[AK4480]
It is recommended in SACD format book (the Scarlet Book) that the filter response at SACD playback is an analog low
pass filter with a cut-off frequency of maximum 50kHz and a slope of minimum -30dB/Oct. The AK4480 can achieve this
filter response by combination of the internal filter (Table 25) and an external filter (Figure 21).
Frequency
20kHz
50kHz
Gain
−0.4dB
−2.8dB
−15.5dB
100kHz
Table 25. Internal Filter Response at DSD Mode
2.0k
1.8k
1.8k
4.3k
AOUT-
AOUT+
1.0k
1.0k
270p
2.4Vpp
2.4Vpp
2200p
+Vop
3300p
4.3k
-
2.0k
Analog
Out
5.42Vpp
+
-Vop
270p
Figure 21. External 3rd Order LPF Circuit Example for DSD
Frequency
20kHz
50kHz
Gain
−0.05dB
−0.51dB
−16.8dB
100kHz
DC gain = 1.07dB
Table 26. 3rd Order LPF (Figure 21) Response
MS1146-E-03
2012/01
- 41 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
