BCM3250
BCM3250 QAMLINK
ADVANCED SET-TOP BOX SINGLE-CHIP FRONT-END
Interactive Set-Top Box System Block Diagram
Two complete QAMLink variable symbol rate receivers (in-
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
Direct interface to VoIP DSP
Represents a complete solution for interactive set-top box
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.
F E A T U R E S
S U M M A R Y O F B E N E F I T S
V
ideo O ut
A
udio O ut
BCM3250
QAMLink
Advanced
Set-top Box
Single-Chip
Front-End
I/O
D
ual
T
uner
with
D
iplex
F
ilter
V
ideo Channel
U
pstream T ransmitter
O
ut-of-Band Channel
IP D
ata Channel
BCM7038 Dual HD decoder
MIPS64 microprocessor
Transport/Graphics Subsystem
Peripherals
C
able
P
lant
A
nalog V ideo
CPU
V.90 S
oft Modem
C
odec
O V E R V I E W
Phone: 949-450-8700
Fax: 949-450-8710
E-mail: info@broadcom.com
Web: www.broadcom.com
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
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.
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 3644 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 70130 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.
Tuner
Interface
IR Tx/Rx
Interface
DDS
DDS
DDS
DDS
LED
Interface
Keypad
Interface
JTAG
PCI 2.2/
Microcontroller
Interface
Upstream
DAVIC 1.2/1.5
Tx
MAC
DOCSIS
1.1
MAC
DMA
and
SDRAM
Controller
DUART
Starvue
ITU-T J.83
Annex B
DAVIC
FEC
PID
Filter
ITU-T J.83
Annex
A/B/C
FEC
ITU-T J.83
Annex
A/B/C
FEC
OOB
DCII
DAVIC
FEC
DAVIC 1.2/1.5
RX MAC
and
Message
Processor
POD I/F
POD I/F
Pre-
Equalizer
Phase
Recovery
and
40-Tap
DFE
Phase
Recovery
and
40-Tap
DFE
4-Tap
Equalizer
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Variable
Interpolator
Acquisition and Tracking Loops
IB/OB Acquisition and Tracking Loops
10-Bit
D/A
10-Bit
A/D
10-Bit
A/D
6-Bit
A/D
Agile PLL
TXn
RXn
KBDC
LEDC
IRTx
IRRx
JTAG
SPI
Master
JTAG
36/44 MHz
Address, Data, Control
External Input
to US Modulator
Direct Connection
to SDRAM
IB1 MPEG-2
Transport Stream
IB2 MPEG-2
Transport Stream
OOB
Output Stream
TUN_CTL
0-65 MHz
36/50 MHz
100-200 MHz
36/44 MHz
Nyquist
Nyquist
Nyquist
= .30-.50
Nyquist
= .30-.50
Nyquist
= .12-.18
1
=
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