wm8952 Wolfson Microelectronics plc, wm8952 Datasheet - Page 23

• Manufacturer Part Number: wm8952
• Description: Mono Adc With Microphone Pre-amplifier
• Manufacturer: Wolfson Microelectronics plc

Pre Production
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Figure 11 Labelling of Notch Filters and Arrangement of Notch Filter Enables
PROGRAMMABLE NOTCH FILTERS
Table 15 Notch Filter 0 Function
Four programmable notch filters are provided. These filters have a programmable centre frequency
and bandwidth, programmable via two coefficients, a0 and a1. a0 and a1 are represented by the
register bits NFx_A0[13:0] and NFx_A1[13:0]. The notch filter coefficients should be converted to
sign / magnitude notation to enter into the registers. Notch Filter 3 can also be programmed as a 1
order low pass filter.
Because these coefficient values require two register writes to set up there is an NFx_UP (Notch
Filter Update) flag for each filter which should be set only when both A0 and A1 for the filter have
been set.
The notch filters can be individually enabled, using the corresponding NFx_EN register bit, as can be
seen in Figure 11:
The notch filter coefficients must be entered using a sign / magnitude notation.
R16
Notch Filter 0A
R17
Notch Filter 0B
REGISTER
ADDRESS
15
14
13:0
15
13:0
BIT
NF0_UP
NF0_EN
NF0_A0
NF0_UP
NF0_A1
LABEL
0
0
0
0
0
DEFAULT
Notch filter 0 update. The notch filter 0
values used internally only update when
one of the NF0_UP bits is set high.
Notch filter 0 enable:
0=Disabled
1=Enabled
Notch Filter 0 a0 coefficient
Notch filter 0 update. The notch filter 0
values used internally only update when
one of the NF0_UP bits is set high.
Notch Filter 0 a1 coefficient
PP, Rev 3.0, December 2008
DESCRIPTION
WM8952
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