11.1 Layout Guidelines

Capacitive coupling between the noisy digital circuitry and the sensitive analog circuitry can lead to poor performance. The solution is to keep the analog circuitry separated from the digital circuitry.

Generally, analog and digital lines must cross each other at 90° to avoid crosstalk. However, to maximize accuracy in high resolution systems, avoid crossing analog and digital lines altogether.

The analog input must be isolated from noisy signal traces to avoid coupling of spurious signals into the input. Any external component (for example, a filter capacitor) connected between the converter's input pins and ground must be connected to a clean point of the ground.

A 0.1-µF capacitor must be placed close to the supply pin of the ADC121S101.

11.2 Layout Example

Figure 24. ADC121S101 Sample Layout