Market Insight

In 5G smartphone designs, RF Front-End graduates from traditional supporting role to co-star with modem

August 28, 2019

Wayne Lam Wayne Lam Principal Analyst, Mobile Devices & Networks

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  • Majority of early 5G smartphone designs were found to be using Qualcomm modem and RFFE components
  • Qualcomm presently offers the industry’s only commercial millimeter wave 5G modem-to-antenna design for smartphones
  • 5G RFFE component costs make up a significant portion of overall RFFE with mmWave driving the most pronounced increase
  • Adopting a proven commercial modem and RFFE solution allows OEMs to more efficiently focus their development efforts on the overall phone designs
  • With their early-mover advantage, Qualcomm is poised to capture a larger portion of semiconductor spend within 5G smartphones.

In our continuing series looking at early 5G smartphone hardware designs, we now turn our attention to the 5G RF Front End (RFFE) section of the core electronics.  Of the six OEMs with 5G smartphones IHS Markit has sampled thus far, five of them feature a common design theme at the RFFE section; a complete 5G RFFE solution provided by Qualcomm. This vote of confidence in Qualcomm speaks not only to their critical role as a major supplier of modems but also to their growing expertise in bringing an industry-first modem-to-antenna solution to market, beating out incumbent RFFE component providers[1] and disrupting the RFFE market in 5G.

Unlike the previous transition to 4G where smartphones lagged network deployments, 5G smartphones has been available on day-one of 5G network launches. Also, smartphones are featured as the marquee device to showcase 5G capabilities.  IHS Markit has sampled seven unique 5G smartphone designs from six OEMs thus far.  The number and diversity of OEM brands in this population of early 5G devices are unprecedented especially given the RF challenges of designing for a new 5G network.  Historically, only the more technically capable OEM were the first to launch a new wireless generation of phones but here, we also have non-tradition or smaller OEMs such as Xiaomi, Oppo and OnePlus; brands unknown to the industry a decade ago during the 4G transition.

Accommodating New Spectrum in 5G

Early 5G networks are of the “Non-Stand Alone” type[2] which dictates that an anchor LTE signal is required for 5G wireless connectivity.  What this requirement means to the RFFE design is that there will be two distinct RF paths for both LTE and 5G.  This requirement will stress the current smartphone RFFE designs which are already complex due to LTE-A[3] features such as carrier aggregation and multi-band support. In this white paper, we will explore the results of the teardowns into these five Qualcomm-design 5G smartphones, compare the similarities, relative Bill of Materials (BOM) cost and point to unique design elements.

The implementation of 5G spectrum within the new networks are significant in the evolving RFFE design.  By opening larger swaths of spectrum, 5G will offer higher capacity and speeds.  However, to support those wider bandwidths, the RFFE must be re-designed accordingly to support the frequencies used.   5G frequencies below 6GHz are less challenging due to its similarly to existing LTE RFFE signals.  This 5G frequency range (FR1) is colloquially referred to as “Sub-6GHz”. The FR1 signal propagation characteristics behaves in the same way as existing high-band LTE but at a much wider carrier bandwidth (100-200MHz compared to 5-20MHz in LTE). 

The other, but more challenging, spectral range (FR2) is commonly known as millimeter wave (mmWave) 5G.  FR2 spectrum had not been previously in use in mobile phone applications due to its limited signal propagation and high attenuation.  However, the largest swaths of open spectrum reside in the frequency ranges starting at 24GHz to about 90GHz.  To overcome the traditional limitations of mmWave, special techniques in radio technology is applied to extend the usable coverage of FR2.  RF techniques such as focused beam-forming and beam tracking are deployed at the edge of the 5G network to open hundreds of megahertz of bandwidth to make them available to mobile users.  Granted, the real-world coverage of mmWave 5G maxes out at around 1000 feet from a mmWave small-cell but the sheer capacity (upwards of 800MHz) and speed made available in these virgin spectrums can truly supercharge the 5G experience.

Teardown Results

LG was one of the many OEMs who announced 5G smartphones this past February in MWC Barcelona.  The V50 ThinQ 5G is a sub-6GHz 5G smartphone initially designed for US carrier Sprint[1] and later repurposed for other global carriers deploying sub-6GHz (typically at band N77/78 @ 3.5GHz). 

LG employs the first-generation Qualcomm X50 5G design which includes a discrete 5G transceiver (SDR8154) and a pair of RFFE modules, the QPM5650 transmit module and the QDM5650 diversity receive module to support the single band N77/78 sub-6GHz 5G network.  As we will see in subsequent teardown results, this first-generation design has been adopted by three other OEMs in the same RF configuration[2].

