The Broadcom BCM3137A1KEF QAMLinkUniversal QPSK/16 QAM Burst Receiver is a complete single-chip cable network receiver, that accepts QPSK and 16 QAM upstream burst data in a frequency-agile, time-division multiple access
(TDMA) scheme. An analog front-end (AFE),a QAM demodulator and an FEC decoder are integrated on this single chip. The AFE performs coarse gain setting and A-to-D conversion on either an IF input or baseband I/Q inputs.A digital down-mixer translates the input spectral center to true DC.
The I and Q samples pass through dual decimators and square-root raised cosine filters with an excess bandwidth a=0.25.Fast burst detection and acquisition are performed on the preamble with programmable length and pattern. The chipincorporates unique word (UW) detection in the preamble process to delineate the packet and resolve phase ambiguity.
Carrier phase offset is removed by a derotator. An adaptive equalizer characterizes the RF channel response and removes inter-symbol interference (ISI) caused by micro-reflections.
The FEC decoder consists of a programmable derandomizer anda programmable RS decoder. FIFO buffers provide input/output data rate de-coupling for the FEC decoder.
Feature
· The Broadcom BCM3137 is a headend QPSK/QAM burst receiver for CMTS applications
· DOCSIS/EuroDOCSIS, IEEE 802.14, DAVIC and DVB-compliant
· Programmable Demodulation: QPSK/16 QAM
· Variable symbol rates from 100 kBaud up to 5.12 MBaud
· Analog front-end featuring dual gain stages and dual 10-bit ADCs, plus a 6-bit ADC to estimate wideband channel
· Fast burst acquisition: preamble size as small as 4 bytes
· Programmable components include:
· Flexible symbol demapping: Differential/Non-Differential
· RS decoder block size(N), GF(256),T=1to 10
· Last RS codeword size: fixed or shortened·23-bit derandomizer: polynomial, seed, type
· Derandomizer location: before/after RS decoder
· Internal burst FIFOs for receive rate de-coupling
· Choice of serial data receive interfaces
· JTAG Test Interface
·100-pin PQFP Package
