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8. WLAN Radio Subsystem
The CYW43903 includes an integrated WLAN RF transceiver that has been optimized for use in 2.4 GHz Wireless LAN systems. It
has been designed to provide low-power, low-cost, and robust communications for applications operating in the globally available 2.4
GHz unlicensed ISM band. The transmit and receive sections include all on-chip filtering, mixing, and gain control functions.
Ten RF control signals are available to drive external RF switches. See the reference board schematics for more information.
A block diagram of the radio subsystem is shown in
differential transmit and receive paths to single-ended signal pins.
8.1 Receiver Path
The CYW43903 has a wide dynamic range, direct conversion receiver that employs high-order on-chip channel filtering to ensure
reliable operation in the noisy 2.4 GHz ISM band.
8.2 Transmit Path
Baseband data is modulated and upconverted to the 2.4 GHz ISM band. Linear on-chip power amplifiers deliver high output powers
while meeting IEEE 802.11b/g/n specifications without the need for external PAs. When using the internal PA, which is required in the
2.4 GHz band, closed-loop output power control is completely integrated.
8.3 Calibration
The CYW43903 features dynamic and automatic on-chip calibration to continually compensate for temperature and process variations
across components. These calibration routines are performed periodically during the course of normal radio operation. Examples of
some of the automatic calibration algorithms are baseband filter calibration for optimum transmit and receive performance and LOFT
calibration for carrier leakage reduction. In addition, I/Q calibration and VCO calibration are performed on-chip. No per-board
calibration is required during manufacturing testing. This helps to minimize the test time and cost in large-volume production environ-
ments.
TX Mode
Switch
WL‐G‐LNA11
TX Mode
Switch
Document Number: 002-14826 Rev. *G
PRELIMINARY
Figure
10. Note that integrated on-chip baluns (not shown) convert the fully
The 2.4 GHz path has a dedicated on-chip low-noise amplifier (LNA).
Figure 10. Radio Functional Block Diagram
WL TX 2.4 GHz Mixer
WL PA
WL G‐LNA12
WL RX 2.4 GHz Mixer
WL 2.4 GHz TX
WL 2.4 GHz RX
WL TXLPF
WL TXLPF
WL RXLPF
WL RXLPF
WL LOGEN
WL PLL
LPO/Ext LPO/RCAL
CYW43903
WL DAC
WL DAC
Voltage
WLAN BB
Regulators
WL ADC
WL ADC
Shared XO
XON
XOP
Page 26 of 65
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