WM8998 datasheet(24/307 Pages) WOLFSON

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WM8998

Production Data

PD, October 2014, Rev 4.0

TERMINOLOGY

Signal-to-Noise Ratio (dB) – SNR is a measure of the difference in level between the maximum full scale output signal and the

output with no input signal applied. (Note that this is measured without any mute function enabled.)

Total Harmonic Distortion (dB) – THD is the ratio of the RMS sum of the harmonic distortion products in the specified

bandwidth (see note below) relative to the RMS amplitude of the fundamental (ie. test frequency) output.

Total Harmonic Distortion plus Noise (dB) – THD+N is the ratio of the RMS sum of the harmonic distortion products plus noise

in the specified bandwidth (see note below) relative to the RMS amplitude of the fundamental (ie. test frequency) output.

Power Supply Rejection Ratio (dB) - PSRR is the ratio of a specified power supply variation relative to the output signal that

results from it. PSRR is measured under quiescent signal path conditions.

Common Mode Rejection Ratio (dB) – CMRR is the ratio of a specified input signal (applied to both sides of a differential

input), relative to the output signal that results from it.

Channel Separation (L/R) (dB) – left-to-right and right-to-left channel separation is the difference in level between the active

channel (driven to maximum full scale output) and the measured signal level in the idle channel at the test signal frequency.

The active channel is configured and supplied with an appropriate input signal to drive a full scale output, with signal measured

at the output of the associated idle channel.

Multi-Path Crosstalk (dB) – is the difference in level between the output of the active path and the measured signal level in the

idle path at the test signal frequency. The active path is configured and supplied with an appropriate input signal to drive a full

scale output, with signal measured at the output of the specified idle path.

Mute Attenuation – This is a measure of the difference in level between the full scale output signal and the output with mute

applied.

All performance measurements are specified with a 20kHz low pass ‘brick-wall’ filter and, where noted, an A-weighted filter.

Failure to use these filters will result in higher THD and lower SNR readings than are found in the Electrical Characteristics.

The low pass filter removes out of band noise.

WM8998 Datasheet(PDF) 24 Page - Wolfson Microelectronics plc