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LOG114_12 Datasheet, PDF (17/29 Pages) Burr-Brown (TI) – Single-Supply, High-Speed, Precision LOGARITHMIC AMPLIFIER | |||
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LOG114
www.ti.com
NEGATIVE INPUT CURRENTS
The LOG114 functions only with positive input currents
(conventional current flows into input current pins). In
SBOS301A â MAY 2004 â REVISED MARCH 2007
situations where negative input currents are needed,
the example circuits in Figure 7, Figure 8, and Figure 9
may be used.
IIN
QA
D1
QB
National
LM394
D2
OPA 70 3
Figure 7. Current Inverter/Current Source.
+3.3V
+5V
1/2
OPA2335
1kâ¦
(+3.3V
10nA to 1mA Back Bias)
Photodiode
IOUT
1.5kâ¦
+5V
1/2
OPA2335
BSH203
LOG114
10nA to 1mA
Pin 3 or Pin 4
Figure 8. Precision Current Inverter/Current Source.
10nA to 1mA
+3.3V
Back Bias
+3.3V
Photodiode
1kâ¦
+5V
1/2
OPA2335
Figure 9. Precision Current Inverter/Current Source.
100kâ¦
100kâ¦
+5V
1/2
OPA2335
1.5kâ¦
1.5kâ¦
100kâ¦
100kâ¦
10nA to 1mA
Pin 3 or Pin 4
LOG114
17
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