DAC frequency limitations; use of APLL

hpeteranvin
Posts: 29
Joined: Tue Feb 28, 2017 3:44 am

DAC frequency limitations; use of APLL

Postby hpeteranvin » Tue Apr 02, 2019 8:03 pm

Hi,

I wonder if anyone has any idea of what the practical frequency limits of the built-in DAC happens to be.
Also, the TDM states that when used in DAC mode one should use PLL_D2_CLK as the reference, but the top says that when using PLL_D2_CLK as a reference one should avoid fractional divisors. Are either of these negotiable?

ESP_Sprite
Posts: 9599
Joined: Thu Nov 26, 2015 4:08 am

Re: DAC frequency limitations; use of APLL

Postby ESP_Sprite » Wed Apr 03, 2019 3:59 am

I don't think there's a hard limit to the DAC frequency... I do know I've gotten a good 13MHz or so out of it, although I can't comment on the specifics wrt noise figures. Wrt trm: My guess is that you should avoid fractional divisors as they introduce jitter in the sampling rate, and you're better off just configuring the PLL for the rate you want instead.

hpeteranvin
Posts: 29
Joined: Tue Feb 28, 2017 3:44 am

Re: DAC frequency limitations; use of APLL

Postby hpeteranvin » Sat Apr 06, 2019 8:10 am

OK, so I am guessing you are telling me to use the APLL after all?
At that frequency it has a *lot* of potential.

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