PCM1606

SLES014B − OCTOBER 2001 − REVISED AUGUST 2002

24

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APPLICATION INFORMATION

total harmonic distortion + noise (continued)

S/PDIF

Receiver

Evaluation Board

DEM-DAI1606

PCM1606

2nd-Order

Low-Pass

Filter

Notch Filter

Band Limit

Analyzer

and

Display

Digital

Generator

S/PDIF

Output

100% Full-Scale,

24-Bit,

1-kHz Sine Wave

RMS Mode

HPF = 22 Hz†

LPF = 22 kHz†

Option = 20-kHz Apogee Filter‡

fc = 1 kHz

f−3 dB = 54 kHz

† There is little difference in measured THD+N when using the various settings for these filters..

‡ Required for THD+N test.

Figure 34. Test Setup for THD+N Measurements

dynamic range

Dynamic range is specified as A-weighted, THD+N measured with a –60 dB of full-scale (FS), 1-kHz digital sine

wave stimulus at the input of the D/A converter. This measurement is designed to give a good indicator of how

the DAC performs given a low-level input signal.

The measurement setup for the dynamic range measurement is shown in Figure 35, and is similar to the THD+N

test setup discussed previously. The differences include the band limit filter selection, the additional A-weighting

filter, and the –60-dB FS input level.

idle channel signal-to-noise ratio

The signal-to-noise ratio (SNR) test provides a measure of the noise floor of the D/A converter. The input to the

D/A is all 0s data. This ensures that the delta-sigma modulator output is connected to the output amplifier circuit

so that idle tones (if present) can be observed and affect the SNR measurement. The dither function of the digital

generator must also be disabled to ensure an all 0s data stream at the input of the D/A converter.

The measurement setup for SNR is identical to that used for dynamic range, with the exception of the input signal

level. (See the note provided in Figure 35).