PCM1741ESLASH2K datasheet(19/24 Pages) TI2

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PCM1741

SBAS175

The theoretical quantization noise performance of the

8-level delta-sigma modulator is shown in Figure 15. The en-

hanced multilevel delta-sigma architecture also has advantages

for input clock jitter sensitivity due to the multilevel quantizer,

with the simulated jitter sensitivity, as shown in Figure 16.

KEY PERFORMANCE PARAMETERS

AND MEASUREMENT

This section provides information on how to measure key

dynamic performance parameters for the PCM1741. In all

cases, an Audio Precision System Two Cascade or equivalent

audio measurement system is utilized to perform the testing.

TOTAL HARMONIC DISTORTION + NOISE

Total Harmonic Distortion + Noise (THD+N) is a significant

figure of merit for audio DACs, since it takes into account

both harmonic distortion and all noise sources within a

specified measurement bandwidth. The true rms value of the

distortion and noise is referred to as THD+N. Figure 17

shows the test setup for THD+N measurements.

For the PCM1741, THD+N is measured with a full-scale,

1kHz digital sine wave as the test stimulus at the input of the

DAC. The digital generator is set to a 24-bit audio word

length and a sampling frequency of 44.1kHz or 96kHz. The

digital generator output is taken from the unbalanced

S/PDIF connector of the measurement system. The S/PDIF

FIGURE 16. Jitter Sensitivity.

100

200

300

400

500

600

125

120

115

110

105

100

Jitter (ps)

JITTER DEPENDENCE (64x Oversampling)

FIGURE 17. Test Setup for THD+N Measurements.

S/PDIF

Receiver

Evaluation Board

–3dB = 54kHz or 108kHz

PCM1741

DEM-DAI1741

2nd-Order

Low-Pass

Filter

Notch Filter

Band Limit

HPF = 22Hz

LPF = 30kHz

C = 1kHz

rms Mode

0dBFS,

1kHz Sine Wave

S/PDIF

Output

Analyzer

and

Display

20kHz

Apogee

Filter

Digital

Generator

FIGURE 15. Quantization Noise Spectrum.

–20

–40

–60

–80

–100

–120

–140

–160

–180

Frequency (f

QUANTIZATION NOISE SPECTRUM

(64x Oversampling)

QUANTIZATION NOISE SPECTRUM

(128x Oversampling)

–20

–40

–60

–80

–100

–120

–140

–160

–180

Frequency (f

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