Tuned for Performance

Antenna tuning and its role in 5G

Like 4G before it, 5G is complicated. We highlighted this in a recent blog article dedicated to the importance of smartphone system-level design. 5G significantly increases complexity in device design with new spectrum, a growing number of band combinations and the introduction of wider channel bandwidths. This brings with it a multitude of challenges linked to interference and power inherent in the system design between the modem and antenna — what’s commonly referred to as the RF front end.

A key technology in the RF toolset designed to address these challenges is antenna tuning. The antenna is the final connection between device and network and so has a direct impact on performance. To maximize the performance of the modem and the entire RF system, it’s critical that the antenna is tuned. Failure to do so badly compromises the capabilities of the modem. It means the transmit power evaporates, interference problems arise and range is shortened, affecting everything from data speeds, to call quality, network coverage and battery life.

The difficulty here is that modern smartphone design doesn’t make life easy. Form factors have shrunk, leaving little space for antennas, and design choices with unfriendly materials like metal have further complicated matters. At the same time, new frequency bands, such as millimetre wave, and technologies including carrier aggregation and MIMO (for both cellular and Wi-Fi networks) have enabled higher data rates, but they also need more antennas. Eight or more antennas will be the norm in the age of 5G.

This has put a huge burden on antenna design and significantly heightened the role of antenna tuning. Without technologies from Qorvo, Qualcomm, Skyworks and others, it wouldn’t be possible to deliver the benefits of carrier aggregation, MIMO and the promised throughput and capacity of 5G. Antenna tuning allows devices to operate efficiently across a huge range of spectrum from low to high bands.

The merits of this technology are easy to overlook but, we reiterate, highlights the role of a complete smartphone system design from modem to antenna. For example, Qualcomm has an adaptive antenna tuning solution known as Signal Boost. Using a combination of aperture and impedance tuners as part of a closed-loop system that takes advantage of the modem’s intelligence in real time, Signal Boost allows a strong signal to be constantly maintained by dynamically switching and fine-tuning antennas used for both transmit and receive.

This means better coverage, longer battery life and faster, more consistent data speeds. Qualcomm claims the technology delivers up to 4dB recovery in the transmit power needed and a 3dB improvement in receive power. Gaming is a good example of an application of the technology, as the system can intelligently switch to unencumbered antennas depending on how the user is holding the phone, dramatically affecting data speed and latency.

The advantages are obvious for users, but the wider ecosystem also stands to gain. Carriers benefit from improved network coverage and a superior experience provided to consumers. The technology also delivers techniques that boost bandwidth, such as carrier aggregation, by enabling antennas to communicate on multiple bands simultaneously. The greater the number of devices with efficient antenna tuning, the better the experience for all users of a network.

The benefits also extend to manufacturers. Antenna tuning reduces the need for more antennas to enable carrier aggregation, which lowers cost and allows for more flexibility in design and form factor. Similarly, with antenna tuning integrated as part of a broader system-level design, manufacturers can remove enormous complexity and reduce time-to-certification and time-to-market.

The 5G transition will magnify the complexity in modems and RF for the entire industry. As with 4G, it will add to the list of carrier requirements and steps needed from manufacturers to ensure smooth and seamless operation. Complete and highly optimized chipset and RF front-end solutions that can guarantee a high-level of performance benefit the entire chain to end users. Not only is the reverse true, but poor selection or integration of technology could taint 5G in this early phase of adoption.

A version of this article was first published by FierceWireless on 14 November 2019.