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Talking about the RF design of the first generation 5G mobile phone

The market responsiveness of 5G smartphones is unprecedented in the early stage of the transformation of this new wireless technology. Unlike previous evolution of 4G LTE, more mobile phone manufacturers will provide new devices to customers at the first time; it is not only the early stage of the design cycle of key modem suites and RFEE components. It can be provided to manufacturers, but also because these solutions are complete "modem-to-antenna" design, thus further speeding up the initial 5G smartphones on the market.

This paper will further explore how radio frequency technology and components support 5G devices, so that they can be launched as early as possible in the 5G network life cycle. As part of IHS Markit Technology's "prospective research" on 5G network and device performance, we evaluated at least six first-generation 5G smartphones and conducted a thorough disassembly analysis to determine the 5G wireless core components and system design. These 5G smartphones are from Samsung, LG, Millet, Oppo, Yigai and Huawei.

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Through in-depth study of the initial 5G design of these smartphones, we began to understand the main components and the vendor selection of 5G modem and RF front-end. Of the six mobile phone brands evaluated, the vast majority (5/6) of 5G design is provided by Qualcomm. One version of Samsung Galaxy S10 5G uses Exynos (Samsung LSI) solution, while Huawei Mate 20X 5G uses self-developed modem solution (Huawei Hesperian 5000). These two "exclusive" modem suppliers are usually exceptions to industry rules or specifications. The development of modems and RF front-end requires a lot of resources. But it's clear that Samsung and Huawei can afford to invest in vertically integrated 5G designs with their amazing size and scope of operations.

In the commercial aspect of 5G ecosystem, Qualcomm took the lead in releasing the Miaolong X50 modem in 2016. So far, no other commercial modem manufacturer's 5G chip has entered the smartphone. MediaTek and Ziguang Zhanrui have both released their first generation 5G chipsets, but they have not yet been used in smartphone design by any well-known manufacturers. In addition, it is noteworthy that Intel recently sold its smartphone modem division to Apple (the only customer of Intel's 4G LTE modem chip), reducing the number of suppliers in the commercial modem sector to three.

With the maturity and consolidation of the smartphone industry, only the top three manufacturers, such as Apple, Samsung and Huawei, have sufficient funds to develop their own chipsets. Other manufacturers in the market, including millet, Oppo and Vivo, all adopt proven RF designs from commercial modem suppliers. With Qualcomm's early leadership in the 5G sector, these smartphone manufacturers can better compete with the three giants using Qualcomm's mature 5G commercial solutions. This purchasing strategy enables mobile phone manufacturers to focus more on product innovation and market differentiation rather than investing limited resources in research and development of core 5G modems and RF front-end technologies.

Increasingly close integration of discrete components and RF front-end paves the way for 5G

Like 4G nearly a decade ago, LTE connections were built on existing 3G technologies; early 5G functions were implemented by adding independent chipsets to existing LTE designs. This means that 5G components are basically bolted to smartphone design, rather than being integrated into the core chipset. This is not only to speed up the launch of smartphones, but also to reduce development risks by reusing existing mature designs.

The following functional block diagram depicts the core circuit design and commonalities of six 5G smartphones evaluated by IHS Markit from modem to antenna.

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According to the above two functional block diagrams, the first generation 5G design is essentially additive. There are discrete 5G components in the design, such as single-mode 5G modem, 5G RF transceiver and single-band 5G RF front-end, but they are independent of the existing LTE RF link. This initial 5G modem design also requires additional support components, such as SDRAM and power management, but these components usually exist in the LTE part of smartphones. On the basis of existing mature 4G design, mobile phone manufacturers have extended 4G functionality with the new 5G standard. Usually, the time requirement for mobile phone manufacturers and operators to go on the market (to start first) will be reflected in the design of equipment. In this case, the early 5G smartphones included additional support components, otherwise these components would not exist in mature smartphone design. Of the six first-generation 5G smartphones we analyzed, five of the six devices have architecture similar to the first-generation 5G design. Samsung Galaxy S10 5G uses the Samsung Exynos 51005G chipset in the international version, but we find that other versions still use Qualcomm's MX505G modem. Similarly, the 5G RF front-end is basically provided by Qualcomm, which indicates that the modem and the RF front-end are tightly coupled in the 5G communication design.

In addition, the first generation 5G RF front-end includes two different classifications: Sub 6GHz 5G and millimeter wave 5G. Due to the size, power and beam forming/tracking requirements of millimeter wave 5G, highly integrated millimeter wave antenna (multiple) modules must be used. These modular antennas integrate all radio frequency components from transceivers to physical antennas. Currently, the only available millimeter-wave solution in the market comes from Qualcomm. Therefore, the millimeter-wave 5G design is provided as a complete set of modem-to-antenna solutions, while all other competitors are still in the early stage of millimeter-wave technology development (except Intel, which has withdrawn from the market to supply the smartphone industry). ) Of the six smartphone manufacturers evaluated, Samsung and LG have millimeter-wave versions of their 5G smartphones to support the deployment of 5G millimeter-wave U.S. carriers using Qualcomm solutions, such as AT&T, T-Mobile and Verizon.

