Simple decoupling circuit for DACs?

[eVITAERC]

(cross-posted form Power Supply Design, because nobody goes there)

Hi guys,

I'm planning an ultra-portable stereo designed to hook up to a laptop. The plan is to have the DAC (I'm using diyparadise's Monica 2) and a custom class-D amp run off the same 12V switching power supply that the laptop is using, while the laptop runs in power-saving mode operated by a remote.

The general circuit tests out, and everything can run without hitting current output limits on the SMPS. However the problem is that there is inavoidably a lot of noise in the PS, whether it's from the class-D or the laptop or the PSU itself. Is there a simple LC-decoupling/bypassing circuit that I can use to decouple the entire noise-sensitive DAC without lowering the supply voltage? What would be suitable values?


Thanks in advance

 

[bocka]

Have you made some measurements about the noise on the output of the class D amp or the DAC? Is the noise present at the DACs output first or on the class D amp? Did you use a star topology for grounding?

Although a SMPS creates (much) more noise than a standard linear regulator noise problems are most often grounding problems as the PSRR of the chips is high enough to supress power supply related noise.