BCM4356XKWBGT Datasheet, PDF (29/195 Pages) Cypress Semiconductor – Single-Chip 5G WiFi IEEE 802.11ac 2×2 MAC/ Baseband/Radio with Integrated Bluetooth 4.1, FM Receiver, and Wireless Charging

BCM4356 Advance 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 BCM4356 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 7. Consult the reference
schematics for the latest configuration.
Figure 7: Recommended Oscillator Configuration
C*
WRF_XTAL_IN
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 BCM4356 generates the radio frequencies, clocks, and data/packet timing,
enabling it to operate using a wide selection of frequency references.
For SDIO and PCIe WLAN host applications, the recommended default frequency reference is a 37.4 MHz
crystal. For PCIe applications, see Table 3 on page 29 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^®
May 8, 2015 • 4356-DS103-R
BROADCOM CONFIDENTIAL
Page 28