Electrical Characteristics
LM2904
Figure 20. Non-inverting DC gain
Figure 21. DC summing amplifier
e1
100k
Ω
R2
R1
AV= 1 +
10k
Ω
A
(As shown V = 101)
eO
eO
1/2
LM2904
1/2
LM2904
+5V
100k
Ω
e2
e3
100k
100k
Ω
Ω
R2
Ω
1M
100k
Ω
R1
10k
Ω
e4
100k
Ω
eo = e1 + e2 - e3 - e4
where (e1 + e2) ≥ (e3 + e4)
to keep eo ≥ 0V
0
eI
(mV)
Figure 22. High input Z, DC differential
amplifier
Figure 23. Using symmetrical amplifiers to
reduce input current
1/2
LM2904
eo
I I
I
B
eI
I
I
B
R4
100k
R2
100k
2N 929
Ω
Ω
R1
100k
Ω
R3
100k
Ω
0.001 F
µ
1/2
LM2904
1/2
LM2904
V
o
+V1
+V2
I
B
B
1/2
LM2904
If R1 = R5 and R3 = R4 = R6 = R7
2R1
R2
Ω
3M
I
eo = [ 1 +
] (e2 - e1)
As shown eo = 101 (e2 - e1)
Input current compensation
B
1.5M
Ω
Figure 24. Low drift peak detector
Figure 25. Active bandpass filter
R1
100k
I
B
Ω
C1
330pF
1/2
LM2904
eo
1/2
LM2904
R2
100k
I
B
R5
470k
Ω
1/2
LM2904
Ω
+V1
Zo
R4
10M
C
2I
Ω
eI
B
1/2
LM2904
µ
1 F
C2
330pF
ZI
R6
470k
2N 929
R3
100k
Ω
0.001
µ
F
Ω
Vo
1/2
LM2904
R7
100k
I
2I
B
B
Ω
VCC
1/2
LM2904
R
1M
C3
10
3R
3M
R8
100k
Ω
µ
F
Ω
Ω
Fo = 1kHz
Q = 50
Av = 100 (40dB)
Input current
compensation
I
B
10/15
STMICROELECTRONICS [ ST ]
