LOG102 Datasheet, PDF (12/15 Pages) Texas Instruments – LOGARITHMIC AND LOG RATIO AMPLIFIER

≈ 1.003 log
10 ^–6
10 ^–7
+ 0.004 + 0.003
(10)
= 1.003 (1) + 0.004 + 0.0003
(11)
= 1.0073V
(12)
Since the ideal output is 1.000V, the error as a percent of
reading is
% error = ^0.0073 • 100% = 0.73%
(13)
1
For the case of voltage inputs, the actual transfer function is
V_OUT = (1V) (1± ∆K)log
V₁
R₁
–
I_B1
±
E_OS1
R₁
V₂
R₂
– I_B2
±
E_OS2
R₂
(14)
± 2Nn ± V_{OS OUT}
Where
E_{OS1 and} E_OS2
R₁
R₂
(15)
are considered to be zero for large
values of resistance from external input current sources.
12
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LOG102
SBOS211A