ponent (e.g., a filter capacitor) connected between the con-

verter’s input and ground should be connected to a very

clean point in the analog ground return.

Figure 7 gives an example of a suitable layout, including

power supply routing, ground plane separation, and bypass

capacitor placement. All analog circuitry (input amplifiers, fil-

ters, reference components, etc.) should be placed on or

over the analog ground plane. All digital circuitry and I/O

lines should be over the digital ground plane.

Digital and analog signal lines should never run parallel to

each other in close proximity with each other. They should

only cross each other when absolutely necessary, and then

only at 90˚ angles. Violating this rule can result in digital

noise getting into the input, which degrades accuracy and

dynamic performance (THD, SNR, SINAD).

DS100897-21

FIGURE 7. An acceptable layout pattern

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