BCM4339 Preliminary Data Sheet
External Frequency Reference
Table 2: Crystal Oscillator and External Clock—Requirements and Performance (Cont.)
External Frequency
Referenceb c
Crystala
Parameter
Conditions/Notes
Min. Typ. Max. Min. Typ. Max. Units
WRF_XTAL_IN
input high level
DC-coupled digital signal
–
–
–
1.0
–
1.26
V
WRF_XTAL_IN
input voltage
AC-coupled analog signal
–
–
–
1000
–
1200 mVp-p
(see Figure 5)
Duty cycle
37.4 MHz clock
–
–
–
–
–
–
–
40
–
50
–
60
%
Phase noisef
37.4 MHz clock at 10 kHz offset –
37.4 MHz clock at 100 kHz offset –
–129 dBc/Hz
–136 dBc/Hz
–
–
(IEEE 802.11b/g)
Phase noisef
37.4 MHz clock at 10 kHz offset –
37.4 MHz clock at 100 kHz offset –
–
–
–
–
–
–
–
–
–137 dBc/Hz
–144 dBc/Hz
(IEEE 802.11a)
Phase noisef
37.4 MHz clock at 10 kHz offset –
37.4 MHz clock at 100 kHz offset –
–
–
–
–
–
–
–
–
–134 dBc/Hz
–141 dBc/Hz
(IEEE 802.11n,
2.4 GHz)
Phase noisef
37.4 MHz clock at 10 kHz offset –
37.4 MHz clock at 100 kHz offset –
–
–
–
–
–
–
–
–
–142 dBc/Hz
–149 dBc/Hz
(IEEE 802.11n,
5 GHz)
Phase noisef
37.4 MHz clock at 10 kHz offset –
37.4 MHz clock at 100 kHz offset –
–
–
–
–
–
–
–
–
–148 dBc/Hz
–155 dBc/Hz
(IEEE 802.11ac,
5 GHz)
a. (Crystal) Use WRF_XTAL_IN and WRF_XTAL_OUT.
b. See “External Frequency Reference” on page 31 for alternative connection methods.
c. For a clock reference other than 37.4 MHz, 20 × log10(f/37.4) dB should be added to the limits, where f = the
reference clock frequency in MHz.
d. The frequency step size is approximately 80 Hz.
e. It is the responsibility of the equipment designer to select oscillator components that comply with these
specifications.
f. Assumes that external clock has a flat phase-noise response above 100 kHz.
Broadcom®
November 17, 2014 • 4339-DS106-R
Page 32
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