Efficient Design Flow for 5G NR Front-End Components

Parent Category: 2020 HFE

By Su-Wei Chang

5G New Radio (NR) millimeter-wave (mmWave) frequencies provide tens to hundreds more capacity compared to 4G, and, unlike previous standards, use dynamic beam steering to maximize connectivity by aiming as much of the signal directly to the mobile device as possible. As a result, beamforming antennas represent a new area of development opportunity for many commercial manufacturers. TMYTEK, a developer of active and passive insert mmWave products and services that are integrated with software control, has designed a groundbreaking BBoxTM beamformer box product line (Figure 1) for 5G product developers.

Figure 1 • TMYTEK BBox beamformer box.

The BBox consists of an integrated phase shifter, power amplifier (PA), low-noise amplifier (LNA), and transmit/receive (T/R) switch. The 28GHz phased array is broken into different parts to offer the greatest flexibility for developers. This highly modulized 28/39-GHz beamforming system enables 5G designers to successfully develop innovative antenna designs and baseband technology. The BBox system is a scalable and flexible system that includes a standard antenna kit, phase and amplitude controller, channel selector, up/down conversion and control host (Figure 2). It provides reliable steerable beams to test and support development of phased-array antennas and associated electronics, which must undergo rigorous calibrations and measurements under a large number of configurations through advanced over-the-air (OTA) testing to ensure optimal connectivity.

Figure 2 • BBox system.

TMYTEK component designs for base station and user equipment include a 47/53GHz filter, one of the key components for the company’s mmWave instrumentation equipment, as well as a 28-GHz phased-array antenna for 5G mmWave beamforming using antenna-in-package (AiP) modules.

The specifications for the 47-53GHz filter passband and rejection band were difficult, and in addition, the minimum feature was only about 20µm, so accurate simulation was key since the fabrication cost was high. For the 28GHz phased-array antenna, the system performance of the beamforming and beam shaping required system-level simulation, including antenna design, power combiner design, beamforming system design, and electromagnetic (EM) extraction of the layout.

Filter Design

Specialized technologies within the Cadence® AWR Design Environment® platform were implemented for the filter and phased-array antenna design. TheAWR® Microwave Office® circuit design software filter synthesis wizard enabled TMYTEK designers to synthesize the filter with the desired specifications. The circuit model and layout were generated using the wizard, and then EM simulation of the layout file was done using the AWR AnalystTM 3D finite-element method (FEM) EM simulator. Together, these tools enabled the engineers to complete the design within a short timeframe while delivering excellent agreement between the simulated and measured results.

Phased-Array Design

The phased-array generator wizard in AWR Visual System Simulator™ (VSS) system design software was used to quickly evaluate the results for the 28GHz phased-array antenna (Figure 3) by implementing a single antenna radiation pattern using either EM simulation results or measured results. The wizard was then used for the beam steering and beam shaping. The different beam-shaping tapering methods provided in the software helped the designers build the AiP module with only basic knowledge of the beamforming system. After the module was built, the layout was imported into Microwave Office software and the Analyst solver was used to simulate and verify the design. The measured results matched well with expectations.

Figure 3 • Simulated antenna radiation patterns for the BBox beamformer system.

Conclusion

TMYTEK designers were challenged with difficult specifications for the filter and antenna components in the BBox beamformer box. The design process for these components was streamlined with the use of the filter synthesis and phased-array generator wizards in the Cadence AWR Design Environment platform, saving a significant amount of time for the initial design. In addition, the integrated system and circuit simulators combined the EM results into a circuit model, the verified performance of which was validated within an RF link analysis at the system level. This unique flow saved 20-30% in design time.

About the Author

Su-Wei Chang is founder and president of TMYTEK. He holds a BSEE from Feng Chia University and an MSEE from the University of Massachusetts in Amherst.