For the 5G millimeter wave systems, there is a desire to mount the RFICs on the backside of the antenna substrate, introducing a form requirement that drives aggressive integration. For example, the half wavelength element spacing for an antenna centered at 28 GHz is approximately 5 mm. For higher frequencies this becomes smaller, making the die or package size a significant consideration. Ideally, the entire block diagram for a single beam should be integrated in a single IC, but at the minimum, the up and down converter should be integrated with the RF front end on a single RFIC. The level of integration and technology of choice is somewhat dictated by the application, as we will see in this article.