I am comparing two IQ modulators 5386 and 5385. It was described in the datasheet that ADL5386 has an attenuator that can follow the modulator. My question is: we already can suppress the modulator output signal to almost zero by lowering the amplitude of I and Q, so why do we want to add an attenuator after that. In other words, we can get almost infinite dynamic range by just controlling I and Q, why would an attenuator help on that?
Thank you very much!