Hardware Reference
In-Depth Information
a
R
4
CCII−
R
3
x
z
y
R
2
z
CCI−
x
y
x
z
R
1
CCII−
y
x
C
2
CCII+
z
y
I
02
CCI−
I
01
y
x
x
y
z
z
I
in
I
03
CCI−
CCI−
C
1
x
z
y
b
c
I
0
CCII±
CCII±
I
01
y
x
x
y
z
z
+
V
in
I
in
−
r
1
r
2
r
1
Fig. 6.31 CM biquad structure employing CCs proposed by Senani [
25
]
A CM notch filter can be obtained by joining the outputs providing I
04
¼
I
01
+I
03
and APF by adding I
01
,I
02
and I
03
which gives I
05
¼
I
01
+I
02
+I
03
. The respective
transfer functions are given by:
R
1
C
1
s
2
s
1
þ
1
C
1
C
2
R
1
R
2
s
2
þ
1
C
1
C
2
R
1
R
2
Ds
I
04
I
in
¼
I
04
I
in
¼
and
ð
6
:
44
Þ
ðÞ
Ds
ðÞ
provided that R
3
¼
R
4
.
Chang
'
s Universal CM Biquad Figure
6.32
shows a universal CM biquad
presented by Chang [
26
].
This filter configuration employs seven CCIIs, eight grounded resistors and two
grounded capacitors and offers independent control of
ω
0
,Q
0
and current gain
through separate grounded resistors. Assuming ideal CCIIs, the various transfer
functions are given by:
s
2
R
R
8
Ds
R
4
R
7
C
2
Ds
R
1
s
R
1
R
4
R
5
R
8
C
2
C
1
Ds
I
high
I
i
¼
I
band
I
i
¼
I
low
I
i
¼
ðÞ
;
;
ðÞ
ðÞ
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