 

One design challenge of first-generation 5G smartphones other than the RFFE is finding enough PCB surface to mount the extra 5G components.  Here, the Qualcomm X50 modem is seated on the top side of the PCB adjacent to the Snapdragon 855 SoC while the remaining RFFE components are mounted at the bottom side of the PCB.  LG opted to mount all the 5G components onto one main PCB as opposed to making a modular (i.e. stacked PCBs) design that can be swapped out to create LTE-only or alternate 5G versions of the same phone.  Therefore, the LG V50 ThinQ is essentially a purpose-built 5G smartphone designed around the Qualcomm architecture.

The Oppo Reno 5G is a 5G version of their flagship Reno device (LTE-only).  In order to accommodate new camera features, the Reno has been developed on a larger chassis which in turn enabled the use of a larger full-screen display and subsequently a larger internal battery.  This growth in physical design creates additional headroom to place 5G components into the phone.  This strategy allows Oppo to market and sell two different versions of their flagship smartphone with essentially the same design.  Common platform designs, of course, helps with manufacturing scale and component sourcing.  This is a popular strategy amongst competitive OEMs seeking to reduce supply chain complexities.

Within the Oppo Reno 5G, a modular RF board is used to swap in [and out] RF components based on different global regions and markets.  This approach allows Oppo to not have to over-invest in RF components not necessary in specific markets.  Here again, the Qualcomm X50 modem, SDR8154 transceiver and the pair of RFFE modules (QDM5650 & QPM5650) are used to complete the 5G modem-to-antenna design.  Since this Oppo Reno 5G was acquired in Europe, the RFFE supports the single common frequency (N78) used by most early European 5G network deployments.

The Xiaomi Mi Mix 3 5G is another Qualcomm sub6-GHz RFFE design. Just like the Oppo Reno discussed earlier, the Mi Mix 3 5G is designed to be highly configurable so to serve different global markets.  Xiaomi leveraged the existing Mi Mix 3 design platform which to create a 5G version.    Xiaomi adopted this design approach because it is helpful to not only get a 5G market sooner but also in overall device SKU management.

In keeping with the OEM’s company ethos, the Xiaomi Mi Mix 3 5G is the price-leader of the bunch with a starting price of €600 or about $680 suggested retail.

Xiaomi employs a completely modular modem-to-antenna 5G design (whereas Oppo uses a modular RFFE design) which is ideal to add 5G functionality quickly into a market proven design.  The 5G PCB assembly above contains the complete set of X50 modem, SDR8154 transceiver, QPM5650 Front End and QDM5650 diversity module.  There are also un-populated chip landing pads in the Mi Mix 3 5G board.  This is likely a design consideration for markets that have 2 different Sub-6GHz 5G frequencies (which is the case for their domestic Chinese market).  The model sampled here was designed for the European market which is using the predominant band N77/78.

The OnePlus 7 Pro 5G is the fourth sub-6GHz 5G design sampled by IHS Markit.  Just as with the LG V50 5G design, all Qualcomm 5G components are mounted onto a common main PCB.  However, unlike the LG V50, the OnePlus 7Pro is not a purpose-built 5G smartphone platform.  OnePlus leveraged their OnePlus 7 Pro platform to add in 5G capability – employing the same strategy as both Oppo and Xiaomi. By reusing existing designs, OnePlus was able to leave much of the LTE-only designs alone (reducing cost).  However, in order to accommodate 5G components, OnePlus opted to spin a new PCB design instead of going the modular route used by Oppo and Xiaomi described earlier

The OnePlus features an oddly shaped main PCB.  The reason for this is to create the space necessary accommodate the articulating front facing camera.  The selfie camera pops up when needed and retracts back into the phone when it is not to reserve the uninterrupted full display design.  For OnePlus, the only compromise it took in this 5G design is to create a completely different main PCB design between the LTE-only version and the 5G version.  While this strategy increases manufacturing complexity, it is done so to keep the phone thickness as low as possible given the room required for the pop-up selfie camera.  The OnePlus 7 Pro is an exclusive 5G smartphone offered on the EE network in the UK and operates on 5G band N78.

The last of the early 5G teardowns comes from Samsung.  The Galaxy S10+ 5G is notable for being one of the few mmWave 5G devices available on the market.  Unlike the Oppo, Xiaomi or OnePlus, the Samsung is developed on an even-larger version of the Galaxy S10 series flagship phone.  Therefore, this purpose-built 5G smartphone platform is more akin to the LG V50 5G than the other Chinese OEMs.  The Samsung Galaxy S10+ 5G comes in two different versions.  One for Sub-6GHz 5G (International markets) and another for a mmWave 5G network exclusive to Verizon in the US.  The model we will be discussing is the mmWave version.

