GF9101 Просмотр технического описания (PDF) - Gennum -> Semtech
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GF9101 Datasheet PDF : 23 Pages
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DATA_A_IN
0
1
2
3
4
5
6
7
8
9
10
11
CLK_IN
ENA
ENB
B
A
B
A
B
A
B
A
SEL_A/B
COEF_ADDR
(6 - 0)
00H
ENC
LOAD_EN
ZERO
CONFIGURE
B
A
B
A
FB _SEL
PIPELINE _OUT
Fig. 8 Timing Diagram for a 23-Tap Odd-Symmetric Filter
Assuming that the data A0 —> A21 has already been
shifted into the filter registers, by clocking ENA and ENB the
data A22 enters DATA_A_IN (Figure 9a). During the first
CLK_IN rising edge, the data in the A registers (A22 —>
A11) are selected by SEL_A/B , to be multiplied by the
coefficients, C0 —> C11 in memory location 0,
COEF_ADDR 00H . During the second CLK_IN rising edge
the data in B registers (A0 —> A10) are selected by SEL_A/
B, to be multiplied by the coefficients, C0 —>C10 (Figure
9b). After passing through the adder tree and the delay (4
CLK_IN cycles in total), the two sums are added in the
pipeline section of the filter. FB_SEL selects PIPELINE_IN
during CLK_IN period 5, at which time a DC offset could be
introduced at PIPELINE_IN to be added to the sum. During
CLK_IN period 6, FB_SEL selects PIPELINE_OUT and the
final filter sum is calculated and passed through to
PIPELINE_OUT.
DATA–A–IN
A22
A21
A20
A12
A11
DATA–B–OUT
A0
A1
A2
A10
x
C0
x C1
x
C2
x
C10
x C11
Σ
PIPELINED
ADDER
(A22 x C0) + (A21 x C1) + (A20 x C2) +...+(A12 x C10) + (A11 x C11)
DATA–A–IN A22
A21
DATA–B–OUT
A0
A20
A1
A12
A11
A2
A10
x
C0
x C1
x C2
x C10
x C11
Σ
PIPELINED
ADDER
(A22 x C0) + (A21 x C1) + (A20 x C2) +...+(A12 x C10) + (A11 x C11)
+
(A0 x C0) + (A1 x C1) + (A2 x C2) +...+(A10 x C10)
Fig. 9a Data Flow Diagram for a 23 Tap Odd-Symmetric Filter
Fig. 9b Data Flow Diagram for a 23 Tap Odd-Symmetric Filter
EVEN-TAP SYMMETRIC FILTER
The GF9101 can be configured as an even-tap symmetric
filter. A 24-tap symmetric filter can be configured using one
GF9101 by connecting the outputs of DATA_A_OUT to the
inputs of DATA_B_IN and taking the output at
PIPELINE_OUT. For a 24-tap symmetric filter, the
configuration word is shown in Table 9.
10
520 - 64 - 7
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