Datasheet
SINC FILTERRESPONSE
3 (1)
Frequency(Hz)
0
-20
-40
-60
-80
-100
-120
0 625k312.5k 937.5k 1562.5k
Gain(dB)
SINC FILTERRESPONSE
2 (1)
Frequency(Hz)
0
-20
-40
-60
-80
-100
-120
0 625k312.5k 937.5k 1562.5k
Gain(dB)
SINCFASTFILTERRESPONSE
(1)
Frequency(Hz)
0
-20
-40
-60
-80
-100
-120
0 625k312.5k 937.5k 1562.5k
Gain(dB)
SINC
1
FILTERRESPONSE
(1)
Frequency(Hz)
0
-20
-40
-60
-80
-100
-120
0 625k312.5k 937.5k 1562.5k
Gain(dB)
NOTE:(1) 312.5kHz=f =
DATA
f
OSR
CLK
=
10MHz
32
AMC1210
www.ti.com
.............................................................................................................................................................. SBAS372D – APRIL 2006 – REVISED MAY 2009
Figure 15. AMC1210 Frequency Responses with Various Sinc Filters
These figures show the digital filter frequency response for one oversampling ratio (SOSR = 32) and a modulator
rate of 10MHz.
The general purpose of the digital filter is to average the input modulator data. Achieving higher resolution
requires additional samples for averaging, thereby increasing the total samples necessary to accurately
represent an abrupt change. It also requires additional clock cycles to complete a single sample. The ratio of
clock cycles to output samples is controlled by the SOSR value (the oversampling ratio for the sinc filter unit) in
the Sinc Filter Parameter Register . Table 10 and Figure 16 show the maximum resolution given different filter
structures and SOSR values.
Table 10. Peak Data Values for Different SOSR/Filter Combinations
SOSR Sinc
1
Sinc
2
Sinc
3
Sincfast
x x x
2
x
3
2x
2
4 – 4 to 4 – 16 to 16 – 64 to 64 – 32 to 32
8 – 8 to 8 – 64 to 64 – 512 to 512 – 128 to 128
16 – 16 to 16 – 256 to 256 – 4096 to 4096 – 512 to 512
32 – 32 to 32 – 1024 to 1024 – 32,768 to 32,768 – 2048 to 2048
64 – 64 to 64 – 4096 to 4096 – 262,144 to 262,144 – 8192 to 8192
128 – 128 to 128 – 16,384 to 16, 384 – 2,097,152 to 2,097,152 – 32,768 to 32,768
256 – 256 to 256 – 65,536 to 65,536 – 16,777,216 to 16,777,216 – 131,072 to 131,072
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