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Frequency References

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 27

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

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.

WRF_XTAL_OUT

WRF_XTAL_IN

Xohms*

*Valuesdeterminedbycrystal

drivelevel. Seereference

schematicsfor details.

37.4MHz

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