LM2902
TYPICAL SINGLE - SUPPLY APPLICATIONS
ACTIVER BANDPASS FILTER
HIGH INPUT Z, DC DIFFERENTIAL AMPLIFIER
R
R
R4
R3
1
For
=
2
R1
100k
(CMRR depends on this resistor ratio match)
Ω
C1
330pF
1/4
LM2902
R5
Ω
470k
R4
R2
Ω
Ω
R4
10M
e 1
100k
100k
Ω
1/4
LM2902
R1
100k
Ω
C2
R3
100k
330pF
Ω
1/4
LM2902
R3
R6
Ω
10k
Ω
470k
1/4
V
o
LM2902
eO
+V1
+V2
1/4
LM2902
R7
100k
Ω
VCC
C3
R8
100k
R4
R3
µ
10 F
Ω
eo (1+
) (e − e1)
2
As shown eo = (e2 - e1)
FO = 1kHz
Q = 50
AV = 100 (40dB)
USING SYMMETRICAL AMPLIFIERS TO REDUCE INPUT CURRENT (GENERAL CONCEPT)
1/4
LM2902
e o
I I
I
B
e I
I
I
B
B
2N 929
µ
0.001 F
I
B
1/4
LM2902
Ω
3M
Aux. a mplifier for input
current compensation
I
B
Ω
1.5M
9/14
STMICROELECTRONICS [ ST ]
