LM258, LM358, LM358A, LM2904, LM2904A, LM2904V, NCV2904, NCV2904V
V
CC
R3
C
C
R1
V
in
-
1/2
V
O
LM358
+
CO
CO = 10 C
R2
V
ref
1
2
V
ref
=
V
CC
Given:
f = center frequency
o
A(f ) = gain at center frequency
o
Choose value f , C
o
Q
ꢄ f C
Then: R3 =
R1 =
1
2
Triangle Wave
Output
V
=
V
CC
R2
ref
o
R3
300 k
V
+
1/2
ref
2 A(f )
o
R3
+
1/2
R1 R3
2
LM358
-
75 k
R2 =
4Q R1 -R3
LM358
-
R1
100 k
Square
Wave
Output
Q f
o
o
For less than 10% error from operational amplifier.
Where f and BW are expressed in Hz.
< 0.1
V
ref
BW
C
o
R
f
R1 + R
R2 R1
C
If source impedance varies, filter may be preceded with voltage
follower buffer to stabilize filter parameters.
f =
if, R3 =
4 CR R1
f
R2 + R1
Figure 16. Multiple Feedback Bandpass Filter
Figure 15. Function Generator
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