BCM4354 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 BCM4354 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 4. Consult the reference
schematics for the latest configuration.
Figure 4: Recommended Oscillator Configuration
C*
WRF_XTAL_I N
37.4 MHz
C*
X ohms*
WRF_XTAL_OUT
* Values determined by crystal
drive level. See reference
schematics for details.
A fractional-N synthesizer in the BCM4354 generates the radio frequencies, clocks, and data/packet timing,
enabling it to operate using a wide selection of frequency references.
For SDIO, HSIC, and PCIe WLAN host applications, the recommended default frequency reference is a 37.4
MHz crystal. For PCIe applications, see Table 3 on page 28 for details on alternatives for the external frequency
reference. The signal characteristics for the crystal oscillator interface are also listed in Table 3.
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®
October 15, 2014 • 4354-DS109-R
Page 27
BROADCOM CONFIDENTIAL
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