MC92307 Datasheet, PDF (1/10 Pages) Motorola, Inc – 2K - Samples FFT-Processor

MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Current information @www.mot.com.sps/ADC
MC92307
Advance Information
2K - Samples FFT-Processor
The MC92307 is a pipelined Fast Fourier Transformation (FFT) processor with a
blocklength of 2048 complex samples. It is especially designed for use in digital ter-
restrial Set-Top boxes according to the DVB-T standard for 2K transmission. One
block of 2048 complex samples can be processed in 224 µs
Feature Summary
• Processing of one block of 2048 complex samples (i.e. one 2K-OFDM symbol) in
224 µs.
• Designed for direct interfacing with Motorola’s OFDM demodulator MC92308.
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Input wordlength 8 bit, output accuracy selectable between 10 and 12 bit.
Overflow on certain OFDM subcarriers due to co-channel interferes is handled in-
n ternally.
tio ^{Readout of output samples can be shifted by half the blocklength to start at the}
middle of the output block.
a ^{Either multiplexed or non-multiplexed input and output format (the multiplexed}
mode allows direct interfacing with Motorola’s OFDM Demodulator MC92308).
m _{Internal Bit reversal can be disabled to allow the construction of FFT modules for}
r _{blocklengths > 2K by using several devices in parallel.}
fo ^{Low clock rate inputs and outputs.}
In ^{0.5µm CMOS process at 3.3 V.}
5 V tolerant inputs and outputs.
inary _NOMUX
lim ^{DIN 8}
DINR 8
Input
16
FFT (11 stages)
24
e ^Buffer
incl. Rounding
Pr ^FFTSTART
RESB
CLK
FFTSTART
Control
Twiddle Factor ROM
RESB
CLK
SYMSYNC
DOUT[11:0]
DOUTR[11:0]
NOMUX
OFFSET
RES[1:0]
FFTSTART
DIN[7:0]
DINR[7:0]
Ordering Information
Device
MC92307CI
Package
160QFP
Output
Reorder
Buffer
12 DOUT
12 DOUTR
SYMSYNC
OFFSET
RES[1:0]
REVRSB
Figure 1. Block diagram of the FFT processor MC92307
This document contains information on a new product.
Specifications and information herein are subject to change without notice.
© MOTOROLA, INC. 1997
8/12/97