MC3403, MC3303
R
C1
V
in
C
−
MC3403
+
V
ref
V
ref
R2
R1
Bandpass
Output
−
T
BP
= center frequency gain
T
N
= passband notch gain
V
ref
MC3403
+
1/2
1/2
R
100 k
C
−
100 k
f
o
=
1
2pRC
V
ref
=
1
V
2
CC
R1 = QR
R2 = R1
T
BP
R3 = T
N
R2
C1 = 10 C
R2
MC3403
+
V
ref
1/2
−
MC3403
+
1/2
R = 160 kW
C = 0.001
mF
R1 = 1.6 MW
R2 = 1.6 MW
R3 = 1.6 MW
R3
C1
Notch Output
For: f
o
Q
T
BP
T
N
= 1.0 kHz
= 10
=1
=1
Where:
Figure 13. Bi−Quad Filter
V
CC
C
V
in
R1
C
R3
−
MC3403
+
1/2
C
O
V
O
C
O
= 10 C
1
V
2
CC
V
ref
=
1
V
2
CC
Triangle Wave
Output
+
MC3403
−
C
R
f
f=
R1 +R
C
4 CR
f
R1
if R3 =
R2 R1
R2 +R1
1/2
R2
R2
300 k
R3
+
75 k
R1
100 k
V
ref
MC3403
−
1/2
V
ref
Given:
Square Wave
Output
f
o
= center frequency
A(f
o
) = gain at center frequency
V
ref
V
ref
=
Choose value f
o
, C
Then:
R3 =
Q
p
f
o
C
R1 =
R3
2 A(f
o
)
R2 =
R1 R5
4Q
2
R1 −R5
O
o
f
o
For less than 10% error from operational amplifier
< 0.1
BW
where f
o
and BW are expressed in Hz.
If source impedance varies, filter may be preceded with
voltage follower buffer to stabilize filter parameters.
Figure 14. Function Generator
Figure 15. Multiple Feedback Bandpass Filter
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