Absolute Error

The absolute error is the maximum deviation between the ideal straight line and the actual transfer function, including the quantization steps. The minimum absolute error is therefore ½ LSB, due to quantization.

Absolute error or absolute accuracy is the total uncompensated error and includes quantization error, offset error, gain error, and non-linearity. Offset, gain, and non-linearity are described later in this document.

Absolute error can be measured using a ramp input voltage. In this case all output values are compared against the input voltage. The maximum deviation gives the absolute error.

Note: Absolute error cannot be compensated for directly, without using e.g. memory-expensive look-up tables or polynomial approximations. However, the most significant contributions to the absolute error - the offset and gain error - can be compensated for.

Be aware that the absolute error represent a reduction in the ADC range, and one should therefore consider the margins to the minimum and maximum input values to avoiding clipping keeping the absolute error in mind.