WM8781
Production Data
DIGITAL FILTER CHARACTERISTICS
The WM8781 digital filter characteristics scale with sample rate.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
ADC Sample Rate (Single Rate – 48Hz typically)
Passband
+/- 0.01dB
-6dB
0
0.4535fs
+/- 0.01
0.4892fs
Passband Ripple
Stopband
dB
0.5465fs
-65
Stopband Attenuation
Group Delay
f > 0.5465fs
dB
fs
22
ADC Sample Rate (Dual Rate – 96kHz typically)
Passband
+/- 0.01dB
0
0.4535fs
+/- 0.01
-6dB
0.4892fs
Passband Ripple
Stopband
dB
0.5465fs
-65
Stopband Attenuation
Group Delay
f > 0.5465fs
dB
fs
22
Table 8 Digital Filter Characteristics
ADC FILTER RESPONSES
0.02
0.015
0.01
0
-20
-40
-60
-80
0.005
0
-0.005
-0.01
-0.015
-0.02
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0
0.5
1
1.5
2
2.5
3
Frequency (Fs)
Frequency (Fs)
Figure 12 Digital Filter Frequency Response
Figure 13 ADC Digital Filter Ripple
PD, April 2006, Rev 4.1
16
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
