wm8953 Wolfson Microelectronics plc, wm8953 Datasheet - Page 38

• Manufacturer Part Number: wm8953
• Description: Low Power Stereo Adc With Pll And Tdm Interface Low Power Stereo Adc With Pll And Tdm Interface
• Manufacturer: Wolfson Microelectronics plc

WM8953
w
HIGH PASS FILTER
A digital high pass filter is applied by default to the ADC path to remove DC offsets. This filter can
also be programmed to remove low frequency noise in voice applications (e.g. wind noise or
mechanical vibration). This filter is controlled using the ADC_HPF_ENA and ADC_HPF_CUT register
bits.
In hi-fi mode the high pass filter is optimised for removing DC offsets without degrading the bass
response and has a cut-off frequency of 3.7Hz at fs=44.1kHz.
In voice mode the high pass filter is optimised for voice communication and it is recommended to
program
ADC_HPF_CUT=10 at fs=16kHz).
Table 15 ADC High Pass Filter Control Registers
Table 16 ADC High Pass Filter Cut-Off Frequencies
The high pass filter characteristics are shown in the "Digital Filter Characteristics" section.
REGISTER
ADDRESS
R14 (0Eh)
Frequency
Sample
11.025
16.000
22.050
24.000
32.000
44.100
48.000
8.000
(kHz)
the
8
6:5
BIT
cut-off
ADC_HPF_CUT
ADC_HPF_ENA
ADC_HPF_CUT
[1:0]
=00
0.7
0.9
1.3
1.9
2.0
2.7
3.7
4.0
frequency
LABEL
below
ADC_HPF_CUT
DEFAULT
1b
00b
Cut-off frequency (Hz)
127
175
190
253
348
379
=01
300Hz
64
88
(e.g.
ADC Digital High Pass Filter Enable
0 = disabled
1 = enabled
ADC Digital High Pass Filter Cut-Off
Frequency (fc)
00 = Hi-fi mode (fc=4Hz at fs=48kHz)
01 = Voice mode 1 (fc=127Hz at fs=16kHz)
10 = Voice mode 2 (fc=130Hz at fs=8kHz)
11 = Voice mode 3 (fc=267Hz at fs=8kHz)
(Note: fc scales with sample rate. See
Table 16 for cut-off frequencies at all
supported sample rates)
ADC_HPF_CUT
ADC_HPF_CUT=11
130
178
258
354
386
514
707
770
=10
DESCRIPTION
PD, January 2009, Rev 4.0
ADC_HPF_CUT
at
1063
1464
1594
Production Data
267
367
532
733
798
=11
fs=8kHz
38
or