
been proposed using a variety of active elements including current conveyors of the
normal type as well as other recently introduced variety of them. All such mixed-
mode circuits invariably use a relatively larger number of active building blocks
(typically seven or eight of them). Of course, a number of authors have succeeded in
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