Production Data
Notes:
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2.
Ratio of output level with 1kHz full scale input, to the output level with all zeros into the digital input, measured ‘A’
weighted.
WM8768
All performance measurements done with 20kHz low pass filter, and where noted an A-weight filter. Failure to use
such a filter will result in higher THD+N and lower SNR and Dynamic Range readings than are found in the Electrical
Characteristics. The low pass filter removes out of band noise; although it is not audible it may affect dynamic
specification values.
VMID decoupled with 10uF and 0.1uF capacitors (smaller values may result in reduced performance).
The performance of each DAC is measured separately
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4.
TERMINOLOGY
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2.
Signal-to-noise ratio (dB) - SNR is a measure of the difference in level between the full scale output and the output
with no signal applied. (No Auto-zero or Automute function is employed in achieving these results).
Dynamic range (dB) - DNR is a measure of the difference between the highest and lowest portions of a signal.
Normally a THD+N measurement at 60dB below full scale. The measured signal is then corrected by adding the 60dB
to it. (e.g. THD+N @ -60dB= -32dB, DR= 92dB).
THD+N (dB) - THD+N is a ratio of the rms values of (Noise + Distortion)/Signal.
Stop band attenuation (dB) - Is the degree to which the frequency spectrum is attenuated (outside audio band).
Channel Separation (dB) - Also known as crosstalk. This is a measure of the amount one channel is isolated from
the other. Normally measured by sending a full scale signal down one channel and measuring the other.
Pass-Band Ripple - Any variation of the frequency response in the pass-band region.
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PD Rev 4.1 March 2005
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
