Data Sheet
Table Of Contents
- 1 Design guidelines
- 2 Ordering Information
- 3 Pinout and Terminal Descriptions
- 4 Packaging
- 5 Power control
- 6 Interfaces
- 7 Block diagram
- 8 Example schematics
- 9 802.11 Radio
- 10 Firmware
- 11 Host interfaces
- 12 Electrical characteristics
- 13 RF Characteristics
- 14 Physical dimensions
- 15 Layout guidelines
- 16 Soldering recommendations
- 17 Certifications
- 18 Qualified Antenna Types for WF121-E
Silicon Labs
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9 802.11 Radio
9.1 Wi-Fi Receiver
The receiver features direct conversion architecture. Sufficient out-of-band blocking specification at the Low
Noise Amplifier (LNA) input allows the receiver to be used in close proximity to GSM and WCDMA cellular
phone transmitters without being desensitized. High-order baseband filters ensure good performance against
in-band interference.
9.2 Wi-Fi Transmitter
The transmitter features a direct IQ modulator. Digital baseband transmit circuitry provides the required
spectral shaping and on-chip trims are used to reduce IQ modulator distortion. Transmitter gain can be
controlled on a per-packet basis, allowing the optimization of the transmit power as a function of modulation
scheme.
The internal Power Amplifier (PA) has a maximum output power of +15dBm for IEEE 802.11g/n and +17dBm
for IEEE 802.11b. The module internally compensates for PA gain and reference oscillator frequency drifts
with varying temperature and supply voltage.
9.3 Regulatory domains
WF121 uses the IEEE 802.11d standard to select the available channels based on the regulatory domain
setting of the access point, if enabled. If no domain information is available, WF121 will default to using FCC
channel list.