BCM3250 Datasheet, PDF (2/2 Pages) Broadcom Corporation. – QAMLINK ADVANCED SER-TOP BOX SINGLE-CHIP FRONT-END

OVERVIEW
TUN_CTL
0-65 MHz
Tuner
Interface
IRTx IRRx
IR Tx/Rx
Interface
10-Bit
D/A
DDS
LEDC
LED
Interface
Variable
Interpolator
Variable
Interpolator
KBDC
Keypad
Interface
Nyquist
Nyquist
TXn RXn JTAG
JTAG
DUART
Pre-
Equalizer
JTAG SPI
Master
PCI 2.2/
Microcontroller
Interface
Starvue
ITU-T J.83
Annex B
DAVIC
FEC
Upstream
DAVIC 1.2/1.5
Tx
MAC
POD I/F
Address, Data, Control
External Input
to US Modulator
36/44 MHz
10-Bit
A/D
36/44 MHz
10-Bit
A/D
36/50 MHz
100-200 MHz
6-Bit
A/D
Agile PLL
DDS
Variable
Interpolator
Variable
Interpolator
Nyquist
= .12-.18
1
Phase
Recovery
and
40-Tap
DFE
DDS
Acquisition and Tracking Loops
Variable
Interpolator
=
Variable
Interpolator
Phase
Recovery
and
40-Tap
DFE
DDS
IB/OB Acquisition and Tracking Loops
Variable
Interpolator
Variable
Interpolator
Nyquist
= .30-.50
Nyquist
= .30-.50
4-Tap
Equalizer
ITU-T J.83
Annex
A/B/C
FEC
DOCSIS
1.1
MAC
ITU-T J.83
Annex
A/B/C
FEC
PID
Filter
OOB
DCII
DAVIC
FEC
DAVIC 1.2/1.5
RX MAC
and
Message
Processor
DMA
and
SDRAM
Controller
POD I/F
Direct Connection
to SDRAM
IB1 MPEG-2
Transport Stream
IB2 MPEG-2
Transport Stream
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.
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®
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: [phone]
Fax: [phone]
E-mail: [e-mail]
Web: www.broadcom.com