ASAHI KASEI
[AK4644]
De-emphasis Filter
The AK4644 includes the digital de-emphasis filter (tc = 50/15µs) by IIR filter. Setting the DEM1-0 bits enables the
de-emphasis filter (Table 37).
DEM1
DEM0
Mode
44.1kHz
OFF
48kHz
32kHz
0
0
1
1
0
1
0
1
Default
Table 37. De-emphasis Control
Bass Boost Function
The BST1-0 bits control the amount of low frequency boost applied to the DAC output signal (Table 38). If the BST1-0
bits are set to “01” (MIN Level), use a 47µF capacitor for AC-coupling. If the boosted signal exceeds full scale, the analog
output clips to the full scale. Figure 38 shows the boost frequency response at –20dB signal input.
Boost Filter (fs=44.1kHz)
0
-5
MID
-10
MIN
-15
-20
-25
10
100
1000
10000
Frequency [Hz]
Figure 38. Bass Boost Frequency Response (fs=44.1kHz)
BST1
BST0
Mode
OFF
MIN
MID
MAX
0
0
1
1
0
1
0
1
Default
Table 38. Bass Boost Control
MS0477-E-01
2006/10
- 48 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
