Employ best design practices when laying out a printed circuit board (PCB) for both analog and digital components. The PCM186x-Q1 audio ADC is a relatively simple device to lay out, even on a two-layer PCB. The following basic recommendations for layout of the PCM186x-Q1 help achieve the best possible performance of the device.
The EVM user’s guide shows the schematics, a bill of material, and a more detailed PCB layout.
Use the same plane for analog and digital grounds to avoid any potential voltage difference between these grounds. On the PCM186x-Q1 EVM, maximum SNR performance is achieved by using a single ground plane, and making sure that the return currents for digital signals are not near the AGND pin or the input signals.
As shown in Figure 74, the pin layout of the PCM186x-Q1 is partitioned into two sections: analog and digital. No digital return currents (for example, clocks) are generated in the analog circuitry, as long as the system is partitioned in such a way that digital signals are routed away from the analog sections.