3.2 Even-Tap Symmetric Filter
The GF9101A can be configured as an even-tap symmetric
filter. A 24-tap symmetric filter can be configured using one
GF9101A by externally connecting the outputs of
DATA_A_OUT to the inputs of DATA_B_IN. For a 24-tap
symmetric filter, the configuration word is shown in Table 9.
Table 9: Configuration Word for a 24-Tap Symmetric Filter
BIT NO.
CONFIGURATION WORD
DESCRIPTION
0
1
2
3
4
5
6
1
1
Data A and B are signed data*
0
One register delay
0
0
24-tap filter, connect the outputs of DATA_A_OUT to the inputs of DATA_B_IN.
X
X
Depends on the loading mode (see Table 1)
* Bits 0 and 1 should have the same value for a 23 or 24 tap filter
The filter coefficients are shown in Figure 10. The timing is very similar to that of the odd-tap symmetric case.
C
C
11
11
C
C
10
10
C
C
9
9
C
C
4
4
C
C
5
5
(a) Filter Coefficients C
n
C
C
3
C
C
3
0
0
C
C
2
2
C
1
C
C
A
C
C
6
1
C
8
6
8
C
A
C
A
7
7
17
7
A
A
A
18
16
6
8
A
A
A
A
5
19
15
9
(b) Input Data A
n
A
A
4
A
A
20
A
0
24
A
14
10
A
A
A
11
A
21
13
23
A
A
1
3
A
A
12
A
2
22
Fig. 10 Input Data An and Coefficients Cn
11
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522 - 15 - 02
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