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.
FEATURES SUMMARY OF BENEFITS
Video O ut
Audio O ut
BCM3250
QAMLink
®

Advanced
Set-top Box
Single-Chip
Front-End
Dual
Tuner
with
Diplex
Filter
Video Channel
Upstream T ransmitter
Out-of-Band Channel
IP Data Channel
BCM7038 Dual HD decoder
MIPS64 microprocessor
Transport/Graphics Subsystem
Peripherals
Cable
Plant
Analog V ideo
I/O
CPU
V.90 S oft Modem
Codec