ADS131M04-Q1
ZHCSOL7A –MARCH 2022 –REVISED AUGUST 2022
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8.3.7.2 Digital Filter Characteristic
方程式6 calculates the z-domain transfer function of a sinc3 filter that is used for OSRs of 1024 and lower.
3
1 - Z -N
H z
( )
=
N 1 - Z -1
(6)
where N is the OSR.
方程式7 calculates the transfer function of a sinc3 filter in terms of the continuous-time frequency parameter f.
3
Npf
sin
fMOD
H(f)½ =
pf
N ´ sin
fMOD
(7)
where N is the OSR.
图 8-4 and 图 8-5 show the digital filter response of the fast-settling filter and the sinc3 filter for OSRs of 1024
and lower. 图8-6 and 图8-7 show the digital filter response of the sinc3 + sinc1 filter for an OSR of 4096.
0
-20
0
-1.5
-3
-40
-4.5
-6
-60
-80
-7.5
-9
-100
-120
-140
-10.5
-12
Fast-settling filter
Sinc3 filter
Fast-settling filter
Sinc3 filter
0
0.1
0.2 0.3
Frequency (fIN/fDATA
0.4
0.5
0
1
2
3
Frequency (fIN/fDATA
4
5
)
)
图8-5. Fast-Settling and Sinc3 Digital Filter
图8-4. Fast-Settling and Sinc3 Digital Filter
Response, Pass-Band Detail
Response
0
0
-2
-4
-6
-8
Sinc3 filter (1024)
Sinc3 + Sinc1 filter
-20
-40
-60
-80
-100
-120
-140
-10
Sinc3 filter (1024)
Sinc3 + Sinc1 filter
-12
0
1
2
3
4
5
6
7
Frequency (f /fDATA
8
)
9
10 11 12
0
0.1
0.2 0.3
Frequency (f /fDATA
0.4
0.5
IN
)
IN
图8-6. Digital Filter Response for OSR = 1024 and
图8-7. Digital Filter Response for OSR = 1024 and
OSR = 4096
OSR = 4096, Pass-Band Detail
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