As we knew, ADL5385/5387 LO will be divide by 2 inside the chips, so I guess the local harmonic components do no harm to the mod/demod.
Am I right? If so, then we do not need insert a LPF between the loca oscillator and those chips.
You do not need a harmonic filter when driving 2XLO based IQ modulators and demodulators such as ADL5385 and ADL5387. More info in the following Circuits from the Lab: