CS5571

DS768A5

21

6/25/07

14:12

This excellent DNL performance impacts small-signal performance. For small signals, an error in the size

of a code represents a much greater percentage of the signal than with a full-scale input signal. Figure

10 illustrates the small-signal performance of the CS5571. The signal is at -80 dB from full scale. There-

lent DNL and proper dither allows the CS5571 to achieve high spectral purity with very small signals.

Figure 10. CS5571 Small Signal Performance (Dither On)

Figure 11. CS5571 Small Signal Performance (Dither Off)

Figure 11 illustrates the performance of the CS5571 under the same signal conditions as figure 10 but

with DITHER set to OFF. For small signals, good DNL alone is not adequate as the quantization itself can

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Input Signal = 1 kHz @ -80 dB

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DITHER ON

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DITHER OFF