User's Manual

Bluegiga Technologies Oy
Page 22 of 41
7 Wi-Fi radio
7.1 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 Global System for Mobile
Communications (GSM) and Wideband Code Division Multiple Access (W-CDMA) cellular phone transmitters
without being desensitized. High-order baseband filters ensure good performance against in-band
interference.
7.2 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 +16dBm
for IEEE 802.11b. The module internally compensates for PA gain and reference oscillator frequency drifts
with varying temperature and supply voltage.
7.3 Antenna switch for Bluetooth coexistence
WF111 supports sharing the integrated antenna or antenna connector with a Bluetooth device through the
BT_RF pad. The module contains a bypass switch to route the Bluetooth signal directly to the antenna, and
supports using the internal LNA for Bluetooth reception. The switch is controlled through the coexistence
interface. Using the switch will require either two extra control lines or support for Unity-3e scheme for both
devices.
Antenna sharing will require full re-certification of both modules used for FCC due to the changed antenna
path and some radiated emission measurements for CE. Without a combined stack driver, the coexistence
system will have reduced performance and antenna sharing will reduce it further during simultaneous
communication. The antenna switch will also have some losses which will reduce Bluetooth range. For low
rate communication or non-simultaneous use the system should function well.
Currently, Bluegiga does not recommend antenna sharing due to the suboptimal performance.