Features: • Downstream QAM receiver for international applications
• Integrated QAMLink receiver with Forward Error Correction (FEC)
• 1-7 MBaud variable symbol rate receiver
• Supports variable channelization
• Supports 4, 16, 32, 64, 128 and 256-QAM
• Digital demodulator, Nyquist filters, tracking loops,
and 20-tap adaptive decision feedback equalizer
• Digital derotator for wideband carrier phase tracking
• DVB/DAVIC-compliant FEC decoder
• Reed-Solomon (N,K) = 204,188: t=8
• Convolutional detinterleaver, I=1-12 with internal
RAM, I=204 with external RAM
• I2C or SPI-compatible microcontroller interface
• Integrated 10-bit analog-to-digital converter
• On-chip generation of all clock and control signals
• JTAG test interface
• 100-pin PQFP PackageDescriptionThe BCM3118B QAMLink DVB/DAVIC Receiver with FEC is an integrated digital transmission solution for cable modems, cable-TV set-top boxes and digital microwave radios. Its bandwidth-efficient feature set expands the existing potential bandwidth of a standard analog network and provides operators with reliable, error-free transmission. Optimized for highvolume manufacturing, the BCM3118B is a highly integrated solution that reduces the system-level chip count, the cost, and the complexity associated with manufacturing RF receivers.
A single-chip solution, the BCM3118B has a 10-bit A/D converter, a 256-QAM demodulator with square-root raisedcosine receive filters, an adaptive equalizer with an embedded phase recovery derotator, acquisition and tracking loops, and a DVB/DAVIC-compliant Reed-Solomon FEC decoder with deinterleaver. The demodulator supports QPSK, 16, 32, 64, 128 and 256-QAM formats and adapts to channels encoded at different data rates up to 56 Mbps. The equalizer in the BCM3118B achieves transmission performance within 1 dB of theory over worse-case channels with multipath delays as long as 2.4 microseconds at 5 MBaud or 1.7 microseconds at 7 MBaud and amplitudes within .5 dB of the desired signals. With this level of performance, the device combats the effects of channel distortions commonly found in cable-TV systems. The BCM3118B has an integrated A/D converter, which eliminates the costs associated with fine tuning of external components during high-volume production.
The BCM3118B samples the analog IF waveform being delivered to BCM3118B by the integrated A/D converter. The signal is then digitally mixed to baseband and filtered by dual square-root Nyquist filters. Inter-symbol interference is then removed by the adaptive decision feedback equalizer. Adecision slicer, which supports constellations up to 256-QAM, formats the equalized data. The data is then fed into a DVB/DAVICcompliant synchronization block, deinterleaver, Reed-Solomon FEC, and derandomizer. The final error-corrected output is delivered in an MPEG-2 transport format.
The BCM3118B can be used as a stand-alone chip or with Broadcom's BCM3250 for a complete watch and record solution with EuroDOCSIS. Compliant with the ITU-T J83/Annex A and Annex C, DVB/DAVIC and the IEEE802.14 cable transmission standards for QAM downstream, the BCM3118B is a universal ownstream solution for worldwide coaxial cable applications.
BCM3118B Data Sheet
