Hardware Reference
In-Depth Information
Fig. 6.15 VM universal
filter using two CCII+
proposed by Chang and
Tu [
13
]
CCII+
x
+
z
V
3
y
-
R
2
C
1
CCII-
C
1
y
+
z
V
2
x
-
V
0
+
R
1
V
1
-
+
R
3
V
4
-
V
1
þ
V
4
s
2
C
1
C
2
R
1
R
2
R
3
ð
sC
1
R
2
R
3
Þ
V
2
þ
ð
sC
1
R
1
R
3
þ
R
1
Þ
V
3
sC
1
R
1
R
2
V
out
¼
s
2
C
1
C
2
R
1
R
2
R
3
þ
sC
1
R
3
R
1
þ
ð
R
2
Þ þ
R
1
ð
6
:
26
Þ
The various filters can be obtained by the appropriate choice(s) of the input
signals as follows: HPF: if V
2
¼
V
3
¼
V
4
¼
0 (grounded) and V
1
¼
V
in
; BPF: if
V
1
¼
V
3
¼
0, V
2
R
3
6
¼
V
4
R
1
and V
in
is either V
2
or V
4
; LPF: if V
1
¼
0, (V
2
/R
1
+V
3
/
R
2
)
¼
V
4
/R
3
and V
in
¼
V
3
; Notch: if (V
2
/R
1
+V
3
/R
2
)
¼
V
4
/R
3,
and V
in
¼
V
1
¼
V
3
;
APF: if {V
2
/R
1
+V
3
(2/R
2
+ 1/R
1
)}
V
3
.
The experimental verification of the operation of this circuit in various modes
has been successfully demonstrated by building the circuit with R
1
¼
¼
V
4
/R
3
and V
in
¼
V
1
¼
R
2
¼
4K
ʩ
,
R
3
¼
1K
ʩ
C
1
¼
250 pf, C
2
¼
25 nF and CCII+ s implemented with AD844.
Liu and Lee Universal Biquads Three VM universal filter configurations using
two CCIIs, three resistors and two capacitors were presented by Liu and Lee [
14
]
and are shown in Fig.
6.16a-c
.
By a routine circuit analysis (assuming ideal CCIIs), the output voltage of the
circuits of Fig.
6.16a, b
is given by:
V
in
1
s
2
C
1
C
2
R
2
R
3
ð
sC
2
R
3
Þ
V
in
2
þ
V
in
3
R
1
V
1
¼
ð
6
:
27
Þ
C
2
R
2
R
3
s
2
C
1
C
2
R
2
R
3
þ
s
þ
1
The various filter responses can be realized as follows: (i) LPF: if V
in1
¼
V
in2
¼
0
(grounded) and V
in
¼
V
in3
(ii) BPF: if V
in1
¼
V
in3
¼
0 and V
in
¼
V
in2
(iii) HPF: if
V
in2
¼
V
in3
¼
0 and V
in
¼
V
in1
and BPF can also be obtained with V
2
/V
in1
(iv) Notch: if V
in2
¼
0, V
in1
¼
V
in3
¼
V
in
and (v) APF: if V
in1
¼
V
in2
¼
V
in3
¼
V
in
and R
1
¼
R
2
Search WWH ::
Custom Search