LM2902
TYPICAL SINGLE - SUPPLY APPLICATIONS
ACTIVER BANDPASS FILTER
HIGH INPUT Z, DC DIFFERENTIAL AMPLIFIER
e1
R3
10kΩ
R1
100k Ω
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LM2902
R4
10MΩ
C2
330pF
R6
4 7 0 kΩ
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LM2902
R8
100kΩ
C1
330pF
1/4
LM2902
R5
4 7 0 kΩ
eO
R7
100kΩ
VCC
C3
10µF
FO = 1kHz
Q = 50
AV = 100 (40dB)
For
R1
R2
=
R4
R3
(CMRR depends on this resistor ratio match)
R2
100kΩ
R4
100kΩ
R1
100kΩ
R3
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100kΩ
+V1
LM29 02
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LM29 0 2
Vo
+V2
eo
(1+
R4
R3
)
(e2−
e1)
As shown eo = (e2 - e1)
USING SYMMETRICAL AMPLIFIERS TO REDUCE INPUT CURRENT (GENERAL CONCEPT)
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I I IB LM2902
eo
e I IB
2N 929
IB
1.5MΩ
0.001µF
IB
3MΩ
IB
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LM2902
Aux. a mplifier for input
current compe ns a tion
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