I'm designing a 120A 4 phase step down power supply, and require a 6 layer 2OZ PCB to meet current carrying capacity requirements. There will be a mix of sensitive analogue and digital in my purpose built multiphase controller consisting a mixture of op-amps, discrete transistors, high speed comparators, ADC, DAC, programmable logic & a microcontroller.
Is it feasible to separate analogue and digital components so they are placed directly on opposites sides of the PCB, and use separate non-isolated ground planes ?
I am speculating that return currents from digital lines should only flow in the adjacent ground plane layer, and not interfere with subsequent ground and signal layers. For a 6 layer stack I am considering:
[analogue components]-------------------------- L1 analogue signal L2 ground L3 power (analogue) L4 power (digital) L5 ground L6 digital signal
------------------------ [Digital components]
L2 and L5 will be connected only in limited locations.
Adam Seychell