10.1 Layout Guidelines

Each system design and printed circuit board (PCB) layout is unique. The layout must be carefully reviewed in the context of a specific PCB design. However, the following guidelines can optimize the device performance:

• Connect the thermal pad to ground. Use a via pattern to connect the device thermal pad, which is the area directly under the device, to the ground planes. This connection helps dissipate heat from the device.
• The decoupling capacitors for the power supplies must be placed close to the device pins.
• Route the analog differential audio signals differentially on the PCB for better noise immunity. Avoid crossing digital and analog signals to prevent undesirable crosstalk.
• The device internal voltage references must be filtered using external capacitors. Place the filter capacitors near the VREF pin for optimal performance.
• Directly tap the MICBIAS pin to avoid common impedance when routing the biasing or supply traces for multiple microphones to avoid coupling across microphones.
• Directly short the VREF and MICBIAS external capacitors ground terminal to the AVSS pin without using any vias for this connection trace.
• Place the MICBIAS capacitor (with low equivalent series resistance) close to the device with minimal trace impedance.
• Use ground planes to provide the lowest impedance for power and signal current between the device and the decoupling capacitors. Treat the area directly under the device as a central ground area for the device, and all device grounds must be connected directly to that area.