2
1MΩ
R
F
4
This OPT301 used
as photodiode, only.
2
1MΩ
R
F
4
NC
40pF
V
O
=
75Ω
5
R
1
+ R
2
R
2
I
D
R
F
40pF
λ
OPT301
8
1
V+
3
V–
75Ω
R
1
19kΩ
R
2
1kΩ
λ
OPT301
I
D1
8
1
3
5
NC
2
Advantages: High gain with low resistor values.
Less sensitive to circuit board leakage.
Disadvantage: Higher offset and noise than by using high
value for R
F
.
40pF
1MΩ
R
F
4
FIGURE 5. “T” Feedback Network.
75Ω
λ
OPT301
2
1MΩ
R
F1
4
5
V
O
V
O
= (I
D2
– I
D1
) R
F
I
D2
8
1
V+
3
V–
40pF
Bandwidth is reduced to
2.8kHz due to additional
photodiode capacitance.
75Ω
FIGURE 7. Differential Light Measurement.
5
V
O
= I
D1
R
F1
+ I
D2
R
F2
λ
OPT301
8
1
V+
Max linear
input voltage
(V+) –0.6V typ
2
1MΩ
R
F2
3
V–
6
2
1MΩ
R
F
4
40pF
75Ω
4
λ
OPT301
I
D
8
1
+15V
3
–15V
5
40pF
R
1
1kΩ
75Ω
λ
OPT301
8
1
V+
3
V–
5
V
O
= I
D2
R
F2
I
O
≤
5mA
I
O
= I
D
1 +
R
F
R
1
FIGURE 6. Summing Output of Two OPT301s.
FIGURE 8. Current Output Circuit.
®
9
OPT301
BURR-BROWN [ BURR-BROWN CORPORATION ]
