The transmitter impedance matching/filtering can be split into 3 sections: the impedance matching stage, the second harmonic filtering stage, and the higher order harmonic filtering stage.As shown in Figure 15, the chosen matching topology consists of L3 and C5, the second order harmonic filter consists of L3 and C4, and the higher order harmonic filter consisting of C5, L4 and C7. C6 serves as a DC block to protect the input of the RF switch. The expected input impedance to the RF switch is 50 ohms. The network at the output of the RF switch is primarily there to offer optimal matching to the antenna, but additional filtering can also be achieved through such network.