For the mmWave version, Samsung has opted to use a Qualcomm X50 modem solution instead of their own Exynos platform.  Unlike the previous four Sub-6GHz 5G phones reviewed, this Galaxy model features three mmWave antenna modules (QTM052) located strategically on the back side of the device.  Due to the high attenuation properties of mmWave, the RF Front End design had to be completely re-imagined.  The solution provided by Qualcomm here is to use a highly integrated transceiver-to-antenna module design.  Since mmWaves can be blocked by the simple act of holding the devices, multiple antenna modules are deployed so to always have an exposed mmWave antenna module during normal usage. 

The use of mmWave is probably the most difficult technical challenge 5G for the industry to overcome.  Unlike other global markets where mmWave is on the roadmap but not yet deployed, the US carriers such as AT&T, T-Mobile and Verizon decided to go first to market with mmWave 5G.  The benefits of mmWave 5G is clear, however, the RF design presents an extremely difficult engineering problem and ultimately added cost to the overall design.

Samsung’s use of Qualcomm’s mmWave solution speaks volumes about the maturity of the Qualcomm modem-to-antenna capability.  It is unusual for a very large and capable OEM such as Samsung to outsource their RFFE design, but in the case of mmWave, only Qualcomm has a proven design that works presently.  Amongst the incumbent players in the RFFE market, only Skyworks has mmWave solutions, however, not mature enough to be commercialized.

The PCB figures below illustrate the complexity of the Samsung Galaxy S10+ 5G design.  Note that in the main PCB, the 2 unpopulated landing pads are there because in a later version of the Galaxy S10+ 5G, the smartphone is designed with both mmWave and Sub-6GHz RFFE.  The larger pad is to support the SDR8154 5G transceiver and smaller one is for a 5G PAMiD for band N41 (QPM5580).

Samsung engineers created three internal cavities for the three Qualcomm QTM052 mmWave antenna modules to be mounted right under the back cover for best RF reception. 

Millimeter wave antenna modules need to be highly integrated in order to reduce the distance (and signal loss) between RF components.  The module includes a series of four phased-array antenna[1] packaged with Power Management IC (PMIC) and transceiver just below the antenna stack. Within the mmWave communication regime, the signal budget of the 5G RFFE is crucially important.  By choosing to go with the Qualcomm solution as opposed to their own RF solution is a testament to the early technical leadership of Qualcomm in mmWave 5G technology. Having the complete modem-to-antenna solution also is critical in ensuring that the 5G radio is optimized for signal reception and low power consumption.

The need for redundant mmWave antenna modules will obviously increase BOM cost of mmWave 5G phones.  Over time, antenna modules and other 5G RF components will come down in price as scale builds for mmWave 5G antenna module supply chain.  However, it is an unmistakable fact that first-generation 5G RFFE will have a significant cost premium over that of the existing LTE RFFE solutions.  So much so that, in this first-generation example, the cost of mmWave components far exceeds that of a multiband LTE RFFE.

 

First-generation 5G RFFE cost premium

The chart above summarizes the cost premium of adding 5G RFFE into the five first-generation 5G phones analyzed in this paper.  Note that the cost of 5G basebands are excluded in this selective BOM cost analysis. Only components from the RF transceiver to the antenna are used for LTE and 5G RFFE cost comparisons. 

The teardown data shows that Sub-6GHz 5G RFFE carries a cost premium of around half of the cost of existing LTE RFFE.  While the mmWave solution (illustrated by the Samsung device) represent a staggering twice the cost of existing LTE RFFE.  We must caution that these early results were expected to be high since first-generation design always carry a cost premium.  Just as with early LTE designs a decade ago, subsequent generations of 5G phone design should lessen the 5G RFFE cost premium.  In mature 5G designs, the 5G RFFE is expected to be absorbed into an integrated 5G/4G/3G RFFE design. This cost premium chart highlights the significance of 5G RFFE and can be used to argue the point that in terms of component cost, 5G RFFE is just as important as the modem chipset.

It is still early innings of 5G smartphone design and bigger changes are undoubtably on the horizon for the RFFE components industry.  We look forward to the potential technological break-throughs and advanced capabilities yet to come.

