AN851 Datasheet, PDF (8/25 Pages) Silicon Laboratories – Si468X SCHEMATICS AND LAYOUT GUIDE

AN851
As shown in Figure 5, optional RF shunt capacitors C2 and C3 may be placed on the left and right audio traces at
the headphone amplifier output to reduce the level of digital noise passed to the antenna. The recommended value
is 100 pF or greater, however, the designer should confirm that the headphone amplifier is capable of driving the
selected shunt capacitance.
Table 2. Headphone Antenna BOM
Ref Designator
L1
L2
C13
Description
IND, SM, 100 nH, MURATA
IND, SM, 36 nH, MURATA
AC coupling cap, SM,
18 pF, Murata
Note
F1, F2, F3
D1, D2, D3
FERRITE BEAD, SM, 0603,
2.5 k, Murata,
BLM18BD252SNID
IC, SM, ESD DIODE,
SOT23-3, California Micro
Devices, CM1213
Table 3. Headphone Antenna Optional BOM
Ref Designator
C2
C3
Description
SM, 0402, X7R, 100 pF
SM, 0402, X7R, 100 pF
Note
Optional RF shunt capacitor
Optional RF shunt capacitor
8
Rev. 0.2