LF43168JC22 View Datasheet(PDF) - LOGIC Devices
Part Name
Description
MFG CO.
'LF43168JC22' PDF : 16 Pages View PDF
DEVICES INCORPORATED
LF43168
Dual 8-Tap FIR Filter
FIGURE 5. DECIMATING, EVEN-SYMMETRIC COEFFICIENT FILTER CONFIGURATIONS
N = Delay Length (Decimation Factor)
N
N
N
N = Delay Length (Decimation Factor)
N
N
N
DATA IN
N
N
N
A
B
B+A
A
B
B+A
A
B
B+A
A
B
B+A
DATA IN
N
N
N
A
B
B+A
A
B
B+A
A
B
B+A
A
B
B+A
Delay Stage N – 1 Output
COEF 0
COEF 1
COEF 2
COEF 3
EVEN-TAP FILTER
COEF 0
COEF 1
COEF 2
COEF 3
ODD-TAP FILTER
FIGURE 6. ODD-SYMMETRIC COEFFICIENT FILTER CONFIGURATIONS
DATA IN
A
B
B–A
A
B
B–A
A
B
B–A
A
B
B–A
N = Delay Length (Decimation Factor)
N
N
N
DATA IN
N
N
N
A
B
B–A
A
B
B–A
A
B
B–A
A
B
B–A
COEF 0
COEF 1
COEF 2
COEF 3
EVEN-TAP FILTER (NO DECIMATION)
COEF 0
COEF 1
COEF 2
COEF 3
DECIMATING, EVEN-TAP FILTER
Figure 5 shows the two possible
configurations when the device is
programmed as a decimating, even-
symmetric coefficient filter. The delay
length of the decimation registers will
be equal to the decimation factor that
the device is programmed for. Since
only four coefficients (effectively
eight) can be sent to the filter multipli-
ers on a clock cycle, it may be neces-
sary (depending on the coefficient set)
to change the coefficients fed to the
multipliers on different CLK cycles for
filters with more than eight taps. Note
that for the odd-tap filter, the middle
coefficient of the coefficient set must
be divided by two to get the correct
result.
Odd-Symmetric Coefficient Filters
Figure 6 shows the two possible
configurations when the device is
programmed for odd-symmetric
coefficients. Note that odd-tap, odd-
symmetric coefficient filters are not
possible.
Video Imaging Products
8
03/28/2000–LDS.43168-H
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