PCM3010

SLES055 – NOVEMBER 2002

20

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DAC portion

The DAC portion is based on the delta-sigma modulator, which consists of an 8-level amplitude quantizer and

a 4th-order noise shaper. This section converts the oversampled input data to the 8-level delta-sigma format.

A block diagram of the 8-level delta-sigma modulator is shown in Figure 41. This 8-level delta-sigma modulator

has the advantage of improved stability and clock jitter over the typical one-bit (2-level) delta-sigma modulator.

The combined oversampling rate of the delta-sigma modulator and the internal 8

all system clocks. The theoretical quantization noise performance of the 8-level delta-sigma modulator is shown

in Figure 42.

+

+

–

Z–1

+

++

+

+

+

8-Level Quantizer

–

Z–1

IN

8 fS

OUT

64 fS

+

+

Z–1

+

+

Z–1

Figure 41. 8-Level Delta-Sigma Modulator Block Diagram