hey,
i am looking for an adc for a university project, while searching some components data sheets i stumbled across something i don't understand.
is there a difference between Noise Free Bits and Effective Number of Bit(ENOB)?
for example, you can see the table that i added.

 

You may want to give this a read.

i am looking for an adc for a university project, while searching some components data sheets i stumbled across something i don't understand.
is there a difference between Noise Free Bits and Effective Number of Bit(ENOB)?

The saying that "nothing is perfect" applies to an ADC as much as anything else. When designing a project, outside the walls of the classroom one must consider all of the variables including all of the allowable error. What can I live with and what is available and what will it cost for what I can live with or better?

All ADCs have noise and that noise is part of the resolution of the ADC. How much noise is acceptable in my design?

Specifications such as noise, effective number of bits (ENOB), effective resolution, and noise-free resolution in large part define how accurate an ADC really is. Consequently, understanding the performance metrics related to noise is one of the most difficult aspects of transitioning from a SAR to a delta-sigma ADC. With the current demand for higher resolution, designers must develop a better understanding of ADC noise, ENOB, effective resolution, and signal-to-noise ratio (SNR).

So if I have a 16 bit ADC with 2 bits of uncertainty or noise I have an effective 14 bit ADC and when I write my code (software) to read that ADC I want to shift my data two places, right shifting binary numbers would divide a number by 2 and left shifting the numbers would multiply it by 2. We would /2 or right shift. This is like saying Analog Input Channel 1 = Analog Input Channel divided by 2. While I have a 16 bit ADC in reality my effective bits are 14 bits.

Ron

 

You may want to give this a read.

The saying that "nothing is perfect" applies to an ADC as much as anything else. When designing a project, outside the walls of the classroom one must consider all of the variables including all of the allowable error. What can I live with and what is available and what will it cost for what I can live with or better?

All ADCs have noise and that noise is part of the resolution of the ADC. How much noise is acceptable in my design?

So if I have a 16 bit ADC with 2 bits of uncertainty or noise I have an effective 14 bit ADC and when I write my code (software) to read that ADC I want to shift my data two places, right shifting binary numbers would divide a number by 2 and left shifting the numbers would multiply it by 2. We would /2 or right shift. This is like saying Analog Input Channel 1 = Analog Input Channel divided by 2. While I have a 16 bit ADC in reality my effective bits are 14 bits.

Ron

thank you Ron

 

While I have a 16 bit ADC in reality my effective bits are 14 bits.

No. You have a 16 bit converter with 2 bits of noise. Significant difference! You can trade time for more bits. You can't do that* with a (solid) 14 bit converter.

*Actually you can by adding dithering. But that's extra. Batteries not included and some assembly required. YMMV.

 

No. You have a 16 bit converter with 2 bits of noise. Significant difference! You can trade time for more bits. You can't do that* with a (solid) 14 bit converter.

*Actually you can by adding dithering. But that's extra. Batteries not included and some assembly required. YMMV.

I agree.

Ron