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RFFM5765Q

DS121126

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

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

WiFi and Bluetooth Receive (Simultaneous Mode)

The RFFM5765Q WiFi and Bluetooth receive circuits were specifically designed to address issues of simultaneous operation.

In this mode both signals can be received at the same time when the C_BWRX (pin-5) is set high. The typical gain for each RF

path is approximately 13dB and a NF of 3dB. During simultaneous mode the active components are the LNA, the SPST switch,

and only the Rx branch of the SP3T. Refer to the logic control table for proper settings.

Simultaneous Mode Biasing Instructions

• Connect the RF input (ANT/pin-10) to a signal generator and a spectrum analyzer at the Rx (pin-3) and BT (pin-8) RF ports. A multiport VNA

may be used as well.

• Turn the LNA bias ON (pin-4) and set the voltage to 3.3V.

• Set C_RX and C_BWRX high. This turns ON the receive branch of the SP3T and the SPST switch.

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 RFFM5765Q Bluetooth only mode is implemented through the SP3T switch by setting C_BT “high.” Typical insertion loss is

about 1.2dB.

Bluetooth Biasing Instructions

• Connect the RF input (ANT/pin-10) to a signal generator and a spectrum analyzer at the BT RF port. A VNA may be used in place of the Sig

Gen and SA.

• Set C_BT (pin-9) “high.” This turns the Bluetooth branch of the SP3T switch ON.

• Terminate unused RF Ports in 50Ω.

•Turn RF ON.

Application Circuit and Layout Recommendations

The RFFM5765Q integrates the matching networks and DC blocking capacitors for all RF ports. This greatly reduces the num-

ber 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

potentially couple to the RFFM5765Q, 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 5.6kΩ series resistor for the Bluetooth control line

helps to prevent unwanted signal from coupling to this pin. The resistor should be place as close as possible to the package

good RF practice to have proper decoupling of supply lines to filter out noise. 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, a good layout design must be implemented. In addi-

tion to designing 50

 RF lines, proper 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, the RFMD eval-

and control lines must be isolated from each other with ground vias in between them. RFMD evaluation board gerbers are

available upon request.