Figure 9-3 shows the layout of the geophone input application example of Figure 9-1. In most cases, a single unbroken ground plane connecting the grounds of the analog and digital components is preferred. A four-layer PCB is used, with the inner layers dedicated for ground and power-supply planes. Low resistance power-supply planes are necessary to maintain THD performance.

Connect the REFN pin of the ADC directly to the ground terminal of the voltage reference to avoid ground noise coupling. Similarly, avoid ground noise between the tie-points of termination resistors R₁ and R₂ by connecting the resistors together first, then connect to ground (dual-supply operation).

Place the smaller of the parallel power-supply bypass capacitors closest to the device supply pins. The thermal pad of the package connects to the most negative power-supply voltage (AVSS). Figure 9-3 shows single-supply operation, with AVSS tied to AGND. In this case, the thermal pad connects to AGND. For dual-supply operation, connect the thermal pad to AVSS.