**Q: How is the input referred noise of an ADC related to its signal-to-noise ratio (SNR)?**

**A: They are related, but only if you compare them under the same test conditions.**

Learn more about ADC input noise in Apples and Oranges, as published in the November 2012 issue of *Analog Dialogue*.

We welcome your feedback. Has this article helped you in your design? Would you like more information on this topic?

Best regards,

Scott

Hi,

Thanks for your many great articles on numerous topics.

My question: I don't understand where the "2" comes from in the denominator of the input noise formula in the article. I understand where the "root(2)" comes from, but I'm a bit confused by the "2" in front of the "root(2)". I did my best to derive the formula on my own, and I can see where everything comes from, except for the "2".

I tried the "example" you put in the article on my calculator. I can only get match your answer of 1.47 LSB if I leave out the "2". Is the "2" perhaps a typo, or is there something I'm missing?

Thanks