BCM3250
®
BCM3250 QAMLINK
®
ADVANCED SET-TOP BOX SINGLE-CHIP FRONT-END
FEATURES
SUMMARY OF BENEFITS
•
Two complete QAMLink variable symbol rate receivers (in-
•
•
•
•
•
•
Direct interface to VoIP DSP
band video and DOCSIS/EuroDOCSIS IP data receive
channels)
•
Dual 10-bit A/D converters with input AGC amplifiers
•
Dual 1-7 Mbaud 256-QAM receivers
•
Dual ITU-T J.83 Annex A/B/C compatible FEC decoders
QPSK out-of-band receiver
•
100 – 200 MHz LO with AGC and 6-bit A/D converter
•
DigiCipher II®/DVB/DAVIC FEC decoder
Upstream QPSK/16-QAM transmitter
•
0 – 65 MHz direct RF output
•
Programmable Starvue II/DOCSIS/EuroDOCSIS/DVB/DAVIC
FEC encoder
•
10-bit D/A converter with output power control interfaces
DOCSIS/EuroDOCSIS media access controller (MAC)
•
DOCSIS/EuroDOCSIS version 1.1 based
•
Extensions for fragmentation and concatenation
•
Support for enhanced Quality of Service (QoS) for Voice over
IP (VoIP) applications
DAVIC media access controller (MAC)
•
DAVIC 1.2/1.5 compliant
•
Support for 1.5 Mbps and 3 Mbps on both upstream and
downstream
•
Parsing, CRC, and ATM cell extraction
•
Hardware SAR engine
Both processor interface and PCI 2.2
•
Represents a complete solution for interactive set-top box
•
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front-end, including cable modem functions.
•
Universal front-end supports the ITU-T J.83 Annex A/B/C as
well as OpenCable, DOCSIS/EuroDOCSIS and DVB/DAVIC.
•
DOCSIS/EuroDOCSIS 1.1-based media access controller
(MAC) supports Voice over IP and high-speed Internet access
capability.
•
DAVIC 1.2/1.5 MAC supports conditional access systems and
lower data rate services.
•
BCM3250, together with BCM7020/BCM7030 Video Decoder
and Graphics Engine, provide a two-chipset solution for
OpenCable applications.
Includes second in-band channel pass through for picture-in-
picture functionality and multiple camera angles.
Integration of all analog functions leads to lower system cost
and improved performance.
Single upstream transmitter is shared between modem and
upstream interactive video commands, eliminating the need
for a second upstream channel.
Integrated peripheral control unit supports required set-top
box peripherals without additional external devices.
Interactive Set-Top Box System Block Diagram
Analog V
ideo
Cable
Plant
Dual
Tuner
with
Diplex
Filter
IP Data Channel
Video Channel
Out-of-Band Channel
BCM3250
QAMLink
®
Advanced
Set-top Box
Single-Chip
Front-End
BCM7038 Dual HD decoder
MIPS64 microprocessor
Transport/Graphics Subsystem
Peripherals
Video O
ut
Audio O
ut
Upstream T
ransmitter
CPU
V.90 S
oft
Modem
Codec
I/O
OVERVIEW
IRTx
IRRx
LEDC
KBDC
TXn
RXn
JTAG
JTAG
TUN_CTL
Tuner
Interface
IR Tx/Rx
Interface
LED
Interface
Variable
Interpolator
Keypad
Interface
Nyquist
DUART
JTAG
SPI
Master
PCI 2.2/
Microcontroller
Interface
Upstream
DAVIC 1.2/1.5
Tx
MAC
Address, Data, Control
0-65 MHz
10-Bit
D/A
DDS
Variable
Interpolator
Nyquist
Pre-
Equalizer
Starvue
ITU-T J.83
Annex B
DAVIC
FEC
POD I/F
External Input
to US Modulator
Variable
Interpolator
36/44 MHz
Nyquist
10-Bit
A/D
= .12-.18
DDS
Variable
Interpolator
1
Phase
Recovery
and
40-Tap
DFE
ITU-T J.83
Annex
A/B/C
FEC
DOCSIS
1.1
MAC
DMA
and
SDRAM
Controller
Direct Connection
to SDRAM
Acquisition and Tracking Loops
Variable
Interpolator
36/44 MHz
IB1 MPEG-2
Transport Stream
10-Bit
A/D
=
DDS
Variable
Interpolator
Phase
Recovery
and
40-Tap
DFE
ITU-T J.83
Annex
A/B/C
FEC
PID
Filter
IB2 MPEG-2
Transport Stream
IB/OB Acquisition and Tracking Loops
Variable
Interpolator
