Rainbow Electronics DS1867 - Manual (Page 8)

DS1867
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FIXED GAIN ATTENUATOR Figure 8
ABSOLUTE AND RELATIVE LINEARITY
Absolute linearity is defined as the difference between the actual measured output voltage and the
expected output voltage. Figure 9 presents the test circuit used to measure absolute linearity. Absolute
linearity is given in terms of a minimum increment or expected output when the wiper position is moved
one position. In the case of the test circuit, a minimum increment (MI) would equal 10/512volts. The
equation for absolute linearity is given in equation (1).
Eq: (1) Absolute Linearity
AL = {Vo(actual)- Vo(expected)}/MI
Relative linearity is a measure of error between two adjacent wiper position points and is given in terms
of MI by equation (2).
Eq: (2) Relative Linearity
RL = {Vo(n+1) - Vo(n)}/MI
Figure 10 is a plot of absolute linearity and relative linearity versus wiper position for the DS1867 at
25
°C. The specification for absolute linearity of the DS1867 is ±0.75 MI typical. The specification for
relative linearity of the DS1867 is
±0.30 MI typical.
LINEARITY MEASUREMENT CONFIGURATION Figure 9