ADC Effective Resolution Calculator

This tool calculates the effective resolution of an ADC as well as the noise free resolution.

Note: Effective resolution should not be confused with Effective Number of Bits ENOB, although they sound very similar

Enter:

  • Number of ADC Bits (n)
  • Peak to peak Noise in least significant bits (LSB)

	

			

		

						

				

				

                

			

			
						

		

		











Example Calculation





The noise free resolution of a 24 bit converter with peak to peak noise of 6 LSBs is 21 bits and the effective resolution is 23.7 





The Effective resolution is never greater than the ADC resolution. For example, a 12-bit converter cannot have an effective resolution greater
than 12 bits.





Background





Effective resolution and noise-free resolution measure the ADC’s noise performance at essentially DC, where spectral distortion (THD, SFDR) is not factored. 





The noise-free resolution of an Analog-to-Digital Converter (ADC) refers to the number of effective bits (ENOB) of an ADC that are free from noise, essentially quantifying the ADC’s precision in the presence of noise. It provides an understanding the real-world performance of an ADC, as it accounts for not only the quantization error but also the noise that affects the conversion process.





In theory, the resolution of an ADC is determined by its bit count; for example, a 12-bit ADC theoretically can resolve 1 part in 4096. However, in practice, electronic noise—originating from the ADC itself, the input signal, or the environment—limits the actual usable resolution. The noise-free resolution gives a more accurate indication of how many bits of the ADC’s output can be reliably used for noise-free measurements.





References





[1]  Understanding Noise, ENOB, and Effective Resolution in Analog-to-Digital Converters





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