Datasheet

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SLES014B − OCTOBER 2001 − REVISED AUGUST 2002
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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 FilterBand 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
‡
f
c
= 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).