We have previously used the HMC625HFLP5E (now marked obsolete).
The alternative part HMC625ALP5E is mostly the same except for the addition of the ACG1 - ACG6 pins (where previously they were N/C).
The datasheet suggests these be connected to AGND with a capacitor to suit the lowest frequency of operation.
For an operating frequency of 5 to 6 GHz, are any capacitors required?
Is there anything else we need to consider before using the HMC625ALP5E as a drop in replacement?