博通BCM3142 QPSK/QAM突发接收方案

博通(Broadcom)公司的BCM3142是QAMLink®通用QPSK/QAM突发接收器,是高度集成的解决方案,能大大地降低解调器的板空间和成本,主要应用在数字有线调制解调器数据转发器中. BCM3142提供12个单独的有线网络接收器,能接收TDMA或SCDMA方案中的QPSK和m-QAM突发数据. BCM3142的主要特性包括模拟前端(AFE),SCDMA解扩,QAM解调器,通用的均衡器,以及增强的带动态去交织的Reed Solomon (RS) FEC译码器.本文介绍了BCM3142的主要特性,优势以及BCM3142 I/O 接口方框图和DOCSIS 3.0 有线调制解调器终端系统(CMTS)方框图.

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 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.

The BCM3142 delivers the recovered data stream and accepts receiver control inputs through an IP-based link DOCSIS MAC chip, such as the BCM3216. The BCM3142 prepends ranging and data information to each received code word and packet for processing by the BCM3216.

The BCM3142 is a highly integrated, mixed-signal, and cost-effective device providing a worldwide solution for burst receiver applications. The 12-receiver design of the BCM3142 is packaged in a 31x31 FCBGA with 1mm pitch, enabling a significant increase in upstream channel density for headend-based CMTS equipment. The BCM3142, combined with the BCM3040 QAMLink Universal Modulator and the BCM3216 Advanced QAMLink CMTS DOCSIS 3.0 MAC, provides a complete solution for advanced cable headend equipment.

主要特性:
The BCM3142 is a universal headend advanced TDMA and SCDMA physical
layer QPSK/QAM burst receiver.
DOCSIS® 3.0-based, IEEE 802.14™, DAVIC, and DVB compliant
Programmable demodulation including BPSK, QPSK, 8, 16, 32, 64, 128, and 256
QAM formats
Variable symbol rates from 160 KBaud to 5.12 MBaud, providing up to 40 Mbps
operation
Powerful Reed-Solomon FEC decoder with byte deinterleave options for
impulse/burst noise mitigation
Burst acquisition as fast as 16 preamble symbols
Four onchip analog-to-digital converters and four external serial interface
options
Direct sampling for DOCSIS via digital input operating either at 164 MHz or
204 MHz to support up to 85 MHz reverse path
Powerful equalization to provide ingress, ACI and inter-symbol interference
(ISI) protection
Integrated Fast Fourier Transform (FFT) processor with variable FFT sizes and
programmable window options
Dual gigabit Ethernet ports independently configurable to use either GMII or
SerDes
Broadcom serial control (BSC) or SPI-compatible microcontroller interface
65 nanometer process and JTAG test interface with AC-JTAG support for the
GMII and external ADC SerDes
Operates over commercial temperature range (0°C to +70°C)
Supports up to four logical channels for each channel
Flexible association of RF ports and digital receiver channels using a digital
switch
Impulse noise time stamping on empty channel/idle slots
优势:
Presents a high-performance, integrated solution for upstream demodulation in
cable-over-data, video, and telephony applications.
12 independent burst receivers per package enable high-density equipment
designs, reducing equipment board space requirements.
Based on DOCSIS 3.0 standards for use in cable modem termination systems
(CMTS).
Seamless integration with BCM3216 advanced CMTS DOCSIS 3.0 media
access controller (MAC).
Applies to digital CATV reverse-channel receiver.
High bps/Hz modulation enables advanced digital services over narrow RF
channels.
Direct sampling using high-speed ADCs minimizes RF components.
Use of onchip ADCs minimizes external components.
Onchip equalizer enables operation of digital services under challenging plant
conditions.
Onchip FFT and impulse noise time-stamping enable spectrum analysis and
management of the entire upstream channel.
Small footprint enables high-density equipment.



图1.BCM3142 I/O 接口方框图



图2.DOCSIS 3.0 有线调制解调器终端系统(CMTS)方框图