BCM43455 Preliminary Data Sheet
Frequency References
Section 3: Frequency References
An external crystal is used for generating all radio frequencies and normal operation clocking. As an alternative,
an external frequency reference may be used. In addition, a low-power oscillator (LPO) is provided for lower
power mode timing.
Crystal Interface and Clock Generation
The BCM43455 can use an external crystal to provide a frequency reference. The recommended configuration
for the crystal oscillator including all external components is shown in Figure 5. Consult the reference
schematics for the latest configuration.
Figure 5: Recommended Oscillator Configuration
C
WRF_XTAL_XOP
27 pF
37.4 MHz
C
x ohms
WRF_XTAL_XON
27 pF
Note: A reference schematic is available for further details.
Contact your Broadcom FAE.
A fractional-N synthesizer in the BCM43455 generates the radio frequencies, clocks, and data/packet timing,
enabling it to operate using a wide selection of frequency references.
The recommended default frequency reference is a 37.4 MHz crystal. The signal characteristics for the crystal
interface are listed in Table 2 on page 30.
Note: Although the fractional-N synthesizer can support alternative reference frequencies,
frequencies other than the default require support to be added in the driver, plus additional extensive
system testing. Contact Broadcom for further details.
Broadcom®
November 5, 2015 • 43455-DS109-R
Page 29
BROADCOM CONFIDENTIAL
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