Texas Instruments TLV320AIC3105 Evaluation Module (EVM) and USB motherboard TLV320AIC3105EVM-K TLV320AIC3105EVM-K 데이터 시트
제품 코드
TLV320AIC3105EVM-K
DIGITAL AUDIO PROCESSING FOR PLAYBACK
H(z)
+
N0
)
N1
z
*
1
32768
*
D1
z
*
1
(2)
ǒ
N0
)
2
N1
z
*
1
)
N2
z
*
2
32768
*
2
D1
z
*
1
*
D2
z
*
2
Ǔǒ
N3
)
2
N4
z
*
1
)
N5
z
*
2
32768
*
2
D4
z
*
1
*
D5
z
*
2
Ǔ
(3)
LB1
LB2
RB1
RB2
B0154-01
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SLAS513B – FEBRUARY 2007 – REVISED DECEMBER 2008
The DAC channel consists of optional filters for de-emphasis and bass, treble, midrange level adjustment,
speaker equalization, and 3-D effects processing. The de-emphasis function is implemented by a programmable
digital filter block with fully programmable coefficients (see page 1, registers 21–26 for left channel, page 1,
registers 47–52 for right channel). If de-emphasis is not required in a particular application, this programmable
filter block can be used for some other purpose. The de-emphasis filter transfer function is given by:
speaker equalization, and 3-D effects processing. The de-emphasis function is implemented by a programmable
digital filter block with fully programmable coefficients (see page 1, registers 21–26 for left channel, page 1,
registers 47–52 for right channel). If de-emphasis is not required in a particular application, this programmable
filter block can be used for some other purpose. The de-emphasis filter transfer function is given by:
where the N0, N1, and D1 coefficients are fully programmable individually for each channel. The coefficients that
should be loaded to implement standard de-emphasis filters are given in
should be loaded to implement standard de-emphasis filters are given in
Table 3. De-Emphasis Coefficients for Common Audio Sampling Rates
SAMPLING FREQUENCY
N0
N1
D1
32 kHz
16,950
–1,220
17,037
44.1 kHz
15,091
–2,877
20,555
48 kHz
(1)
14,677
–3,283
21,374
(1)
The 48-kHz coefficients listed in
are used as defaults.
In addition to the de-emphasis filter block, the DAC digital effects processing includes a fourth-order digital IIR
filter with programmable coefficients (one set per channel). This filter is implemented as cascade of two biquad
sections with frequency response given by:
filter with programmable coefficients (one set per channel). This filter is implemented as cascade of two biquad
sections with frequency response given by:
The N and D coefficients are fully programmable, and the entire filter can be enabled or bypassed. The structure
of the filtering when configured for independent channel processing is shown below in
of the filtering when configured for independent channel processing is shown below in
, with LB1
corresponding to the first left-channel biquad filter using coefficients N0, N1, N2, D1, and D2. LB2 similarly
corresponds to the second left-channel biquad filter using coefficients N3, N4, N5, D4, and D5. The RB1 and
RB2 filters refer to the first and second right-channel biquad filters, respectively.
corresponds to the second left-channel biquad filter using coefficients N3, N4, N5, D4, and D5. The RB1 and
RB2 filters refer to the first and second right-channel biquad filters, respectively.
Figure 25. Structure of the Digital Effects Processing for Independent Channel Processing
The coefficients for this filter implement a variety of sound effects, with bass boost or treble boost being the most
commonly used in portable audio applications. The default N and D coefficients in the part are given in
commonly used in portable audio applications. The default N and D coefficients in the part are given in
and implement a shelving filter with 0-dB gain from dc to approximately 150 Hz, at which point it rolls off to a
3-dB attenuation for higher frequency signals, thus giving a 3-dB boost to signals below 150 Hz. The N and D
coefficients are represented by 16-bit, 2s-complement numbers with values ranging from –32,768 to 32,767.
3-dB attenuation for higher frequency signals, thus giving a 3-dB boost to signals below 150 Hz. The N and D
coefficients are represented by 16-bit, 2s-complement numbers with values ranging from –32,768 to 32,767.
Copyright © 2007–2008, Texas Instruments Incorporated
35
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