ADF5355 datasheet(29/38 Pages) AD

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Data Sheet

ADF5355

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:

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

IBLEED is the value of constant negative bleed applied to the

charge pump, which is set by the contents of Bits[DB20:DB13].

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

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.

RF Output B Enable

D7 (Bit DB10) enables or disables the high frequency RF output

(RFOUTB). If DB10 is set to 0, the auxiliary high frequency RF

output is enabled. If DB10 is set to 1, the auxiliary RF output is

disabled.

Reserved

Bits[DB9:DB7] are reserved and must be set to 000.

RF Output A Enable

D3 (Bit DB6) enables or disables the primary RF output

(RFOUTA+/RFOUTA−). If DB6 is set to 0, the primary RF output

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

Output Power

D2 and D1 (Bits[DB5:DB4]) set the value of the primary RF

output power level (see Figure 47).

Rev. A | Page 29 of 38

ADF5355 Datasheet(PDF) 29 Page - Analog Devices