AN851 Datasheet, PDF (6/25 Pages) Silicon Laboratories – Si468X SCHEMATICS AND LAYOUT GUIDE

AN851
4. Antenna and Matching Network Design and Layout
4.1. HP Antenna (Si468x)
The Si468x Digital Radio Receiver component supports a headphone antenna interface through the VHFI pin. A
headphone antenna with a length of 1.1 m suits FM/FMHD/T-DMB/DAB applications well.
4.1.1. Headphone Antenna Design
A typical headphone cable will contain three or more conductors. The left and right audio channels are driven by a
headphone amplifier onto left and right audio conductors and the common audio conductor is used for the audio
return path and RF antenna. Additional conductors may be used for microphone audio, switching, or other
functions, and in some applications the RF antenna will be a separate conductor within the cable. A representation
of a typical application is shown in Figure 3.
Figure 3. A Typical HP Antenna Application
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