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Chapter 8 Tutorial
Measurement Fundamentals
Loading Errors Due to Input Resistance Measurement loading
errors occur when the resistance of the device-under-test ( DUT ) is an
appreciable percentage of the instrument's own input resistance.
The diagram below shows this error source.
R
S
HI
V
S
LO
Where:
V
= Ideal DUT voltage
s
R
= DUT source resistance
s
R
= Input resistance (10 M or >10 G )
i
100 x R
s
Error (%) =
R
R
i
s
To minimize loading errors, set the DMM 's dc input resistance to
greater than 10 G when needed (for more information on dc input
resistance, see page 113).
R
DMM
i
8
357
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