36/50 MHz
Nyquist
6-Bit
A/D
= .30-.50
DDS
Variable
Interpolator
Nyquist
= .30-.50
4-Tap
Equalizer
OOB
DCII
DAVIC
FEC
100-200 MHz
Agile PLL
DAVIC 1.2/1.5
RX MAC
and
Message
Processor
POD I/F
OOB
Output Stream
The Broadcom
BCM3250
combines dual 256-QAM receivers, a 4/16-
QAM burst transmitter, an out-of-band QPSK receiver, a DOCSIS/
EuroDOCSIS 1.1 based MAC, and a DAVIC 1.2/1.5 compliant MAC
integrated into a single chip. The
BCM3250
is the world’s first complete
front-end solution with an integrated DOCSIS/EuroDOCSIS 1.1 MAC
to address the next generation of OpenCable/interactive set-top boxes.
Quality of Service (QoS) and fragmentation are supported for additional
applications, such as telephony and high-speed Internet access.
The dual receivers in the
BCM3250
directly sample a 36–44 MHz
carrier frequency with a l0-bit A/D converter, which is preceded by a
programmable gain amplifier (PGA). Two distinct forward error
correction (FEC) methods are supported in each receiver. The first
standard, ITU-T J.83 Annex A/C, is also referred to as the DVB or
DAVIC standard. The second, ITU-T J.83 Annex B, is variously known
as DigiCipher II® and SCTE DVS-031.
The out-of-band (OOB) receiver in the
BCM3250
contains a frequency
agile oscillator that can down convert any channel in the 70–130 MHz
frequency range to a SAW centered IF. The desired channel is then sub-
sampled by a 6-bit A/D converter at a rate that is more than four times
the symbol rate. OOB data can be passed through or terminated by the
DAVIC MAC or message processor.
On the upstream channel, the
BCM3250
provides complete Starvue II,
Annex B, and DAVIC compatible 4/16-QAM upstream burst FEC
encoder and modulator functionality. In the final stage, an on-chip 10-
bit DAC converts the signal to an analog waveform with programmable
output power levels.
The DOCSIS/EuroDOCSIS 1.1 MAC includes baseline privacy
encryption and decryption, transmission convergence sublayer support,
a TDM/TDMA framer and a scatter/gather DMA interface. The MAC in
the
BCM3250
also includes fragmentation, concatenation, and multiple
SIDs, enabling full support for Quality of Service applications such as
Voice over IP.
The DAVIC 1.2/1.5 MAC enables the
BCM3250
to operate in DAVIC-
centric conditional access systems. It supports Extended Super Frame
(ESF) parsing on the downstream and upstream timing/synchronization.
Hardware also performs data filtering and SAR functions.
The
BCM3250
also provides a peripheral control unit consisting of a
keypad controller, LED controller, IR receiver and transmitter controller.
In addition, dual UARTs, a generic I/O port controller, an interrupt
controller, and an RF tuner controller are included.
The high level of integration of the
BCM3250
provides the lowest
system cost for the next generation of interactive set-top boxes. The
BCM3250,
along with the BCM7038, provides a complete interactive
set-top box solution with advanced graphics capabilities.
Broadcom
®
, the pulse logo, and
Connecting everything
®
are trademarks of Broadcom Corporation and/
or its subsidiaries in the United States and certain other countries. All other trademarks mentioned are the
property of their respective owners.
®
BROADCOM CORPORATION
16215 Alton Parkway, P.O. Box 57013
Irvine, California 92619-7013
© 2003 by BROADCOM CORPORATION. All rights reserved.
3250-PB10-R
12/29/03
Phone: 949-450-8700
Fax: 949-450-8710
E-mail: info@broadcom.com
Web: www.broadcom.com
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