Ldo Configurations - Analog Devices ADRV9005 Reference Manual

Reference Manual
POWER-SUPPLY RECOMMENDATIONS
Note: is a schematic notation to merge nets with different names. There is no real component here. The rest of the power supplies need
their own FB/cap filter network.
Implementing and testing this power solution shows no visible signs of RF performance degradation in phase noise or additional spurs, or any
other system level issues. Any noise on the power supplies inadvertently affects the RF output of the part. So, be cautious when designing a
power solution.

LDO CONFIGURATIONS

Note: Consider this section carefully. Failure to implement the LDO modes correctly can result in an incorrect voltage being applied and
potentially damage the RF circuits.
The VDDA_1P0 is a power domain that powers all the transmitter and receiver LO circuits. Power this domain using internal LDOs that
generate the 1 V needed from the 1.3 V supply. Alternatively, power it externally by bypassing some of the internal LDOs. Use this in cases
requiring power savings or with an already available 1 V supply in the system. Save some power by turning off the LDOs and applying a higher
efficiency external power source to the 1 V rails. The new 1 V external power domain is a low-noise supply with a tolerance of ±2.5%.
The LDO configurations on the ADRV9001 can affect the overall power consumption. On the ADRV9001 evaluation board, all the internal LDOs
are used and they generate the 1 V needed for all the rails. This allows for different RF channels while evaluating. In an end system, the user
knows what RF channels they are using and can tailor the RF channels to the system.
To implement an ideal LDO configuration for the end use case:
Use the application to determine how many transmitter, receiver, and LO channels are needed.
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Design a power supply to implement the determined use case.
►
Choose what LDO configuration is needed and set the LDO modes appropriately.
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APPLICATION POWER NEEDS
Deciding what LDOs to use/bypass depends on the transmitter, receiver, and LO combinations going to be used. For example, in the 1T/2R
FDD use case, do not use one of the transmit channels and then power down the internal LDOs for this channel. The
Configurations section provides details on how to wire the power domains.
The following board power supply configurations are supported.
analog.com
Figure 304. Merged LO Supplies
Figure 305
ADRV9001
shows three examples.
Power-Supply
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