Datasheet

C
2
R
2
1
R
1
+ R
4
R
1
V
O2
V
IN
s
2
+ s
1
C
2
R
2
R
5
+ R
6
R
5
R
1
R
1
+ R
4
C
2
C
3
R
2
R
3
1
+
=
s
R
6
R
5
+ R
6
R
1
+ R
4
R
1
R
5
+ R
6
R
6
V
O1
V
IN
s
2
+ s
1
C
2
R
2
R
5
+ R
6
R
5
R
1
R
1
+ R
4
C
2
C
3
R
2
R
3
1
+
=
s
2
R
1
+ R
4
R
1
R
5
+ R
6
R
6
C
2
C
3
R
2
R
3
1
V
O
V
IN
s
2
+ s
1
C
2
R
2
R
5
+ R
6
R
5
R
1
R
1
+ R
4
C
2
C
3
R
2
R
3
1
+
=
V
O
= V
O2
-1
s C
3
R
3
V
O2
= V
O1
-1
s C
2
R
2
V
O1
=
-R
4
R
1
V
0
+
R
5
+ R
6
R
6
R
1
+ R
4
R
1
V
O2
R
5
+ R
6
R
5
R
1
+ R
4
R
1
V
IN
+
V
O1
V
O2
+
-
R
2
A
2
V
O
+
-
C
3
A
3
V
O2
C
2
R
3
LMV771, LMV772, LMV774
SNOSA04F –MAY 2004–REVISED SEPTEMBER 2010 www.ti.com
For A
1
the relationship between input and output is:
(20)
This relationship depends on the output of all the filters. The input-output relationship for A
2
can be expressed
as:
(21)
And finally this relationship for A
3
is as follows:
(22)
Re-arranging these equations, one can find the relationship between V
O
and V
IN
(transfer function of the lowpass
filter), V
O1
and V
IN
(transfer function of the highpass filter), and V
O2
and V
IN
(transfer function of the bandpass
filter) These relationships are as follows:
Lowpass Filter
(23)
Highpass Filter
(24)
Bandpass Filter
(25)
The center frequency and Quality Factor for all of these filters is the same. The values can be calculated in the
following manner:
20 Submit Documentation Feedback Copyright © 2004–2010, Texas Instruments Incorporated
Product Folder Links: LMV771 LMV772 LMV774