PCM1602 datasheet(29/29 Pages) TI

29 / 29 page

PCM1602

SBAS163

FIGURE 22. Test Set-Up for Dynamic Range and SNR Meeasurements.

S/PDIF

Receiver

Evaluation Board

PCM1602(1)

DEM-DAI1602

2nd-Order

Low-Pass

Filter

Notch Filter

Band Limit

HPF = 22Hz

LPF = 22kHz

C = 1kHz

–3dB = 54kHz

0% Full-Scale,

Dither Off (SNR)

–60dBFS,

1kHz Sine Wave

(Dynamic Range)

S/PDIF

Output

Option = A-Weighting(2)

A-Weight

Filter(1)

rms Mode

Analyzer

and

Display

Digital

Generator

DYNAMIC RANGE

Dynamic range is specified as A-Weighted, THD+N mea-

sured with a –60dBFS, 1kHz digital sine wave stimulus at

the input of the DAC. This measurement is designed to give

a good indication of how the DAC will perform, given a

low-level input signal.

The measurement setup for the dynamic range measurement

is shown in Figure 22, 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 –60dBFS input level.

IDLE CHANNEL SIGNAL-TO-NOISE RATIO

The SNR test provides a measure of the noise of the DAC.

The input to the DAC is in all “0”s data, and the DAC’s

Infinite Zero Detect Mute function must be disabled (de-

fault condition at power-up for the PCM1602). This en-

sures that the delta-sigma modulator output is connected to

the output amplifier circuit so that idle tones (if present)

may be observed at the output. The dither function of the

digital signal generator must also be disabled to ensure an

all “0”s data stream at the input of the DAC.

The measurement setup for SNR is identical to that used for

dynamic range, with the exception of the input signal level.

(see the notes provided in Figure 22.)

NOTES: (1) Infinite Zero Detect Mute disabled.

(2) Results without A-Weighting will be approxi-

mately 3dB worse.

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