LM324, LM324A, LM224, LM2902, LM2902V, NCV2902
1
2
Triangle Wave
Output
V
=
V
CC
R2
ref
300 k
V
+
ref
R3
75 k
R1
100 k
V
CC
1/4
LM324
+
1/4
LM324
R3
C
-
C
R1
Square
Wave
Output
-
C
-
V
in
O
1/4
LM324
V
V
ref
O
C
+
CO = 10 C
R2
R
f
R1 + R
V
ref
R2 R1
C
1
2
f =
if R3 =
V
ref
=
V
CC
4 CR R1
f
R2 + R1
Figure 16. Function Generator
Figure 17. Multiple Feedback Bandpass Filter
Given:ꢀf ꢁ=ꢁcenter frequency
o
A(f )ꢁ=ꢁgain at center frequency
o
Choose value f , C
o
Q
ꢄ f C
R3 =
R1 =
Then:
o
R3
2 A(f )
o
R1 R3
R2 =
2
4Q R1 - R3
Q f
o
o
< 0.1
For less than 10% error from operational amplifier,
BW
where f and BW are expressed in Hz.
o
If source impedance varies, filter may be preceded with
voltage follower buffer to stabilize filter parameters.
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