ADF4355BCPZ datasheet(26/36 Pages) AD

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Data Sheet

ADF4355

Rev. A | Page 25 of 35

Charge Pump Bleed Current

BL8 to BL1 (Bits[DB20:DB13]) control the level of the bleed

current added to the charge pump output. This current

optimizes the phase noise and spurious levels from the device.

Tests have shown that the optimal bleed set is the following:

4/N < IBLEED/ICP < 10/N

where:

IBLEED is the value of constant negative bleed applied to the

charge pump, which is set by the contents of Bits[BL8:BL1].

ICP is the value of charge pump current setting, Bits[DB13:DB10] of

N is the value of the feedback counter from the VCO to the PFD.

Reserved

Bit DB12 is reserved and must be set to 0.

Mute Till Lock Detect

When D8 (Bit DB11) is set to 1, the supply current to the RF

output stage is shut down until the device achieves lock, as

determined by the digital lock detect circuitry.

Reserved

Bit DB10 is reserved and must be set to 0.

Auxiliary RF Output Enable

Bit DB9 enables or disables the auxiliary frequency RF output

(RFOUTB+/RFOUTB−). When DB9 is set to 1, the auxiliary

frequency RF output is enabled. When DB9 is set to 0, the

auxiliary RF output is disabled.

Auxiliary RF Output Power

Bits[DB8:DB7] set the value of the auxiliary RF output power

level (see Figure 36).

RF Output Enable

Bit DB6 enables or disables the primary RF output (RFOUTA+/

RFOUTA−). When DB6 is set to 0, the primary RF output is

disabled. When DB6 is set to 1, the primary RF output is

enabled.

Output Power

Bits[DB5:DB4] set the value of the primary RF output power

level (see Figure 36).

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