A New Generation of RF Switches at the Heart of 5G Systems

Our present moment is characterized by the collection and analysis of data on a massive scale. Smartphones now readily stream high-definition videos, and smart devices appear in all sorts of settings—industrial, automotive, and medical, to name a few. Today, this is enabled by 5G, which provides significantly better capacity than any other mobile communications standard used to date.

Figure 1. 5G networks enable communications on a massive scale. Image used courtesy of Adobe Stock

5G networks use a range of frequency bands: a low band (sub-1 GHz), a mid band (1–10 GHz), and a high band (above 10 GHz). In the high band, frequencies enter the lower end of the millimeter wave zone. 5G's wide bandwidth and high-frequency spectrum call for systems, antennas, and components to be small, fast, and better performing than their predecessors, while also using less power and generating less heat.

However, 5G is not perfect, and the technologies it integrates are still works in progress. Network performance can be affected by greater component density causing systems to overheat, leading to higher power usage and therefore more heat generation. 5G networks also experience congestion at times, resulting in slower speeds and inconsistent performance. These issues will remain when 5G is superseded by 6G.

Technological advancements will help shrink the required hardware further while also allowing better thermal management of densely packed systems. They will also provide greater power efficiency and avoid infrastructure bottlenecks. As we'll discuss in this article, a new type of RF switch has already begun to provide performance improvements.

Switches in 5G Systems

At the heart of both 5G and 6G are switches that route signals and enable switchovers between various frequency bands. Switches for 5G setups are expected to have insertion loss below 1 dB across the spectrum. To minimize signal distortion and enable increased data rates, linearity better than 90 dBm is also crucial.

Isolation better than 30 dB is important at the higher frequencies to minimize signal crosstalk and leakage. Last but not least, switching times for networked devices should be shorter than 1 ms and be reliable for over a billion operations.

Switches are used to connect, route, and reconfigure communication networks. This function has traditionally been handled by electromechanical relays (EMRs) or solid-state relays (SSRs). Both are widely used in 5G networks, though in different roles and for different specifications. EMRs are typically used where high-power control, low loss, and high linearity are critical parameters, while SSRs are used where switching speed is prioritized for the routing of low-power signals.

The downside of these switches is that they're power-hungry, lossy, and bulky. Our emerging networks will need fast switching speeds at sub-millisecond levels. To minimize heat loss, they should have sub-1 dB insertion loss to minimize waste heat. For higher data rates, they should have > 90 dBm IP3. All of these requirements must be met across a wide frequency spectrum.

Neither EMR nor SSR combines these requirements into a single switch. Though traditional EMR and SSR technologies are sufficient for our legacy networks, our thirst for more data and faster transmission requires the benefits of both technologies without their faults.

The industry is quickly realizing that these technologies must be replaced by a more specialized approach. As a result, there is a rising interest in newer, more advanced RF switches. These switches will be the key building block in next-generation signal management for 5G and 6G networks.

Modern RF Switches

RF switches for 5G are essential in controlling the routing of high-frequency signals between components. They are also used in antennas. These switches manage complex signal paths and support a wide range of frequencies simultaneously in mobile devices, base stations, and multi-antenna setups.

By efficiently controlling the signal flow, RF switches ensure fast and reliable connections. In 5G beamforming and dynamic spectrum allocation, rapid switching is essential for seamless handovers, adaptive beam steering, and load balancing. This is especially true when devices move rapidly between cells or frequency bands.

The increasing complexity of 5G setups and antennas also means that smaller, more efficient switches are required. Here, too, RF switches are a good fit. Advanced RF switches provide higher speeds, better bandwidths, and improved energy efficiencies in 5G devices, as well as extending their battery life.

Many modern RF switches are based on silicon-on-insulator (SOI) or microelectromechanical systems (MEMS). Both technologies aim to combine the benefits of EMRs and SSRs. They offer higher-frequency operation, lower insertion losses, higher linearities, and the necessary speed for reconfigurability.

When assessing the combined performance metrics, the edge goes to the new class of RF MEMS devices. The newest generation of RF MEMS switches delivers the following across the entire frequency spectrum:

• 25 W of RF power.
• 1 dB of insertion loss out to 26 GHz.
• Isolation better than 40 dB at 6 GHz.
• DC leakage of picoamperes.
• Switching speeds of a few microseconds.
• Power consumption of microwatts.
• A purely ohmic pathway that delivers better than 95 dBm of IP3 for superior linearity.
• Availability in a miniature chip-scale form factor.

The Ideal Switch

Menlo Micro, a U.S.-based company, has developed a proprietary RF switch technology called the Ideal Switch to address the needs of modern communications. In doing so, Menlo has extracted the best features of electromechanical and solid-state switches and combined them into a patented innovation that provides unparalleled power handling and performance in very small packages.

Figure 2. The Ideal Switch. Image used courtesy of Menlo Micro

Manufactured using proprietary techniques and materials, the Ideal Switch products leverage a unique combination of semiconductor technology and cutting-edge design. The result is higher efficiency, reduced size, and a longer lifespan. Other than communications setups, they benefit a wide range of products in the following fields:

• Smart energy.
• Home automation.
• Industrial IoT.
• Test and measurement.
• Aerospace and defense.
• Consumer electronics.
• Medical applications.

Wrapping Up

When it comes to 5G and the new era of communication and connectivity, RF switches provide flexibility, speed, and high performance. Sitting at the heart of 5G systems, and also soon in 6G systems, RF switches ensure seamless handover between bands and quickly and efficiently handle signals in dynamic antenna arrays of massive MIMO setups. RF switching technology will play a pivotal role in the successful operation of all these systems for years to come.

Featured image used courtesy of Menlo Micro; background graphic used courtesy of Canva