Specifying the Maximum Amplifier Noise When Driving an ADC

Rick Lyons
3 comments

I recently learned an interesting rule of thumb regarding the use of an amplifier to drive the input of an analog to digital converter (ADC). The rule of thumb describes how to specify the maximum allowable noise power of the amplifier.



Comments:

alvinator
Said:
no comment at this time
4 years ago
0
Reply
Sorry, you need javascript enabled to post any comments.
audiosteve
Said:
looking forward to the article
4 years ago
0
Reply
Sorry, you need javascript enabled to post any comments.
smc123
Said:
Interesting article, as all of yours are. I don't disagree with the math or the conclusions, however, I think the criteria for determining the amplifier noise is a little timid. It's generally accepted that the best SNR is achieved when the full range of the ADC is utilized, and the amplifier gain is usually chosen to do so. And in the ideal case, the noise of the amplifier, multiplied by the gain, is small in comparison to the ADC noise. In this case where a gain of A is used, the SNR will be A times better than it is without an amplifier. So a higher criteria could be to choose an amplifier with noise that is not just A times less than the ADC noise, but maybe 0.2 times that figure, so that its contribution to the total noise is negligible. Of course, it depends on what is practically available for amplifiers, and what the ADC noise is, but in many cases there are amplifiers available to that will improve the SNR of a system that is not already using the full range of the ADC.
4 years ago
0
Reply
Sorry, you need javascript enabled to post any comments.
Sorry, you need javascript enabled to post any comments.