Datasheet

28
32 60 32
b
0
28
32 60
b
1
S
28
32 60
b
2
60
28
60 32
a
1
28
60 32
a
2
M0012-01
z
–1
z
–1
Magnitude
Truncation
z
–1
z
–1
GainCoefficient
32
SDIN1-L
28
60
GainCoefficient
32
28
60
SUM
GainCoefficient
32
28
60
M0011-01
SDIN1-R
SDIN4-R
TAS5548
www.ti.com SLES270 –NOVEMBER 2012
Figure 3-11. Input Crossbar Mixer
3.4 Biquad Filters
For 32-kHz to 96-kHz data, the TAS5548 provides 56 biquads across the eight channels (seven per
channel).
For 176.4-kHz and 192-kHz data, the TAS5548 has 32 biquads across the three channels (seven per
channel).
The direct form I structure provides a separate delay element and mixer (gain coefficient) for each node in
the biquad filter. Each mixer output is a signed 60-bit product of a signed 32-bit data sample (9.23 format
number) and a signed 28-bit coefficient (5.23 format number), as shown in Figure 3-12. The 60-bit ALU in
the TAS5548 allows the 60-bit resolution to be retained when summing the mixer outputs (filter products).
All of the biquad filters are second-order direct form I structure.
The five 28-bit coefficients for the each of the 56 biquads are programmable via the I
2
C interface. See
Table 3-1.
Figure 3-12. Biquad Filter Structure
Copyright © 2012, Texas Instruments Incorporated TAS5548 DAP Architecture 21
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