42.8.1 Transmit Mixer and Power Amplifier
The PIC32CX-BZ2 and WBZ45 implement a direct conversion I/Q transmitter. The I/Q from the low pass filter of the TX path is converted to the desired output frequency through an I/Q mixer that operates on the LO frequency from the Synthesizer. The VCO operates at 4x the LO frequency.
The supply for LPA and MPA is through separated power supply pins that can be connected to the output from the PMU with necessary decoupling.
The LPA is a single stage amplifier that provides ~5.5 dBm output power in standalone mode and ~4 dBm in LPA/MPA shared mode. Both LPA and MPA implement an on-chip BALUN. The LPA pin also acts as the input to the RX section.
The MPA is a single stage power amplifier designed to provide a maximum output power of ~12 dBm. MPA also implements an on-chip BALUN to get a single-ended TX output. MPA is NOT internally connected to the receiver.It is mandatory that the LPA pin be used for the Receiver path. On a typical application, the LPA and MPA can be connected directly, eliminating the need for an external switch.
Note: For WBZ451H, the 48-pin QFN LPA/MPA is combined with the external FEM design to achieve +20 dBm output power. The WBZ451H module has the matching network for doing a combined match of the LPA and MPA path along with a harmonic filter followed by an antenna-matching circuit and an antenna.