TFA9812HN PHILIPS [NXP Semiconductors], TFA9812HN Datasheet - Page 17

• Manufacturer Part Number: TFA9812HN
• Description: BTL stereo Class-D audio amplifier with I2S input
• Manufacturer: PHILIPS [NXP Semiconductors]

NXP Semiconductors
TFA9812_2
Preliminary data sheet
In the above equation f
The definition of the quality factor is the center frequency divided by the 3 dB bandwidth,
see
( 30 dB).
Each band filter can be programmed to perform a band-suppression (G < 1) or a
band-amplification (G > 1) function around the center frequency.
Each band of the TFA9812 equalizer has a second-order Regalia-Mitra all-pass filter
structure. The structure is shown in
The transfer function of this all-pass filter is shown in
A(z) is the second-order filter structure. The transfer function of A(z) is shown in
Equation
The relationship between the programmable parameters K
parameters G, , Q is shown in
Use
Use
Q
H z
K
A z
Fig 5.
2
=
=
Equation
Equation 4
Equation 5
-----------------;
=
f
=
2
2Q G
f
-------------------------------------------------------------------------------- -
1
–
1 2
c
Regalia filter flow-diagram
3:
K
+
f
X(z)
1
1
K
+
K
2
1. In parametric equalizers this is only valid when the gain is set very small
–
K
1
1
K
s
sin
to calculate band suppression (G < 1) functions.
to calculate band amplification (G
2
+
=
0
1
A z
+
=
f
f
–
1
1
2
cos
K
:
:
G
+
Rev. 02 — 22 January 2009
1
c
K
2Q G
+
is the center frequency and f
A(z)
1
Z
K
1 –
20
20
0
Z
+
10
10
1 –
2
+
K
log
log
+
Equation 4
+
sin
1
1
Z
–
2 –
Z
------- -
------- -
A
A
A
A
Figure
BTL stereo Class-D audio amplifier with I
2 –
A z
f
f
f
f
1
c
2
c
G 1
+
5.
+
and
=
=
½
Equation
3dB f
3dB f
K
1) functions.
0
,
s
/2
Equation
is the sample frequency.
c
2
5.
f
f
0
1
c
, K
1
2:
, and K
2
© NXP B.V. 2009. All rights reserved.
TFA9812
010aaa406
and the filter
Y(z)
2
S input
17 of 66
(1)
(2)
(3)
(4)