PCB Return current plane in a case of dual-rail power supply (two-layer pcb)

[NigthMoth]

Hello all

I’m wondering whether pcb ground/return current plane should be V- or RefGND for circuits with dual-rail power supply (V+,V-, RefGND) and split power supply op-amps?

I plan to design an audio circuit and build it on two-layer pcb. It will be powered from dual rail power supply: V+,V-,RefGND. On-board op-amps will use V+ and V- for power supply, op-amps output ac signals will oscillate around RefGND.

I red some articles (“How to Design Your PCB Return Current Path“, “PCB Layout Tips and Tricks: Use a Ground Plane Whenever Possible“) and realized that even for 1kHz signals it is better to implement return current path, and using ground plane is the easiest way to do it.
(Please correct me if I wrong)

Now I’m wondering: what voltage should I use for pcb ground/return current plane for circuit with split power supply op-amps: RefGND or V- ?
It will be two-layer pcb, so I can have only one ground plane.

V- is most negative, so it looks like all currents should return to V- terminal, but ac signals change its polarity/current flow direction, so maybe RefGnd is better?

 

[G4BCH]

I can have only one ground plane.

The answer is in the name 'Ground Plane'.
Use 0V ground reference, both supplies will return current to this.