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AK4643 Datasheet, PDF (42/104 Pages) Asahi Kasei Microsystems – Stereo CODEC with MIC/HP/RCV/SPK-AMP | |||
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ASAHI KASEI
[AK4643]
[Filter Coefficient Setting]
1) When FIL1 and FIL2 are set to âHPFâ
fs: Sampling frequency
fc: Cut-off frequency
f: Input signal frequency
K: Filter gain [dB] (Filter gain of should be set to 0dB.)
Register setting
FIL1: F1AS bit = â0â, F1A[13:0] bits =A, F1B[13:0] bits =B
FIL3: F3AS bit = â0â, F3A[13:0] bits =A, F3B[13:0] bits =B
(MSB=F1A13, F1B13, F3A13, F3B13; LSB=F1A0, F1B0, F3A0, F3B0)
1 / tan (Ïfc/fs)
A = 10K/20 x
,
1 + 1 / tan (Ïfc/fs)
1 â 1 / tan (Ïfc/fs)
B=
1 + 1 / tan (Ïfc/fs)
Transfer function
Amplitude
Phase
1 â z â1
H(z) = A
1 + Bz â1
M(f) = A
2 â 2cos (2Ïf/fs)
1 + B2 + 2Bcos (2Ïf/fs)
(B+1)sin (2Ïf/fs)
θ(f) = tan â1
1 - B + (Bâ1)cos (2Ïf/fs)
2) When FIL1 and FIL2 are set to âLPFâ
fs: Sampling frequency
fc: Cut-off frequency
f: Input signal frequency
K: Filter gain [dB] (Filter gain of FIL1 should be set to 0dB.)
Register setting
FIL1: F1AS bit = â1â, F1A[13:0] bits =A, F1B[13:0] bits =B
FIL3: F3AS bit = â1â, F3A[13:0] bits =A, F3B[13:0] bits =B
(MSB=F1A13, F1B13, F3A13, F3B13; LSB=F1A0, F1B0, F3A0, F3B0)
1
A = 10K/20 x
,
1 + 1 / tan (Ïfc/fs)
1 â 1 / tan (Ïfc/fs)
B=
1 + 1 / tan (Ïfc/fs)
Transfer function
Amplitude
Phase
1 + z â1
H(z) = A
1 + Bz â1
M(f) = A
2 + 2cos (2Ïf/fs)
1 + B2 + 2Bcos (2Ïf/fs)
(Bâ1)sin (2Ïf/fs)
θ(f) = tan â1
1 + B + (B+1)cos (2Ïf/fs)
MS0476-E-01
- 42 -
2006/10
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