AnsweredAssumed Answered

Why use randomization?

Question asked by johannes_bonn on Jun 26, 2018
Latest reply on Jun 28, 2018 by DougI

Dear all,

I seem to have some trouble understanding the benefits of output randomization, in my case using the LTM9009-14 series. I have to mention that I use it for sampling "slow" waveforms, and am not familiar with SDR applications, SINAD, SFDR, and so on.

Following the description in Digital Output Randomizer for High Speed ADCs | Analog Devices:

 

At first I just saw the effect that a transition at midscale 

0b01111111111111 -> 0b1000000000000

will turn to something much more interference friendly:

0b10000000000001-> 0b10000000000000

 

However those unfavorable transitions are, in the end, just moved to different locations.

In this case, it's even immediately clear from the reverse operation.

Going just one bit above midscale

0b10000000000000 -> 0b10000000000000 

0b10000000000001 -> 0b01111111111111 

and we are back with this unfortunate transition.

 

Can someone explain to me why the randomization is still useful?

Or is this in fact only relevant for SDR applications, because of the way how those transitions are moving from 2^N related positions to other positions?

 

Thanks!

 

Regards

Johannes

Outcomes