WM8768 Wolfson Microelectronics plc, WM8768 Datasheet - Page 36

• Manufacturer Part Number: WM8768
• Description: 24-bit, 192khz 8-channel Dac
• Manufacturer: Wolfson Microelectronics plc

WM8768
SUGGESTED ANALOGUE LOW PASS POST DAC FILTERS
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It is recommended that a lowpass filter be applied to the output from each DAC channel for Hi Fi
applications. Typically a second order filter is suitable and provides sufficient attenuation of high
frequency components (the unique low order, high bit count multi-bit sigma delta DAC structure used
in WM8768 produces much less high frequency output noise than normal sigma delta DACs. This
filter is typically also used to provide the 2x gain needed to provide the standard 2Vrms output level
from most consumer equipment. Figure 32 shows a suitable post DAC filter circuit, with 2x gain.
Alternative inverting filter architectures might also be used with as good results.
Figure 32 Recommended Post DAC Filter Circuit
VOUT1R
VOUT2R
VOUT3R
VOUT4R
VOUT1L
VOUT2L
VOUT3L
VOUT4L
10uF
47k
1.8k
680pF
7.5k
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
OP_FIL
1.0nF
4.7k
4.7k
OP_FIL
51
PD Rev 4.2 July 2005
Production Data
36