RF5565 Datasheet, PDF (11/14 Pages) RF Micro Devices – 2.4GHz TO 2.5GHz, 802.11b/g/n WiFi FRONT END MODULE

RF5565
Bypass Mode for WiFi Receive Operation
• Connect the RF input (ANT/pin-10) to a signal generator and a spectrum analyzer at the RX output. A multiport VNA may be
used as well.
• Set LNA_EN low. By applying a voltage <0.2V to this pin it enables the bypass switch of the LNA.
• Set C_RX high. This turns the receive branch of the SP3T ON.
• The SP3T controls for the off branches (C_TX and C_BT) must be set to a logic “low” (0.2V max) or grounded. In the event
that one of these branches is left floating or in a logic “high” the performance will degrade. It is recommended to terminate
unused RF Ports in 50Ω.
• Turn RF ON.
BLUETOOTH^® MODE
The RF765 Bluetooth^® only mode is implemented through the SP3T switch by setting C_BT “high.” Typical insertion loss is
about 1dB.
Bluetooth^® Biasing Instructions
• Connect the RF input (ANT/pin-10) to a signal generator and a spectrum analyzer at the BT (pin-8) RF port. A VNA may be
used in place of the Sig Gen and SA.
• Set C_BT “high.” This turns the Bluetooth^® branch of the SP3T switch ON.
• The SP3T controls for the off branches (C_TX and C_RX) must be set to a logic “low” (0.2V max) or grounded. Do not leave
floating.
• Terminate unused RF Ports in 50Ω
• Turn RF ON.
APPLICATION CIRCUIT AND LAYOUT RECOMMENDATIONS
The RF5565 integrates the matching networks and DC blocking capacitors for all RF ports. This greatly reduces the number of
external components and layout area needed to implement this FEM. Typically only a total of four external components are
required to achieve nominal performance. However, depending on board layout and the many noise signals that could poten-
tially couple to the RF5565, additional bypassing capacitors may be required to properly filter out unwanted signals that might
degrade performance.
The LNA bias components consist of an inductor and a decoupling capacitor. The inductor value is critical to optimize NF and
return loss at the RX output. For best performance and trade off between critical parameters such as NF, Gain, and IP3, the
total inductance including board trace should be approximately 1.2nH. The last components needed in the application circuit
are low frequency bypass capacitors on the VCC line. In general, it is good RF practice to have proper decoupling of supply lines
to filter noise out. Occasionally, depending on the level of coupling or parasitics of the board, a high frequency bypass capacitor
must be added as well.
In order to optimize performance for both the Transmit and Receive paths, best known RF practices for PCB layout must be fol-
lowed. All RF traces must be 50Ω. Adequate grounding along the RF traces and on the FEM ground slug must be exercised.
This will minimize coupling and provide good thermal dissipation when the PA is operating at high power. For reference, RFMD
evaluation board gerbers are available upon request.
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