wm8941 Wolfson Microelectronics plc, wm8941 Datasheet - Page 90

• Manufacturer Part Number: wm8941
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

WM8941
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NOTCH FILTERS AND LOW PASS FILTER
Figure 54 ADC Notch Filter Responses (48kHz); fc=100Hz, 1kHz, 10kHz; fb = 100Hz, 600Hz, 2kHz
Figure 55 ADC Low Pass Filter Responses (48kHz); fc= 1kHz, 5kHz, 10kHz
R
E
S
P
O
N
S
E
(dB)
R
E
S
P
O
N
S
E
(dB)
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
+0
-5
-10
-15
-20
-25
-30
-35
-40
-45
-50
-55
-60
+0
20
-5
20
50
50
The WM8941 supports four programmable notch filters. The fourth notch filter can be configured as a
low pass filter. The following illustrates three digital notch filters, followed by a single low pass filter in
the ADC filter path. Both the centre frequency and -3dB bandwidth are programmable for the notch
filters. The cut off frequency is programmable for the low pass filter. The following graphs show the
responses of 1) a single notch filter at three chosen centre frequencies, with three bandwidths for
each, 2) the low pass filter at three chosen cut off frequencies and 3) the cascade of three notch
filters followed by the low pass filter, each with a different centre / cut off frequency with three
bandwidths for each.
100
100
200
200
500
500
Frequency (Hz)
Frequency (Hz)
1k
1k
2k
2k
5k
5k
10k
PD, Rev 4.0, August 2008
10k
20k
Production Data
20k
T T
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