We all know that the smartphone experience depends on the SoC mobile platform it is equipped with, which in turn is composed of UNITs such as CPU, GPU, ISP, NPU and Modem (baseband, also known as Baseband).
Who is affecting the speed, latency and stability of a smartphone when surfing the Internet? I believe that the answer of many friends is the baseband.
However, the baseband is not the only one that affects network performance, and the RF + antenna module is also the behind-the-scenes hero who allows mobile phones to surf the Internet.
Theoretically, the complete RF module contains "RF + antenna", but for ease of understanding we have broken them into two parts. If you are interested in the antenna design of mobile phones, you can refer to "5G mobile phones rely on baseband is not enough!" Antenna design also has to be surgical! In this article, this article we will lock the eye on the RF module.
Let's start with Huawei phones
Last year, Huawei launched a series of new 4G mobile phones, including Mate 40 4G, Mate X2 4G and nova 8i (equipped with Snapdragon 662), which is much cheaper than the starting price of the 5G version.
Kirin 9000 integrated Baron 5000 baseband
Seeing this, it is estimated that many friends will have a question - the biggest feature of Kirin 9000 is the integration of 5G baseband, which should theoretically be able to natively support 5G, so why does the new mobile phone equipped with it only support 4G? Did the 5G base be brought to "castration"?
Look at a strange phenomenon
Among the popular 5G SoCs available today, in addition to the Snapdragon 865/Snapdragon 870, which needs to be attached to the Snapdragon X55 baseband, almost all other chips are directly integrated with the 5G baseband.
The question arises again, all are equipped with the same SoC of the smartphone, why some models of the network speed is faster and more stable, some models of the network experience is very poor?
Is there a difference between the strength and weakness of the same baseband?
The "courier department" of mobile phone 5G network
If a mobile phone wants to activate the 5G network, it not only needs 5G baseband, but also 5G RF modules and supporting 5G antenna modules, and they can also be formed into a "courier department".
Among them, the role of the baseband is the "packing/unpacking" of the express delivery station, responsible for the analog signal through the AD digital-analog conversion circuit, complete the sampling, quantization, coding, into a digital signal (can be understood as the sound, the picture into 0 and 1); the role of the RF module is the sorting of the express package, the digital signal sent by the baseband is modulated, such as filtering, amplification, demodulation and decoding, etc.; the antenna module is responsible for sending the modulated signal out, just like the courier, It is only the base station built by the recipient for the operator.
It should be noted that the above courier process is reversible.
For example, the base station as the recipient can also choose to send mail, through the antenna this courier received, after sorting by the radio frequency module, and finally by the baseband to restore the packaged digital signal into an analog signal, the countless 0, 1 back into the sound and picture is perceived by the user.
Easily overlooked RF modules
The key word for 5G RF modules is "module", which is not a chip, but a collection of chips and components.
Under normal circumstances, when we see the disassembly picture of the mobile phone, the most concerned is usually the main chips such as the eye-catching CPU (SoC), memory, flash memory, baseband and power management on the PCB motherboard.
Do you think there are a lot of these chips? So when you see a larger number of more complex RF module-related chips, is there a sense of "dense phobia" déjà vu?
The chips in the circle in the figure all belong to the category of RF modules
RF modules are ultra-complex chip matrices, and missing any of them or components may lead to limited network functions (such as 5G).
Although Huawei has reached the industry's first-class level in the research and development and performance of baseband chips, it still relies on other suppliers in the field of RF modules. Due to well-known reasons, part of Huawei's supply chain has been "stuck neck", and in the absence of 5G-related RF chips, it is reasonable for Huawei mobile phones to restart 4G in 2021.
The basic composition of an RF module
The English name of radio frequency is Radio Frequency, which is the "RF" we often chant, which belongs to the functional module with the ability to transmit high-frequency electromagnetic waves over long distances in the field of mobile phones.
In general, a complete RF module consists of three parts: an RF transceiver, an RF front end, and an antenna. The RF front end includes a power amplifier, envelope tracker, low-noise amplifier, filter, antenna switch, antenna tuner and other components.
The working principle of RF modules is very complex, and we will not introduce them in detail due to space limitations.
