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3.4. Square-Wave Direct Tie Type Matching Network Layout Based on the4463-PSQ20D169 (4463CPSQ20D169) Pico Board (Single Antenna without RFSwitch)For reference, layout examples shown in this section are based on the layout of the 4463-PSQ20D169(4463CPSQ20D169) RF Pico Boards. These boards contain one antenna, and the TX and RX paths areconnected directly together without the use of an RF switch.The schematic of the SQW Direct Tie type matching network for the Si446x is shown in Figure 18.During TX mode operation, the built-in LNA protection circuit turns on (see “AN648: Si4063/Si4463/64/68) TXMatching” for more details). In this case, the dc path from the output of the matching network to the GND is notblocked through the RX side, so a dc blocking capacitor (CC1) is necessary.In the case of Direct Tie type matching, the coupling between the RX and TX sides is not critical since no harmonicleakage through the coupled RX path occurs since both of them are filtered after the common connection point
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