Design of Second Generation 5G Modem

One of the greatest features of the first generation 5G modems is the lack of multimode support, so a separate LTE modem is required (as described above). With the maturity of the industry, the second generation 5G modem will be determined to support multi-mode and integrate LTE and 5G on the same chip. This is the only way for the evolution of smartphone circuit design. While reducing the circuit area of 5G smartphone, it also needs to reduce its power consumption and manufacturing cost. Of the six 5G smartphones in this evaluation, only Huawei uses its first 5G chipset (Ballon 5000) multimode modem design. Although this design no longer requires a separate 4G/3G/2G modem, our disassembly shows that other designs of Huawei Mate 20X are far from ideal, highlighting the challenges of early 5G technology.

Other vendors have announced the launch of second-generation modems, including Qualcomm's Miaolong X55 and Intel's XMM8160. But the reality is that in view of Intel's recent withdrawal from the market, we will only see the adoption of Qualcomm solutions. In fact, when the X55 was released, several design schemes based on it were already in the development process and were expected to be launched by the end of 2019.

The functional block diagram (Figure 4) illustrates the architecture of Huawei Mate 20X 5G smartphone. Although Huawei is the only one to use multimode 5G modem in this critical test, it also brings many design compromises. First, the Mate 20X design still uses Heise Kirin 980 SoC, which already has a built-in LTE modem. In addition, only the multi-mode Ballon 5000 modem is used for 5G/4G/3G/2G communication in actual operation, which makes the integrated modem in Kirin SoC unnecessary. A better solution is to replace Kirin 980 with a separate application processor (no modem) to reduce costs, power consumption and PCB footprint.

In addition, Huawei Mate 20X 5G is equipped with a higher capacity SDRAM for Baron 5000. A typical approach for independent modems is to package SDRAM with a capacity of hundreds of megabytes (MB) into a chip, while Huawei Mate 20X uses a surprising 3GB high-capacity LPDDR4 SDRAM (capacity scaling up) packaged in PoP, comparable to the mainstream SoC SDRAM configuration of most smartphones. From the silicon wafer level, the size of bare 7-nm Baron chip is 50% larger than that of 10-nm Qualcomm X50 (the results collected in this batch of 5G smartphones). Of course, this is not an equal comparison, because one is multi-mode and the other is single-mode, and different manufacturing processes are used, but this shows the design compromise adopted by different manufacturers to achieve 5G. The Baron 5000 will be a better comparison with the upcoming Qualcomm X55 5G modem. X55 and Baron are both multimode 5G modems, and X55 is made by 7Nm process. From this, we can infer that the size of bare chip is much smaller than that of Baron 5000.

The efficiency embodied in Huawei Mate 20X design is the simplification of RF front-end (from transceiver to antenna). Contrary to the dual wireless links designed in the first generation, 5G/4G/3G/2G requires only one wireless link, because all wireless communication standards use a single multimode modem and RF transceiver path (not two).

At present, Huawei's 5G design is limited to the radio frequency band of Sub 6 GHz (currently the most commonly used spectrum of 5G deployed internationally). For millimeter-wave support with high performance, Huawei has not yet introduced a viable RF front-end solution. This means that for operators and OEM manufacturers who now support millimeter-wave 5G network deployment, the only available option is Qualcomm's highly integrated millimeter-wave modem to antenna design.

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Huawei Mate 20X design highlights some of the challenges facing equipment manufacturers in designing 5G modems, balancing functional requirements, circuit design and cost. If Hess provides Ballon 5000 modem to other OEMs and competes directly with commercial modem providers, this evaluation of 5G initial design will show that Huawei design is not competitive in terms of cost, circuit board area and efficiency. However, given the "exclusive" nature of Huawei's design, these concerns are secondary to the ability to bring 5G smartphones to market on time. In addition, because Hess Semiconductor is an "exclusive" supplier, OEM customers have less requirements for improving design efficiency, resulting in the first generation of design is not optimal.

Optimizing Future 5G Design

The early analysis of the early 5G smartphones will eventually guide us in the direction of 5G design evolution in future products. Just as multi-mode modem will be introduced in the second generation design, it will bring single modem design and higher integration of RF front-end. With the maturity of 5G technology, the industry will look forward to further optimization of core circuit design.

What kind of 5G design will we see in the future? In accordance with the evolution of 4G LTE modems nearly 10 years ago, we will see the integration of multimode 5G modems with SoC itself in the next iteration of 5G smartphone design in 2020 (Fig. 5). This higher degree of integration will affect existing SDRAM and power management supporting SoC, eliminate additional chips on the motherboard, and more importantly, affect bill of materials (BOM) costs.

In addition, we will see a highly integrated and compact RF front-end architecture that supports both Sub 6GHz and millimeter band 5G in a single device. Just as the high-end LTE smartphones on the market today have radio frequency bands to support global roaming, the future 5G smartphones will rely on compact modem to antenna design to integrate more 5G frequency and mode support. In 5G applications, the need for modem or modem-to-antenna design optimization is critical, and any signal degradation will lead to significant delay or delay at the client. To sum up, a better, cheaper and faster 5G smartphone is coming out.

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The maturation process of components is a cycle of evolution of each new wireless standard. Early LTE designs were as complex as the first generation 5G designs we discussed in this article. With the progress of semiconductor manufacturing technology and higher integration of silicon wafers, especially the close coupling between modem and RF front-end, the industry will begin to realize the advantages of mature 5G chipset design. In addition, we anticipate that the overall cost of 5G devices will inevitably be reduced as the smartphone design will be upgraded from LTE to 5G. These advantages will be reflected in the economy and performance of the next generation of 5G smartphones coming next year to end consumers.