I am using a microcontroller with an integrated DAC. On my 4 layer PCB, I have connected the digital and the analog ground planes below the microcontroller.
The microcontroller and the DAC are supplied by a 3.3V regulator.
The DAC amplifier is supplied by a 5V regulator.
See the following picture?
- Which ground plane (GND or AGND) should the 5V regulator be referenced to?
- Which ground plane should the DAC amplifier supply (and its decoupling capacitor) be referenced to?