LM2902W Datasheet, PDF (7/10 Pages) STMicroelectronics – LOW POWER QUAD OPERATIONAL AMPLIFIER

DC SUMMING AMPLIFIER
e ₁ 100kΩ
100k Ω
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LM2902
e_O
e ₂ 100kΩ
e ₃ 100kΩ
100k Ω
e ₄ 100kΩ
eo = e1 + e2 - e3 - e4
where (e1 + e2) ≥ (e3 + e4)
to keep eo ≥ 0V
HIGH INPUT Z ADJUSTABLE GAIN DC
INSTRUMENTATION AMPLIFIER
LM2902W
ACTIVER BADPASS FILTER
R1
100kΩ
e₁
R3
10kΩ
1/4
LM2902
R4
10MΩ
C2
330pF
R6
470kΩ
1/4
LM2902
Fo = 1kHz
Q = 50
Av = 100 (40dB)
R8
100kΩ
C1
330pF
1/4
LM2902
R5
470kΩ
R7
100kΩ
C3
10µF
e_O
V _CC
HIGH INPUT Z, DC DIFFERENTIAL AMPLIFIER
R1
100kΩ
e₁
R2
2kΩ
1/4
LM2902
Gain adjust
R5
100kΩ
R3
100k Ω
R4
100kΩ
1/4
e_O
LM2902
1/4
LM2902
R6
100kΩ
e₂
If R1 = R5 and R3 = R4 = R6 = R7
eo = [ 1 + 2R1 ] (e2 - e1)
R2
As shown eo = 101 (e2 - e1)
R7
100kΩ
R2
100k Ω
R4
100k Ω
R1
100k Ω
R3
1/4
100k Ω
+V1
LM2902
1/4
LM2902
Vo
+V2
eo = [ 1 + ^R4 ] (e2 - e1)
R3
As shown eo = (e2 - e1)
LOW DRIFT PEAK DETECTOR
I_B
1/4
1/4
I _B LM2902
e_o
LM2902
e_I
C
1µF _*
2I B
Z_o
Z_I
2N 929 _0.001µ_F
2IB
I_B
R
1MΩ
* Polycarbonate or polyethylene
3R
3MΩ
I_B
1/4
LM2902
Input current
compensation
USING SYMMETRICAL AMPLIFIERS TO
REDUCE INPUT CURRENT (GENERAL
CONCEPT)
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I_I
I _B LM2902
e_o
e_I
I_B
2N 929
I_B
1.5MΩ
0.001µ F
I_B
3MΩ
I_B
1/4
LM2902
Aux. amplifier for input
current compensation
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