Analog Devices EVAL-ADAQ23876FMCZ User Manual page 14

User Guide
SOFTWARE OPERATION
INL Tab and DNL Tab
The INL tab and DNL tab display linearity analysis. INL is the
deviation of each individual code from a line drawn from negative
full scale through positive full scale. The point used as negative
full scale occurs ½ LSB before the first code transition. Positive full
scale is defined as a level 1½ LSB beyond the last code transition.
The deviation is measured from the middle of each code to the true
straight line.
In an ideal ADC, code transitions are 1 LSB apart. DNL is the
maximum deviation from this ideal value. DNL is often specified in
terms of resolution for which no missing codes are guaranteed.
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EVAL-ADAQ23876/EVAL-ADAQ23878
Figure 21. FFT with Oversampling (OSR) of 256×, Inputs Shorted
To perform a linearity test, apply a sinusoidal signal with 0.5
dB above full scale to the EVAL-ADAQ23876FMCZ or EVAL-
ADAQ23878FMCZ at the VIN+ and VIN− SMA inputs. Set the
number of hits per code and adjust to the desired accuracy. Using
a large number of hits per code results in a significant test time.
Figure 22 and Figure 23 display captured data that includes the
±INL and ±DNL positions.
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