Datasheet

3−10
3.4 Biquad Filters
The TAS3103A has 73 biquad filters . The breakout of the biquad filters per functional element is given in Table 3−1.
Table 3−1. Biquad Filter Breakout
FUNCTION BIQUAD FILTERS SUBADDRESS
3D effects block 24 0x34−0x4B
Monaural channel CH1 12 0x4F−0x5A
Monaural channel CH2 12 0x5B−0x66
Monaural channel CH3 12 0x67−0x72
0xA6−CH1
Loudness processing 3
0xAB−CH2
Loudness processing
3
0xB0−CH3
Spectrum analyzer/VU meter 10 0xBC−0xC5
All 73 biquad filters are second-order direct-form I structures. A block diagram of the structure of the biquad filter is
shown in Figure 3−11.
b
0
b
1
b
2
a
1
a
2
28
28
28
28
28
48
76
76
48
48
76
76
76
48
48
76
Magnitude
Truncation
48
z
−1
z
−1
z
−1
z
−1
Σ
NOTE: All gain coefficients 5.23 numbers.
Biquad Filter Coefficient Subaddress Format
Biquad Filter Structure
m
s
b
S Slave Addr Ack Subaddr Ack xxx0000 Ack xxxxxxxx Ack xxxxxxxx Ack xxxxxx
l
s
b
Ack
a
1
m
s
b
xxx0000 Ack xxxxxxxx Ack xxxxxxxx Ack xxxxxx
l
s
b
Ack
a
2
m
s
b
xxx0000 Ack xxxxxxxx Ack xxxxxxxx Ack xxxxxx
l
s
b
Ack
b
0
m
s
b
xxx0000 Ack xxxxxxxx Ack xxxxxxxx Ack xxxxxx
l
s
b
Ack b
2
m
s
b
xxx0000 Ack xxxxxxxx Ack xxxxxxxx Ack xxxxxx
l
s
b
Ack
b
1
NOTE: Each biquad filter has one subaddress which contains the mixer gain coefficients a
1
, a
2
, b
0
, b
1
, b
2
Figure 3−11. Biquad Filter Structure and Coefficient Subaddress Format
The transfer function for the biquad filter is given by:
V
OUT
(z)
V
IN
(z)
+
b
0
) b
1
z
−1
) b
2
z
−2
1 * a
1
z
−1
* a
2
z
−2
Note that the signs of a
n
coefficients are opposite from Matlab-generated coefficients.