BCM3142

Description

The BCM3142 QAMLink® Universal QPSK/QAM burst receiver is a highly integrated solution that significantly decreases the board space and cost of demodulators in digital cable modem headend applications. The BCM3142 provides 12 independent cable network receivers that accept QPSK and m-QAM burst data in TDMA or SCDMA schemes. Advanced features in the BCM3142 include an analog front end (AFE), a SCDMA despreader, a QAM demodulator, a generalized equalizer, and an enhanced Reed Solomon (RS) FEC decoder with dynamic deinterleaving.

The AFE performs analog-to-digital conversion (ADC) on RF input (either at 164 MHz or 204 MHz). The BCM3142 incorporates unique word detections of programmable length and pattern in the burst preamble for signal acquisition as fast as 16 symbols. An adaptive equalizer and ingress canceller of BCM3142 characterizes the RF channel response, cancels ingress noise, and removes intersymbol interference (ISI) caused by microreflections in the channel. The FEC decoder consists of a programmable derandomizer, a programmable RS decoder with T values programmable up to 16, and a byte deinterleaver with burst-by-burst reconfiguration capability.