MC13202 Technical Data, Rev. 1.4

24

Freescale Semiconductor

9.1.2

Dual Port Operation

A second set of pins designated PAO_P and PAO_N allow operation in a dual port configuration. There

are separate paths for transmit and receive with the optional CT_Bias pin providing a signal that indicates

if the radio is in TX or RX Mode which then can be used to drive an external low noise amplifier, power

amplifier, or antenna switch.

In dual port operation, the RFIN_P and RFIN_N are inputs only, the internal RX switch to the LNA is

enabled to receive, and the associated TX PA stays disabled. Pins PAO_P and PAO_N become the

differential output pins and the associated TX PA is enabled for transmit.

Figure 14 shows two dual port configurations. First is a single antenna configuration with an external low

noise amplifier (LNA) for greater range. An external antenna switch is used to multiplex the antenna

between receive and transmit. An LNA is in the receive path to add gain for greater receive sensitivity.

Two external baluns are required to convert the single-ended antenna switch signals to the differential

signals required by the radio. Separate RFIN and PAO signals are provided for connection with the baluns,

and the CT_bias signal is programmed to provide the external switch control. The polarity of the external

switch control is selectable.

Figure 14 also shows a dual antenna configuration where there is a RX antenna and a TX antenna. For the

receive side, the RX antenna is ac-coupled to the differential RFIN inputs and these capacitors along with

inductor L1 form a matching network. Inductors L2 and L3 are ac-coupled to ground to form a frequency

trap. For the transmit side, the TX antenna is connected to the differential PAO outputs, and inductors L4

and L5 provide DC-biasing to VDDA but are ac-isolated. CT_Bias is not required or used.