LF43881
DEVICES INCORPORATED
8 x 8-bit Digital Filter
LF43881
DEVICES INCORPORATED
8 x 8-bit Digital Filter
DESCRIPTION
The
LF43881
is a video-speed digital
filter that contains eight filter cells
(taps) cascaded internally and a shift-
and-add output stage. An 8 x 8
multiplier, three decimation registers,
and a 26-bit accumulator are con-
tained in each filter cell. The output
stage of the LF43881 contains a 26-bit
accumulator which can add the
contents of any filter stage to the
output stage accumulator shifted right
by 8 bits. 8-bit unsigned or two’s
complement format for data and
coefficients can be independently
selected.
Expanded coefficients and word sizes
can be processed by cascading mul-
tiple LF43881s to implement larger
filter lengths without affecting the
sample rate. By reducing the sample
rate, a single LF43881 can process
larger filter lengths by using multiple
passes. The sampling rate can range
from 0 to 40 MHz. Over 1000 taps
may be processed without overflows
due to the architecture of the device.
The output sample rate can be re-
duced to one-half, one-third, or one-
fourth the input sample rate by using
the three decimation registers con-
tained in every filter cell. Matrix
multiplication, N x N spatial correla-
tions/convolutions, and other 2-D
operations for image processing can
also be achieved using these registers.
FEATURES
u
u
u
u
25 MHz Maximum Sampling Rate
320 MHz Multiply-Accumulate Rate
8 Filter Cells
8-bit Unsigned or Two’s Complement
Data
u
8-bit Unsigned or Two’s Complement
Coefficients
u
26-bit Data Outputs
u
Shift-and-Add Output Stage for
Combining Filter Outputs
u
Expandable Data Size, Coefficient
Size, and Filter Length
u
User-Selectable 2:1, 3:1, or 4:1
Decimation
u
Replaces Harris HSP43881
u
84-pin PLCC, J-Lead
LF43881 B
LOCK
D
IAGRAM
DIN
7-0
8
DIENB, CIENB,
ERASE, DCM
1-0
5
TCS
TCCI
CIN
7-0
ADR
2-0
8
FILTER
CELL 0
8
FILTER
CELL 1
8
FILTER
CELL 2
8
FILTER
CELL 3
8
FILTER
CELL 4
8
FILTER
CELL 5
8
FILTER
CELL 6
8
FILTER
CELL 7
TCCO
8
COUT
7-0
COENB
3
26
26
26
26
26
26
26
26
MUX
26
SHADD
SENBL
SENBH
RESET
26
OUTPUT
STAGE
TO ALL CELLS
CLK
TO ALL REGISTERS
SUM
25-0
Video Imaging Products
1
08/16/2000–LDS.43881-J
LOGIC [ LOGIC DEVICES INCORPORATED ]