 

Importance of Modem-to-Antenna Design in 5G

As discuss in the previous white paper, the 5G era opens new challenges for the core electronics supplier.  Specifically, no longer are modem capability the standard measure of capability but the entire modem-to-antenna design is considered the new standard of 5G component offerings.  Qualcomm has clearly captured the first-mover advantage of this new design paradigm of a complete 5G RFFE offering but the incumbents RFFE suppliers are not taking this market disruption lying down.  Expect the RFFE components market to heat up as incumbent component makers respond by offer more complete RFFE solutions as 5G smartphones mature.  For smartphone manufacturing, ultimately it boils down to a balancing act of cost verse performance.

The common thread that connects all five 5G smartphones featured in the teardown analysis is the fact that they are all using the first-generation designs featuring the Qualcomm X50 platform.  More significantly, a complete Qualcomm modem-to-antenna solution is used in each example – irrespective of the fact if it was either Sub-6GHz or mmWave RFFE.  The fact that Qualcomm is gaining a higher share of smartphone components in the initial round of 5G phones tell us that:

  • Pre-baked 5G solutions help OEMs go to market faster.
  • Complete modem-to-antenna solution saves development cost and de-risk early 5G designs (just as it has done in 4G LTE)
  • Having a single component supplier from the modem-to-antenna has other benefits such as optimization for power consumption up and down the RF chain
  • Ideal design and supplier choice for OEMs as RFFE increases in complexity
  • Few competitive 5G component providers driving early wins for Qualcomm’s complete modem to antenna solution

 

What to Expect in 2nd Generation 5G RFFE Designs

Moving into the new design cycle for 2020, second-generation 5G solutions are expected to feature tighter component integration between 4G LTE and 5G NR.  Also, we will begin to see 5G devices that combine both Sub-6GH and mmWave in the same RFFE.  These designs will allow for better chip-level integration, convergence of 4G and 5G RFFE and reduced overall cost.  Second-generation 5G design are defined as multimode 5G/4G/3G/2G capable modem (single chip modem) capability and converged single RF transceiver handling both LTE and 5G as well as a converged RFFE design.  Multiple 5G designs based on Qualcomm’s X55 second-generation 5G platform are slated to be released allowing OEMs to make bigger strides in component integration and cost optimization of the modem as well as the RFFE.  Other merchant modem suppliers that have announced multimode 5G/4G/3G/2G designs include Mediatek and UniSoC, however, to date, these remain mainly modem-only pre-production solutions without a companion 5G RFFE design.  Captive providers such as HiSilicon (Huawei) and Exynos (Samsung) will likely offer newer generation 5G designs, but again, not a complete modem to antenna solution.

The RF design challenges of mmWave 5G will still be present in the second-generation 5G phones. Millimeter wave attenuation continues to present the problems for mobile RFFE designs.  The top three global OEMs [Samsung, Huawei and Apple (Intel acquisition)] have some mmWave capabilities but they all trail Qualcomm to market with a viable solution.  As for Qualcomm’s mmWave technology evolution, the component maker is preparing smaller antenna module designs which should better aid in accommodating smartphone industrial design by allowing for easier placements of mmWave antenna modules.

As the industry moves through the 5G transition in the coming years, significant changes to the RFFE landscape are expected.  Large OEMs will likely attempt to move away from a single supplier modem-to-antenna solution in order to preserve multi-source capabilities, but the benefits of a complete solution are hard to ignore, especially for competitive OEMs with ambitions of growing their market position with 5G technology.

 

Conclusion

With every new technology transition comes opportunities for market disruption.  While the RF Front End market has several incumbent players that are best in class for specific RFFE niche components (i.e. Avago/Broadcom for BAW filters, PAMiDs for Qorvo and Filters/Antennas for Murata), no incumbent supplier has assembled a complete solution from modem-to-transceiver-to-RFFE and antenna until now.  Qualcomm’s entrance into the RFFE market is clearly targeted at this new opportunity.  The success of this strategy hinges on many factors, least of which are 5G adoption, cost of RFFE solutions and competitive forces from incumbent players.  However, for the first round of 5G, Qualcomm appears to be holding a winning hand with their modem-to-antenna offering.


[1] Represents a 2x2 MIMO configuration, future Stand-Alone mmWave networks will employ 4x4 MIMO designs


[1] 5G band N41 at 2.5GHz with over 100MHz in bandwidth

[2] Sprint version of LG V50 ThinQ 5G supports 5G band N41

 


[1] Primarily Broadcom/Avago, Skyworks, Qorvo and Murata

[2] 3GPP Release 15

[3] LTE Advanced / LTE Advanced Pro

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