BOARDCOM BCM2051 Highly linear receive path ensures robust, interference free operation Datasheet

BCM2051
PRODUCT
Brief
BCM2051
B C M 2 0 5 1
802.11B
F E AT U R E S
Zero IF, single-chip direct conversion radio integrates
• complete
802.11b RF and IF.
Fully integrated VCO minimizes external component
• count
and reduces overall BOM cost.
• Single 2.7V to 3.3V voltage supply.
Operation over extended temperature range provides
• robust
radio performance in integrated laptop and
embedded designs.
Highly linear receive path ensures robust, interference• free
operation.
Exceptional adjacent channel and out-of-band blocking
• mitigates
the effects of other wireless LAN, Bluetooth,
and microwave oven effects.
S U M M A R Y
RADIO
O F
B E N E F I T S
Monolithic implementation in a standard digital
• CMOS
process with minimal external components
provides a manufacturable low-cost 802.11b RF/IF
solution.
On-chip auto-calibration eliminates process variation
• across
components and mitigates temperature
variation, enabling it to be used in high-volume
applications.
Performance is optimized to ensure the robust
• performance
in real-world operating environments.
Low power consumption enables integration into low• power
wireless solutions.
Minimum external BOM provides the lowest cost
• solution
for 802.11b radio solutions.
802.11b Application
Balun
BCM2051
802.11b
Radio
Diversity
Switch &
BPF
T/R
Switch
Power
Amp
Balun
Crystal
BROADCOM PROPRIETARY & CONFIDENTIAL
BCM4301
802.11b
MAC & BB
System
Interface
B C M 2 0 5 1
O V E R V I E W
BCM2051 802.11b Radio
Automatic
Calibration
Control
Control and
Data Interface
I/Q Output
RF Input
LO
Generation
RF Output
The BCM2051 802.11b zero IF Radio is an integrated
transceiver device that has been optimized for use in 2.4-GHz
802.11b wireless systems. It has been designed to provide lowpower, low-cost, and robust communications for applications
operating in the globally available 2.4-GHz unlicensed ISM
band. It is fully compliant with the 802.11b specification and
meets or exceeds the requirements where appropriate to provide
the highest communication link quality of service.
The BCM2051 features a simple, innovative shared LO
architecture that allows a high-performance radio implementation
in a single CMOS chip. A proprietary PLL design generates
quadrature LO signals in the 2.4-GHz band for both the transmitter
and receiver. The PLL is locked to a 12-MHz free running crystal
oscillator. A proprietary self-calibrating VCO is fully integrated
and does not require external VCO or tank circuits. This creates a
frequency agile LO, ensures the lowest phase noise performance
and covers the full 2.4-GHz ISM band.
The receiver front end consists a low noise amplifier, a single
side band mixer and on-chip low pass filter, which provide good
performance without a costly external IF band pass filter.
Because the entire receive channel is one chip, all sensitive
components are eliminated from the board design and this leads
to the most robust and noise-immune design, optimal for
integration in laptop computers and embedded applications.
PLL
Frac N
I/Q Input
An overall noise figure of 6 dB is achieved along with 85-dB gain
which can acheive -84-dBm sensitivity for 11-Mbps CCK
modulation.
The internal lowpass filter structure also features DC
cancellation loop and self-calibration circuitry, which
automatically adjusts circuit elements to compensate for any
process variation. This eliminates tuning and ensures that the
devices are uniform across process variation and temperature. An
RSSI signal is also generated in these amplifiers for the system
to determine signal strength. The output is a stable I/Q output for
direct interface to the BCM430X series of baseband/MAC
components.
The transmit signal is input through the I/Q input from the
baseband. It is then filtered and upconverted to RF using the
quadrature LO signals. The signal is then boosted to a minimum
1-mW output power level by an internal power amplifier. The
output signal is optimized to enable easy integration with widely
available power amplifiers and minimizes the linearity
requirements for these devices. Output power control is digitally
programmable from full power to low power in 4-dB steps.
The BCM2051 is controlled directly from the baseband and MAC
through a fully digital control interface. This interface provides
control for the various sections of the chip, defines data transfers
and allows access to the various internal registers of the device.
The BCM2051 is in a 64-pin LPCC package.
Broadcom® and the pulse logo® are trademarks of Broadcom Corporation
and/or its subsidiaries in the United States and certain other countries.
All other trademarks are the property of their respective owners.
For more information please contact us at:
Phone: 949-450-8700, FAX: 949-450-8710
Email: [email protected]
BROADCOM CORPORATION
16215 Alton Parkway, P.O. Box 57013
Irvine, California 92619-7013
BROADCOM PROPRIETARY & CONFIDENTIAL
Visit our web site at: www.broadcom.com
© 2001 by BROADCOM CORPORATION. All rights reserved.
2051-PB00-R-11.7.01
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