AN851 Datasheet, PDF (19/25 Pages) Silicon Laboratories – Si468X SCHEMATICS AND LAYOUT GUIDE

APPENDIX B—GUIDE TO TUNE THE FRONT END
NETWORK
Analyzing the Front End
AN851
Figure 12. Antenna Interface with Module FE
Figure 12 shows the electrical model of telescopic antenna connected to the front end of the module via coax
cable. The telescopic antenna is electrically represented by a variable resistor and a variable capacitor. The
electrical representation of coax cable is capacitor to ground. The length of the cable becomes important to
consider when selecting the front end component values. The interface of antenna and cable with module front end
can be simplified into Norton equivalent as shown in Figure 14.
Figure 13. Antenna Interface with Module FE
Rev. 0.2
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