In the ADL5380 (Quadrature demodulator 400MHz - 6 GHz) datasheet, the recommendation in the 3-4 GHz frequency range is to set the ADJ resistor to 200 ohms to Vs to give Vadj ~ 4.8V. See e.g. table 3, header on page 11 and table 4.
However, figure 26 shows that setting Vadj ~ 2.4V (as for 5-6 GHz) gives higher IIP3 and lower noise figure compared with Vadj @ 4.8V. The only disadvantage seems to be degraded IIP3 at lower temperatures.
So why is it recommended to set Vadj ~ 4.8V for the 3-4 GHz frequency range? Why not 2.4V?
Many thanks for your help!