ADC Effective Number of Bits

Last modified by Microchip on 2023/11/10 11:07

The Effective Number Of Bits (ENOB) value for an Analog-to-Digital Converter (ADC) is computed by substituting the measured Signal-to-Noise Ratio plus Distortion (SINAD) value into the equation that describes the Signal-to-Noise Ratio (SNR) for an ideal ADC and solving for N (number of bits). The equation below shows the calculation for ENOB.


The ENOB is usually presented for a range of input frequencies and tells the designer how accurate the converter is as a function of input frequency and the chosen sampling rate. The figure below shows a graphical example of ENOB data taken from an ADC. Note that the sampling frequency and operating conditions have been specified.

graph to explain the effective number of bits

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