The model is built up on a base of eight data streams, connected to a varying number of RF chains. The power consumption of individual circuit blocks is based on currently available technology.Example Analysis: Antenna Centered at 28 GHz with EIRP of 60 dBmįor this analysis, we consider a typical base station antenna system with an EIRP requirement of 60 dBm. The level of integration and technology of choice is somewhat dictated by the application, as we will see in the example analysis. 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. For higher frequencies this becomes smaller, making the die or package size a significant consideration. For example, the half wavelength element spacing for an antenna centered at 28 GHz is approximately 5 mm. Depending on the radio requirements, GaAs may be required for the power amplifier and low noise amplifier, but SiGe B iCMOS enables a higher level of integration if it can meet the requirements.įor 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. The up and down conversion and beamforming functions can be implemented efficiently in SiGe B iCMOS. For example, data converters are now developed in fine line CMOS processes, resulting in sampling rates in the GHz range. Legacy systems are comprised of a combination of CMOS, SiGe B iCMOS, and GaAs, with each technology selected to provide the optimum performance. Historically, millimeter wave systems have been built up using discrete components, resulting in large form factors and high cost. In these paths, we employ phase shifters and attenuators to shape the beam.
Now, drilling into the block diagram of the radio section of the millimeter wave system, we see a classic heterodyne structure connected to a multiplicity of RF paths. In this article, we will work through a simple example of a large scale antenna array, to examine the optimum technology choice for the millimeter wave radio. The digital streams may be combined in a number of fashions, whether to direct all energy at a single user with high layer MIMO, or to support several users with multiuser MIMO.įigure 1. As shown in Figure 1, a combination of m data streams are split into n RF paths, to form beams in free space, making the total number of antenna elements a product of m × n. In this architecture, a combination of digital (MIMO) and analog beamforming is employed, to overcome the high path loss and improve the spectral efficiency.
It’s generally agreed that hybrid beamforming, such as that shown in Figure 1, will be the architecture of choice for 5G systems operating at microwave and millimeter wave frequencies. RF Technology for the 5G Millimeter Wave Radio