I'm designing a mixed-signal PCB and have been using this Maxim guide to help me with layout. The guide has instructed me to avoid making cuts to the PCB and instead think about ground return paths. By placing chips in strategic locations and orienting mixed signal chips properly I can avoid analog and digital return currents from overlapping.
I am aware that having digital ground currents run through analog circuitry will cause noise problems. In other words, the regulators (R), analog circuitry (A), and digital circuitry (D) should not be arranged in series like so: R - A - D.
Is the opposite also true? Is analog circuitry performance compromised if its ground return currents pass through digital circuitry? Using the acronyms above this would be: R - D - A.
I don't think this would cause problems assuming the analog regulator lines are routed through the perimeter of the PCB to avoid the digital circuitry. Mixed signal chips would be placed in between the two regions with the digital and analog sides of each chip facing the corresponding direction. Is this true? Or will I still run into noise issues?
EDIT: it looks like the guide I linked to already answers this question:
Therefore, if the analog and digital return currents (or any two currents) share a portion of the ground plane (i.e., their currents flow through the same metal) there will be crosstalk between the two as the copper resistance causes IR voltage drops.
This indicates that both approaches (R - A - D and R - D - A) are faulty and the circuitry must be laid out in parallel rather than sequentially to avoid this issue.
I will submit this as an answer unless someone has a better explanation.