ADF4382ABCCZ datasheet(39/82 Pages) AD

39 / 82 page

Data Sheet

ADF4382A

APPLICATIONS INFORMATION

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Rev. A | 39 of 82

PHASE RESYNCHRONIZATION

Phase resynchronization is a feature that allows a consistent phase

on the RFOUT signal with respect to the input reference at each

output frequency, which is useful in applications requiring synchro-

nization of multiple ADF4382A devices. After multiple devices are

synchronized, any additional resynchronizing (for example, after a

frequency change) is not needed. When phase resynchronization

is used, the maximum value for MOD2WORDMAX is = 217 − 1 =

131071. Refer to Output Frequency section for MOD2WORDMAX

calculation

The following sequence is the phase resynchronization method

procedure:

1. Power up and initialize the ADF4382A devices.

2. Program all ADF4382A devices to the same frequency.

3. Perform an initial synchronization (timed synchronization or

EZSync).

4. Enable phase resynchronization mode by taking the following

steps:

a. Set DEL_MODE (Register 0x032, Bit 5) = 1.

b. Set EN_PHASE_RESYNC (Register 0x01E, Bit 7) = 1.

c. Set EN_REF_RST Register 0x01E , Bit 6) = 1.

d. Set EN_DRCLK (Register 0x02D, Bit 6) = 1.

e. Program the tRESYNC default to 100 μs by

tRESYNC= RESYNC_WAIT

fPFD

(53)

for fPFD = 250 MHz and tRESYNC = 25,000.

Note that when using fast power-up and initialization, manually

programmed VCO calibration settings mode, MUTE_NCLK must be

set to 1 when going from integer to fractional RF output frequencies

(or vice versa). In this case, phase resynchronization is maintained

each time MUTE_NCLK is set to 1 for a frequency change.

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