Predicting the future is never easy. Similarly, knowing which types of circuit materials will be needed for the next decade’s RF/microwave applications can be difficult to predict, but the past can provide invaluable guidance. With this being the 100^th installment in this series, the previous six years of ROG Blogs provide a bit of a map for the high-frequency road ahead and what might be needed in terms of electrical and mechanical characteristics for what are expected to be large-volume applications in this industry, including in radar-based automotive electronics systems, Fifth Generation (5G) wireless communications systems, and Internet of Things (IoT) sensors almost everywhere.

This first six years of the ROG Blog offered guidance on the use of many different types of circuit materials from Rogers Corp. (www.rogerscorp.com), for everything from high-frequency analog circuits to high-speed digital circuits. It explored the effects of circuit material characteristics on the performance of different types of high-frequency transmission lines, including microstrip, stripline, and various types of coplanar waveguide (CPW) transmission lines. And it has examined how the choice of printed-circuit-board (PCB) material impacts the performance of many different types of components, such as low-noise amplifiers, power amplifiers, delay lines, filters, and resonators.

In the next few years, this industry is expected to face new challenges in circuit design, with the high-volume growth of automotive electronics systems, 5G wireless, IoT, even with the steady growth of existing wireless applications such as WiFi and WLAN.

For many high-frequency circuit designers, wireless communications systems such as Third Generation (3G), Fourth Generation (4G), and Long Term Evolution (LTE) have represented rapid growth areas. But even without a standard in place, excitement is growing for the coming of 5G wireless communications systems and the type of services they will provide in the years to come, including fast wireless data with almost zero latency. Transferring high-speed digital signals will be an important part of any future communications network and the ROG Blog from January 22, 2015, “Selecting PCB Materials For High-Speed Digital Circuits,” detailed how RO4003™ circuit materials provided the proper mix of characteristics for speeds to 25 GB/s and beyond.

Higher-frequency (millimeter-wave) signals are expected to play important roles in 5G next-generation communications systems, and the ROG Blog has already provided several installments on choosing materials for millimeter-wave circuits, such as “Making The Most of Millimeter-Wave Circuits” and “Matching Materials To Millimeter-Wave Circuits.” Since millimeter-wave frequency bands are planned for high-data-rate backhaul links throughout 5G networks, the need for circuit materials capable of reliable, low-loss performance at 50 through 70 GHz should continue to grow, prompting more ROG Blogs on this topic.

The expected boost in the number of wireless signals in use during the next decade should also focus circuit designers’ attention on the material characteristics needed for low-PIM performance. An earlier ROG Blog, “Perusing PCBs For Low PIM Levels,” explained the role of circuit materials in the design of PCB antennas and how circuit material characteristics should be chosen to minimize PIM. That blog presented Rogers’ RO4725JXR™ and RO4730JXR™ circuit laminates as non-PTFE, halogen-free circuit materials with the characteristics needed to minimize PIM. With the growing number of wireless signals to be generated during the coming decade, in high-volume applications such as 5G and IoT, the importance of minimizing PIM only increases and certainly should be a recurring topic of this ROG Blog series.

The first six years of the ROG Blog series provided circuit specifiers with key insights on different aspects of circuit materials, such as material parameters important for impedance matching, for dissipating heat, and for minimizing losses. ROG Blogs have explored such things as the importance of circuit laminate finish, in “Finish Makes a Difference in Broadband PCB Loss,” and the reason for using a high-dielectric-constant (Dk) circuit material, in “Harness High-Dk Circuit Materials.” The next 100 ROG Blogs hope to provide guidance on the best use of these high-frequency materials, as starting points for what appears to be many high-frequency, high-speed circuits in the decade to come. 

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