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RF5565

DS120214

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.

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.

about 1dB.

• 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.

• 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.