ADF4382ABCCZ datasheet(31/82 Pages) AD

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Data Sheet

ADF4382A

THEORY OF OPERATION

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Rev. A | 31 of 82

DELSTR is an active high signal that is used to assert a phase

adjustment. The amount by which the phase is adjusted is set in

PHASE_ADJUSTMENT. The phase is adjusted on the falling edge

of the signal.

DELADJ is an active high signal that controls the direction of the

adjustment. If the signal is set to 0 while DELSTR is high, the

RFOUT signal phase adjusts to earlier in time relative to the initial

phase. If the signal is set to 1 while DELSTR is high, the RF output

signal advances in time relative to the initial phase.

Figure 56. DELSTR and DELADJ Timing Diagrams

RF Output Buffer

The low noise, differential output buffer in Figure 57 produces a

differential output voltage. The output amplitude level and common-

mode voltage is programmable with the RFOUT1_OPWR (Register

0x029, Bits[3:0]) and RFOUT2_OPWR (Register 0x029, Bits[7:4])

bits. Each output can be either AC- or DC-coupled and terminated

with 100 Ω differentially. If a single-ended output is desired, each

side of the output must be individually AC-coupled and terminated

with 50 Ω. External inductors are required to achieve the highest

output power. A 1.4 nH, 0402 sized, pull-up inductor is required

to be connected to the RFOUTx 3.3 V supply (V3_RFOUTx) from

the RFOUTx pins. Additionally, a series 100 nF capacitor must be

connected to the RFOUTx pins as shown in Figure 58.

Figure 57. Simplified RF Output Buffer Schematic

Figure 58. RFOUT Interface Schematic

Mute RF Output

The RFOUTxP and RFOUTxN pins can be muted by using the

MUTE_RFOUTx bit fields (Register 0x40, Bits[5:3] and Bits[2:0],

respectively.

Table 23. MUTE_RFOUTx, Bit 0 through Bit 7, Controls

MUTE_RFOUTx, Bits

Function

Normal operation

Mute low and disable the emitter follower driver

Mute high and disable the emitter follower driver

Mute low and leave the emitter follower driver on

Mute low and disable the emitter follower driver during

calibration

Mute low and keep the emitter follower running during

calibration

Mute low and disable the emitter follower driver when

LOCKED = 0

Mute low and keep the emitter follower running when

LOCKED = 0

It is recommended to use options that keep the emitter follower on

to minimize current fluctuations.

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