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External Frequency Reference

BCM4354 Data Sheet

BROADCOM CONFIDENTIAL

Broadcom®

October 15, 2014 • 4354-DS109-R

Page 29

Drive level

External crystal must be able to

tolerate this drive level.

200

–

––––µW

Input impedance

(WRF_XTAL_IN)

Resistive

–

100

–

kΩ

Capacitive

––

7.5

––7.5

WRF_XTAL_IN

Input low level

DC-coupled digital signal

––

–0–0.2

WRF_XTAL_IN

Input high level

DC-coupled digital signal

–

1.0

–

1.26

WRF_XTAL_IN

input voltage

(see Figure 5)

AC-coupled analog signal

–

400

–

1200 mVp-p

Duty cycle

37.4 MHz clock

–

Phase Noiseg

(IEEE 802.11b/g)

37.4 MHz clock at 10 kHz offset –

–

–129 dBc/Hz

37.4 MHz clock at 100 kHz offset –

–

–136 dBc/Hz

Phase Noiseg

(IEEE 802.11a)

37.4 MHz clock at 10 kHz offset –

–

–137 dBc/Hz

37.4 MHz clock at 100 kHz offset –

–

–144 dBc/Hz

Phase Noiseg

(IEEE 802.11n,

2.4 GHz)

37.4 MHz clock at 10 kHz offset –

–

–134 dBc/Hz

37.4 MHz clock at 100 kHz offset –

–

–141 dBc/Hz

Phase Noiseg,h

(IEEE 802.11n,

5GHz)

37.4 MHz clock at 10 kHz offset –

–

–142 dBc/Hz

37.4 MHz clock at 100 kHz offset –

–

–149 dBc/Hz

Phase Noiseg

(IEEE 802.11ac,

5GHz)

37.4 MHz clock at 10 kHz offset –

–

–150 dBc/Hz

37.4 MHz clock at 100 kHz offset –

–

–157 dBc/Hz

a. (Crystal) Use WRF_XTAL_IN and WRF_XTAL_OUT.

b. See “External Frequency Reference” on page 28 for alternate 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. BT_TM6 should be tied low for a 52 MHz clock reference. For other frequencies, BT_TM6 should be tied high.

Note that 52 MHz is not an auto–detected frequency using the LPO clock.

e. The frequency step size is approximately 80 Hz resolution.

f. It is the responsibility of the equipment designer to select oscillator components that comply with these

specifications.

g. Assumes that external clock has a flat phase noise response above 100 kHz.

h. If the reference clock frequency is <35 MHz the phase noise requirements must be tightened by an additional

2dB.

Table 3: Crystal Oscillator and External Clock —Requirements and Performance (Cont.)

Parameter

Conditions/Notes

Crystala

External Frequency

Referenceb,c

Min.

Typ.

Max.

Min.

Typ.

Max.

Units

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