In simple terms, the signal frequency sent from the baseband chip is very low, and the main task of the RF module is to modulate this signal to modulate the low frequency to such as the 900MHz band of GSM, the 1.9GHz band of 4G LTE or the 3.5GHz band of 5G. At this time, although the signal frequency has increased, there is still a problem of small power, and it is necessary to use a power amplifier to obtain sufficient RF power, and then it will be sent to the antenna, and then the interference clutter will be eliminated by the filter, and finally emitted through the antenna oscillator.
Other components of the RF module also perform their respective functions, such as the RF antenna switch to control the antenna on and off, while the antenna tuner can "fiddle" with the antenna for optimal transceiver. The reason why there is a difference in the strength of 4G/5G signals between the configuration of smart phones is the layout design of the RF module (including the antenna) and the actual performance of the related chip components, if the mobile phone manufacturer compresses the cost in this regard, the result is often that the support frequency band is small, the ability to pass through the wall is poor, and it is easy to lose packets, delay, disconnection and stuttering.
Qualcomm's "turnkey" mode
In the era of 2G mobile phones, MediaTek swept thousands of troops with the "turnkey" model (MediaTek provides complete chips and supporting systems and software integration, OEMs only need to fine-tune the appearance of mobile phones and system interfaces and then find a foundry to produce directly) to sweep thousands of troops, and thus won the reputation of "the father of cottage machines". In the era of 5G mobile phones, Qualcomm's RF system is also on the road of "turnkey".
As we mentioned earlier, 5G RF modules have long been monopolized by Broadcom, Skywork, Qorvo, AVAGO, muRata and other manufacturers, mobile phone manufacturers in the purchase of Qualcomm Snapdragon, MediaTek Tianji and other SoCs and supporting (or integrated) baseband, but also need to buy a lot of third-party RF transceivers and COUNTLESS chips from the RF front end, combined with a complex antenna matrix, in order to achieve a complete 3G/4G/5G network function.
FactorY A makes baseband, FactorY B manufactures RF, Factory C manufactures antenna, and finally mobile phone Factory D completes the final integration and docking, this decentralized process is too complex and full of uncertainty, and it is extremely difficult to make perfect collaboration between chips from different manufacturers.
Qualcomm has become the world's largest supplier of baseband chips by virtue of its technology and patent advantages in the field of baseband chips, and almost all Android mobile phone manufacturers around the world have adopted Qualcomm Snapdragon mobile platform and Snapdragon baseband chips. At the same time, Qualcomm also provides an end-to-end solution for the RF front end, including power amplifiers, filters, RF transceivers and antenna tuners, which means that from the baseband to the antenna can be built using Qualcomm's components.
Compared with the decentralized 5G module, Qualcomm's integrated 5G module is also conducive to reducing the final size of the system and reducing the occupation of mobile phone space. In addition, these "blood-related" chip matrices enable deeper optimization integration, bringing technologies and features such as broadband envelope tracking (ET), AI-assisted signal enhancement, multi-carrier optimization, decoupling tuning, and multi-SIM card enhancement concurrency.
We may wish to refer to the disassembly picture of the Samsung Galaxy Note 20 5G UW of the United States Verizon Edition, which comes from Qualcomm from the baseband to a large number of components of the antenna, including several power amplifiers (such as QPM5625), envelope trackers (1 QET6100 and 2 QET5100 modules, etc.) and grading modules. To enable millimeter wave support, the product also includes two of Qualcomm's latest QTM535 mmWave antenna modules, which integrate components such as antennas, RF front ends, and transceivers in a very compact size.
The point of localization is broken
With the continuous iteration of communication technology, the capital and technology investment required are getting bigger and bigger, the market competition is becoming increasingly fierce, the players in the RF front-end market are also in the continuous mergers and acquisitions, and the presence of domestic RF front-end manufacturers is very low. For a long time, we have lacked domestic suppliers who can provide a turnkey package like Qualcomm.
The good news is that there are more and more domestic manufacturers that can make a breakthrough in the 5G RF front-end market, such as domestic 5G SAW filter manufacturers mainly have Tianjin North and Kaiyuan Communications, etc. Domestic 5G PA power amplifier modules have also formed a multi-strong pattern represented by Huizhi Micro, Weijie Chuangxin, Ruishi Chuangxin and Onry Micro, It is reported that Huawei will return to the 5G sequence in the new flagship machine listed in 2022, which shows that it has solved the problem of chip being stuck in 5G RF.