MC13202_08 Datasheet, PDF (23/30 Pages) Freescale Semiconductor, Inc – 2.4 GHz Low Power Transceiver for the IEEE 802.15.4 Standard

2 ^{RFIN_P (PAO_P)}
1 RFIN_M (PAO_M)
3 CT_Bias
5
PAO_P
6
PAO_M
PA1
RX
SW ITCH
LNA
PA2
RX ENABLE
PA2 ENABLE
CT_Bias Generator
CT_Bias CONTROL
FROM TX PSM
PA1 ENABLE
RX
SIGNAL
Figure 12. RF Interface Pins
9.1.1 Single Port Operation
The integrated RF switch allows users to operate in a single port configuration. In Single Port Mode, an
internal RX switch and separate PA are used and pins RFIN_P (PAO_P) and RFIN_M (PAO_M) become
bidirectional and connect both for TX and RX. When receiving, the RX switch is enabled to the internal
LNA and the TX PA is disabled. When transmitting, the RX switch is disabled (isolating the LNA) and a
TX PA is enabled. The optional CT_Bias pin provides a reference or bias voltage which is at VDDA for
transmit and is at ground for receive. This signal can be used to provide the proper bias voltage to a balun
that converts a single-ended antenna to the differential interface required by the transceiver.
Figure 13 shows a single port example with a balun.
MC13202/03
Balun
Bypass
RFIN_P (PAO_P)
L1
RFIN_M (PAO_M)
CT_Bias
PAO_P
PAO_M
Figure 13. Single Port RF Operation with a Balun
The CT_Bias is connected to the balun center-tap providing the proper DC bias voltage to the balun
depending on RX or TX.
MC13202 Technical Data, Rev. 1.4
Freescale Semiconductor
23