AK4691EG AKM [Asahi Kasei Microsystems], AK4691EG Datasheet - Page 37

• Manufacturer Part Number: AK4691EG
• Description: 4ch ADC + 2ch DAC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

[Filter Coefficient Setting]
1) When FIL1A(FIL1B) and FIL3A(FIL3B) are set to “HPF”
2) When FIL1A(FIL1B) and FIL3A(FIL3B) are set to “LPF”
MS0672-E-00
fs: Sampling frequency
fc: Cut-off frequency
f: Input signal frequency
K: Filter gain [dB] (Filter gain of FIL1A(FIL1B) should be set to 0dB.)
Register setting for ADC1
Register setting for ADC2
fs: Sampling frequency
fc: Cut-off frequency
f: Input signal frequency
K: Filter gain [dB] (Filter gain of FIL1A (FIL1B) should be set to 0dB.)
Register setting for ADC1
Register setting for ADC2
H(z) = A
H(z) = A
FIL1A: F1ASA bit = “0”, F1A[13:0]A bits =A, F1B[13:0]A bits =B
FIL3A: F3ASA bit = “0”, F3A[13:0]A bits =A, F3B[13:0]A bits =B
(MSB=F1A13A, F1B13A, F3A13A, F3B13A; LSB=F1A0A, F1B0A, F3A0A, F3B0A)
FIL1B: F1ASB bit = “0”, F1A[13:0]B bits =A, F1B[13:0]B bits =B
FIL3B: F3ASB bit = “0”, F3A[13:0]B bits =A, F3B[13:0]B bits =B
(MSB=F1A13B, F1B13B, F3A13B, F3B13B; LSB=F1A0B, F1B0B, F3A0B, F3B0B)
FIL1A: F1ASA bit = “0”, F1A[13:0]A bits =A, F1B[13:0]A bits =B
FIL3A: F3ASA bit = “0”, F3A[13:0]A bits =A, F3B[13:0]A bits =B
(MSB=F1A13A, F1B13A, F3A13A, F3B13A; LSB=F1A0A, F1B0A, F3A0A, F3B0A)
FIL1B: F1ASB bit = “0”, F1A[13:0]B bits =A, F1B[13:0]B bits =B
FIL3B: F3ASB bit = “0”, F3A[13:0]B bits =A, F3B[13:0]B bits =B
(MSB=F1A13B, F1B13B, F3A13B, F3B13B; LSB=F1A0B, F1B0B, F3A0B, F3B0B)
Transfer function
Transfer function
A = 10
A = 10
K/20
K/20
1 + Bz
1 + Bz
1 − z
1 + z
x
x
1 + 1 / tan (πfc/fs)
1 + 1 / tan (πfc/fs)
−1
−1
1 / tan (πfc/fs)
−1
−1
1
M(f) = A
M(f) = A
,
,
1 + B
1 + B
Amplitude
Amplitude
B =
B =
2 − 2cos (2πf/fs)
2 + 2cos (2πf/fs)
2
2
+ 2Bcos (2πf/fs)
+ 2Bcos (2πf/fs)
1 − 1 / tan (πfc/fs)
1 + 1 / tan (πfc/fs)
1 − 1 / tan (πfc/fs)
1 + 1 / tan (πfc/fs)
- 37 -
θ(f) = tan
θ(f) = tan
−1
−1
1 + B + (B+1)cos (2πf/fs)
1 - B + (B−1)cos (2πf/fs)
Phase
Phase
(B+1)sin (2πf/fs)
(B−1)sin (2πf/fs)
[AK4691]
2007/11