AKD4626A-B Datasheet, PDF (7/44 Pages) Asahi Kasei Microsystems – Multi-channel Audio CODEC.

ASAHI KASEI
[AKD4626A-B]
c) Frequency response of filter
Frequency response of the 1st-order filter
| Amplitude |² = K*{1+(f/fc₂)²}/{1+(f/fc₁)²};
K = 1+4.7k/4.7k = 2,
fc₁ = 1/2πRC = 102.7kHz@R=4.7k,C=330p,
fc₂ = K*fc₁ = 205.3kHz
Frequency response referenced to output level of this board is as following table:
fin
DC
20kHz
40kHz
80kHz
Frequency Response
0dB
-0.121dB -0.452dB -1.448dB
145kHz
-3dB
∞
-6dB
If the frequency response of filter influences the system, 1st-order LPF is also available as the following figure:
3.0Vpp
AK4626A
ROUT1 28
LOUT1 27 ^{Same circuit}
22u
10k
ROUT2 26 ^{Same circuit}
LOUT2 25 ^{Same circuit}
ROUT3 24 ^{Same circuit}
LOUT3 23 ^{Same circuit}
NJM4580
+
-
4.7k
4.7k
LPF
220
3300p
6.0Vpp
Signal
Frequency response of this LPF
| Amplitude |² = 1/{1+(f/fc)²};
fc = 1/2πRC = 219kHz@R=220,C=3300p
Frequency response referenced to output level of this board is as following table:
fin
DC
20kHz
40kHz
80kHz
Frequency Response
0dB
-0.036dB -0.142dB -0.543dB
219kHz
-3dB
∞
-∞dB
The total frequency response of this board is sum of the external filter and internal LPF of AK4626A.
These filters are effective to attenuate the high frequency noise since some measurement units is sensitive for out-of-band noise.
<KM079800>
-7-
2005/11