As 5G innovation forges on, radio systems continue to emerge. Each system has a range of requirements, including specific RF filter performance needs, and it’s up to the 5G FR2 Ecosystem of suppliers to meet that demand. In response, Knowles Precision Devices (KPD) supports a wide variety of 5G radio applications.

Around the world, 2019 was a busy year for 5G, with standards being finalized, large networks beginning 5G operations, and mobile device manufacturers releasing 5G-capable phones. Just one year after the official launch of 5G on November 1, 2018, the Global mobile Suppliers Association (GSA) identified the launch of 50 commercial 5G networks along with 328 operators in 109 countries that announced investment in 5G. Let’s look at some of the big moments for 5G from 2019.  

In the race to implement mainstream 5G wireless communication, the world is waiting to see if this next-generation network will achieve a hundredfold increase in user data rates. This transformative technology not only boosts performance for the latest cell phones, but also for fixed wireless access (FWA) networks and Internet of Things (IoT) smart devices. In order to reach 10 Gbps peak data rates, the increase in channel capacity must come from somewhere. A key innovation at the heart of 5G is utilizing new frequencies greater than 20 GHz in the millimeter wave (mmWave) spectrum, which offers the most dramatic increase in available bandwidth.

RF Filters are an integral part of radio systems, required for keeping the right signals ‘in’ and the wrong signals ‘out’ on both the Transmit and Receive sides of the system.

As mobile wireless technology moves from LTE to 5G, a common question we hear is “How is filtering going to be handled in the unfamiliar territory of millimeter wavelengths?” There is a lot of uncertainty around what filters will be required, where they need to be placed in the base station, how good they need to be, and so forth.

The millimeter wave (mmWave) part of the electromagnetic spectrum is at the high end of the microwave region, which spans ~300 MHz to 300 GHz, and is usually taken to mean frequencies from ~30 GHz to 300 GHz and wavelengths in the range of 1mm to 1cm (Table 1). This dramatically increases available bandwidth, thus expanding achievable data rates, which makes these frequencies extremely interesting to teams around the world working on fifth generation (5G) communications.

One of the questions we get asked regularly is:

‘why not just integrate a filter in the board stack?’

Our answer to this comes in two parts: First there are manufacturing tolerances to consider, and second there is size.

With the promised delivery date of 5G wireless communication fast approaching, the world is waiting to see if this next-generation network will hit its ambitious goals of 10 Gbps peak data rates, less than 1 ms latency, 10 times greater energy efficiency, and more. In past decades, each generation of mobile systems – from 1G analog systems to 2G digital standards to 3G mobile broadband capabilities to 4G LTE and LTE-Advanced networks – has overcome a unique set of challenges. Leaps in technology are necessary to enable these advancements in performance.

Planar Filters

Manufactured using a thin-film process, Microstrip (planar) filters can offer a high quality factor (Q) and a reduced packaging envelope when compared to discrete lumped element designs, and are more practical at higher frequencies. The thin-film design can hold tighter design tolerances due to the distributed transmission lines forming resonant structures. Planar filters are a robust solution, attractive for applications ranging from established platforms, such as military warfare, to emerging technologies, like 5G. Below are some general-purpose resources for additional background, applications, and benefits of Microstrip filters: 

In an earlier Blog post we discussed the Shannon-Hartley Theorem in the context of 5G mmWave applications: