WM8941GEFL WOLFSON [Wolfson Microelectronics plc], WM8941GEFL Datasheet - Page 91

• Manufacturer Part Number: WM8941GEFL
• Description: Mono CODEC with Speaker Driver and Video Buffer
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

Pre Production
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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
PP, Rev 3.3, December 2007
10k
10k
20k
20k
T T
WM8941
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