DSP IC supply

[blackfin]

yung linear regulator mababa ang efficiency kasi yung output driver nya kelangan meron bias, so kahit naka idle, kumakain ng current.
normally switching regulator ang ginagamit for efficiency. saka mas madaling i-control between active and idle states nung dsp.

bat kaya di na lang nila nilagyan ng internal linear reg. para meron ng 1.8V sa loob?

[blackfin]

true. digital/switching circuits generates noise and harmonics

It is one of concepts na dapat matutunan. At DC, the two points are connected. But at high frequencies magkahiwalay dapat sila or else noise from the digital ground will mix with the analog signal. The A/D conversions magkaka-error.

Secondly, the ground line is not a single point. Sa schematic diagram, it seems to be. But sa actual PCB, it is a trace of copper. Depending on where the current is flowing, there are small differences in voltage along the trace. You must know where to connect the analog ground to the digital ground where it picks up the least noise.