Semtech LR1121 - RF Switch Implementation; Figure 9-14: RF Switch, Double PA Operation; Figure 9-15: RF Switch, Single PA Operation (High Power PA Example)

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
97 of 130
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9.4.2 RF Switch Implementation
The implementation examples hereafter show a combined high power PA and high efficiency PA operation, with the use
of a 3-port RF switch SP3T. A single-band operation is also possible, the unused PA pin being left unconnected. In that case
a 2-port RF switch SPDT would be necessary.
The RF switch implementation optimizes the impedance presented to the PA and the impedance presented to the LNA
separately. Therefore one can optimize TX efficiency without compromising RX sensitivity.
The RF switch can be controlled either by the host controller, or by the LR1121 itself (pins DIO5, DIO6, DIO7, DIO8 and
DIO10), using the SetDioAsRfSwitch(...) command.
Figure 9-14: RF Switch, Double PA Operation Figure 9-15: RF Switch, Single PA Operation (High
Power PA Example)
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