So important that you may not know the RF front end.

IT 168 Evaluation In the past ten years, the communication industry has experienced a gradual iteration from 2G to 3G, and then from 3G to 4G. With the development of more frequency bands and the introduction of new technologies, high-speed networks have become popular, and mobile phones have also changed from short messages to more diversified intelligent terminals to meet our needs of instant downloading, social live broadcast and online games. With this change, communication performance has become an important indicator to measure a mobile phone. Among them, RF front-end (RFFE), as the core component, plays a more important role.

Speaking of RF front end, I believe many friends don't know much about RF front end. It is a series of components between RF transceiver and antenna, mainly including power amplifier (PA), antenna switch, filter, duplexer (diplexer and diplexer) and low noise amplifier (LNA), which directly affects the signal transmission and reception of mobile phone. Without the RF front end, your mobile phone can't connect to the mobile network at all.

Recently, IHS, an internationally renowned research institution, released a research report on the RF front-end of mobile phones by disassembling a variety of smart phones, and made some interpretations on the design trend of the RF front-end of mobile phones in recent years.

▲ The cost of RF front-end is gradually increasing with LTE network.

IHS said that due to the pursuit of full netcom and LTE network speed in recent years, a terminal often needs to support multiple frequency bands. The increase of this frequency band directly leads to the increase of RF front-end design complexity, and usually hundreds of components must be accommodated between square inches. Especially with the emergence of Gigabit network, the integration of multi-carrier, high-order modulation, 4x4 MIMO and other technologies makes the complexity of front-end design increase linearly. By disassembling Samsung S8, IHS pointed out that it adopted the most complicated front-end design at present. Of course, the increase of complexity directly means the increase of cost, and it accounts for an increasing proportion in the cost of mobile phone BOM, which shows its importance.

▲ Disassemble Samsung S8.

In addition, IHS also pointed out that with the development of mobile phone design, the available space of the fuselage is actually reduced, especially the space of the motherboard. Therefore, although the complexity and importance of RF front-end are increasing day by day, it is embarrassing that the space left for it on the motherboard is getting less and less.

▲ The RF front-end is becoming more and more complex, but the space left by the motherboard is getting less and less.

It can be said that on the one hand, it is the direct demand of high-speed network, on the other hand, it is the industry trend of aesthetic design. How to balance this contradiction is always a difficult problem. As an enterprise that has been deeply involved in the communication field for more than 30 years, Qualcomm has provided RF front-end solutions for the system in the industry. It has a complete core technology combination of RF front-end and advanced module integration functions, and combined with its own advantages in modem, it has derived advanced RF front-end technology, enabling mobile phones to achieve the effects of "high-speed network" and "aesthetic design".

Trusignal antenna enhancement

TruSignal antenna enhancement is divided into three technical parts, namely main diversity antenna switching technology, dynamic antenna tuning and high-order diversity receiving technology. Among them, dynamic antenna tuning technology depends on the cooperation of Xiaolong modem and RF front-end. In the process of data transmission, the modem will constantly detect the transmission channel and adjust the adaptation between the antenna and the RF front-end power amplifier in time, so as to reduce the signal loss in the transmission process and avoid dropped calls and decreased communication rate.

The switching technology of primary and secondary antennas will switch the uplink and downlink transmission of primary and secondary antennas at the critical point of signal loss, so as to ensure the smooth data transmission of mobile phones and avoid the problem of "dead grip" under the thin and light design of mobile phones. High-order receiving technology relies on additional antenna design to ensure that mobile phones can sense subtle signals from all directions and directly improve signal quality, which is inseparable from the role of RF front-end. It is worth mentioning that due to the improvement of antenna efficiency by Trusignal technology, unnecessary power consumption is correspondingly reduced, and battery life is increased in disguise.

Envelope tracking

Envelope tracking means that the voltage provided by the power amplifier (PA) is adjusted according to the envelope of the RF signal, and the maximum power saving effect can be achieved by working with the modem. According to Qualcomm's data, the energy efficiency of envelope tracking can be improved by 30% compared with the average power tracking with fixed voltage. The resulting power saving and low heating directly affect the user experience, especially low heating. The power amplifier has obvious signs of heating after working for a long time, and the envelope tracking technology solves this problem well.

Of course, these advanced technologies are not on paper. The design of modem+ RF front-end in Snapdragon has brought these technologies to many smart phones, including Samsung S8, OPPO R 1 1, which not only makes these phones have excellent connection performance, but also leaves more possibilities in design. It can be predicted that with the coming of the future 5G era and the introduction of multi-bands, the role of RF front-end will be more significant, and the scheme of Qualcomm system will bring comprehensive innovation to terminal design and consumer experience.