PRELIMINARY
CYW54907
8. WLAN Radio Subsystem
The CYW54907 includes an integrated dual-band WLAN RF transceiver that has been optimized for use in 2.4 GHz and 5 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 or 5 GHz U-NII bands. 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. In addition, these control signals can be used to support optional
external 5 GHz band power and low-noise amplifiers. See the reference board schematics for more information.
A block diagram of the radio subsystem is shown in Figure 13. Note that integrated on-chip baluns (not shown) convert the fully
differential transmit and receive paths to single-ended signal pins.
8.1 Receiver Path
The CYW54907 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 or the entire 5 GHz U-NII band. The 2.4 GHz and 5 GHz paths each have a dedicated
on-chip low-noise amplifier (LNA).
8.2 Transmit Path
Baseband data is modulated and upconverted to the 2.4 GHz ISM or 5 GHz U-NII bands, respectively. Linear on-chip power amplifiers
deliver high output powers while meeting IEEE 802.11a/b/g/n/ac specifications without the need for external PAs. When using the
internal PA, which is required in the 2.4 GHz band and optional in the 5 GHz band, closed-loop output power control is completely
integrated.
8.3 Calibration
The CYW54907 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
environments.
Document Number: 002-19312 Rev. *C
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