I used OIP2 to indicate the “Output 2nd order intercept point” of both the DAC and the modulator, and I referred to “intermodulation products” during the webcast. The point really is that in a complex IF system, the OIP2 is slightly less important because you can make a frequency plan that causes the IM products from 2nd order intermodulation to fall out of band of a filter, while in a zero-IF system, those 2nd order IM products will fall on your desired signal and cause degradations in adjacent channel performance, unless the OIP2 of the modulator and DACs is good enough, making the IM products small enough amplitude to not matter. When using an RF DAC, these considerations are no longer a concern because there is no longer an analog modulator—there is only an RF DAC, so your performance is as good as your RF DAC’s linearity.
