Background: The design of the DAC noise monitor is in the PCB design stage - I am trying to put the circuit on the PCB board in Altium. We use three power voltages to drive the op amps in the circuit: -15 V. +15 V. We also need power ground and signal ground. This circuit is going to replace a part of a big PCB board with other existing circuits.

Question: What are the layers used by the existing design? The DAC noise monitor needs to fit with other parts, so they have to share the same layers. Is there a PCB layout file for the existing design?

In case of absence, I will start with a signal layer, a -15V power layer, a +15V power layer, a power ground, and a signal ground. I googled a bit and they say the cost will be high and five layers might be more than what we want. Besides, I am not sure about the sequence of the layers either. I will start with this in order to proceed in Altium before we figure out what we need to do:

TOP

Signal layer

+15V power

Power ground

Signal ground

-15V power

BOTTOM

How much sense does it make?