adau1373 Analog Devices, Inc., adau1373 Datasheet - Page 63

• Manufacturer Part Number: adau1373
• Description: Low Power Codec With Speaker And Headphone Amplifier Adau1373
• Manufacturer: Analog Devices, Inc.

COEFFICIENT CALCULATIONS
Peak Filter Setting
With f
required peak filter center frequency, BW as the bandwidth,
and G (dB) as the gain, use the following steps for coefficient
calculation:
1.
2.
3.
4.
Low-Pass Shelving Filter
The low-pass shelving filter transfer function is
With f
filter cutoff frequency, and G (dB) as the gain, use the following
steps for coefficient calculation:
1.
Transfer the gain in decibels (dB) to decimal domain.
Calculate the double precision coefficients.
Transfer the double precision coefficients to integer values
represented by registers.
p0 = round(p0 × 8192)
p1 = round(p1 × 8192)
p2 = round(p2 × 8192)
d1 = round(d1 × 8192)
d2 = round(d2 × 8192)
Transfer the decimal integer values to 16-bit, twos
complement hexadecimal values.
Transfer the gain in decibels (dB) to decimal domain.
α
d1
d2
k =
k =
β
H
p0
p1
p2
S
S
=
(
as the input signal sampling frequency, f
as the input signal sampling frequency, f
=
=
=
=
=
=
z
10
10
1 (
)
cos(
1 (
−
−
1 (
1 (
=
20
G
−
cos(
α
20
1 (
G
+
+
−
p0
sin(
α
1
+
k
k
f
f
−
C
)
)
BW
S
)
α
+
×
f
+
BW
+
d1
)
S
×
f
p1
1 (
β
2
×
S
1 (
2
2
×
×
β
π
−
×
+
×
2
z
)
k
π
z
k
−
2
1
)
−
π
)
)
1
×
×
))
α
α
C
as the required
C
as the
Rev. 0 | Page 63 of 296
2.
3.
4.
High-Pass Shelving Filter
The high-pass shelving filter transfer function is
With f
filter cutoff frequency, and G (dB) as the gain, use the following
steps for coefficient calculation:
1.
2.
3.
4.
Calculate the double precision coefficients.
Transfer the double precision coefficients to integer values
represented by registers.
p0 = round(p0 × 8192)
p1 = round(p1 × 8192)
d1 = round(d1 × 8192)
Transfer the decimal integer values to twos complement
hexadecimal values.
Transfer the gain in decibels (dB) to decimal domain.
Calculate the double precision coefficients.
Transfer the double precision coefficients to integer values
represented by registers.
p0 = round(p0 × 8192)
p1 = round(p1 × 8192)
d1 = round(d1 × 8192)
Transfer the decimal integer values to twos complement
hexadecimal values.
α
α
d1
H
k =
d1
p0
p1
p0
p1
S
=
(
=
as the input signal sampling frequency, f
=
=
=
z
=
=
=
10
)
1 (
1 (
α
α
(
1 (
1 (
1 (
=
k
20
G
−
cos(
−
cos(
+
+
−
−
p0
sin(
1
sin(
k
k
) 1
k
−
)
)
+
)
f
f
f
f
d1
+
−
+
−
C
C
S
S
p1
f
f
f
f
1 (
1 (
1 (
C
1 (
2
2
C
2
2
S
S
×
×
×
×
×
×
−
+
−
+
2
z
2
z
π
−
π
2
2
k
k
k
k
1
−
π
π
)
)
)
)
)
)
1
×
×
×
×
))
))
α
α
α
α
C
as the required
ADAU1373