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17.7.2.6 Code jitter, non-monotonicity, and missing codes
Analog-to-digital converters are susceptible to three special forms of error. These are
code jitter, non-monotonicity, and missing codes.
Code jitter occurs when, at certain points, a given input voltage converts to one of two
values when sampled repeatedly. Ideally, when the input voltage is infinitesimally
smaller than the transition voltage, the converter yields the lower code (and vice-versa).
However, even small amounts of system noise can cause the converter to be
indeterminate, between two codes, for a range of input voltages around the transition
voltage. This range is normally around ±1/2 lsb in 8-bit or 10-bit mode, or around 2 lsb in
12-bit mode, and increases with noise.
This error may be reduced by repeatedly sampling the input and averaging the result.
Additionally the techniques discussed in
Noise-induced errors
reduces this error.
Non-monotonicity is defined when, except for code jitter, the converter converts to a
lower code for a higher input voltage. Missing codes are those values that are never
converted for any input value.
In 8-bit or 10-bit mode, the ADC is guaranteed to be monotonic and have no missing
codes.
MC9S08SU16 Reference Manual, Rev. 5, 4/2017
288
NXP Semiconductors
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