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Dissecting a 5G 28-GHz Phased-Array Transmit Chain (.PDF Download)

Oct. 29, 2018
Dissecting a 5G 28-GHz Phased-Array Transmit Chain (.PDF Download)

5G is expected to offer extremely fast rates with extremely low latency. To achieve these tough specifications, the operating frequency must be in a region where high bandwidth and high speed is available. That means a move toward the millimeter-wave (mmWave) band.

The mmWave band had always been viewed as unsuitable for mobile communications, mainly due to high loss and propagation issues. However, research has shown that these propagation issues can be addressed and overcome with phased arrays and beamsteering antennas.

A phased-array antenna is composed of multiple radiating elements. Each element is connected to a phase shifter, which forms the beam that steers the antenna via constructive or destructive interference. Phased-array antennas allow engineers to enter the mmWave spectrum and achieve the high bandwidth and high speeds that 5G promises. Within the mmWave spectrum, the 28-GHz band has been chosen as one of the candidate bands to quantify 5G.

This article discusses the process involved in the design and simulation of a 5G 28-GHz phased-array transmit chain, as well as the theory behind each step in the process. Starting with electromagnetic (EM) circuit co-simulation, results and analysis that were uncovered during the design phase are detailed.

EM/Circuit Excitation and Co-Simulation

5G presents considerable design and simulation challenges, especially when combining high-frequency circuit design elements of multiple manufacturing technologies with different model abstractions including physical EM models. All of this must be combined and co-simulated simultaneously.

EM coupling from the physical designs and their interactions with other components in the system needs to be modeled and accurately accounted for. For this reason, 5G designers desperately need good tools that can integrate and co-simulate these models and technologies together and account for all their interactions, or else the simulation results will be off and result in product failure.