With the commercialization of LTE-Advanced (LTE-A) technology and the gradual maturity of 5G standards, the radio frequency system of mobile communication equipment is facing major upgrades and transformations. In order to support the ultra-wideband of 100MHz, the operation of more than forty frequency bands, and reduce interference noise, system manufacturers plan to increase the use of radio frequency components such as low-noise amplifiers (LNA) and power amplifiers (PA). At the same time, radio frequency front-end modules (FAM) are also required to improve functional integration, prompting chip manufacturers to accelerate the development of a new generation of radio frequency solutions.
Mai Zhengqi, associate director of radio frequency and protection components of Infineon's power management and multi-electronics division, pointed out that with the rise of multi-frequency multi-mode LTE and LTE-A designs, mobile phone manufacturers are paying more attention to various components in FAM, such as PA , LNA, switches and filters have seen a sharp rise in demand. This change has stimulated the enthusiasm of silicon germanium carbon (SiGe:C), gallium arsenide (GaAs) and complementary metal oxide semiconductor (CMOS) RF component suppliers, who have invested in the development of new RF products.
In addition to the full launch of LTE commercialization in the United States, Japan and South Korea, mainland China is expected to issue 4G licenses in the second half of this year to accelerate TD-LTE operations. Taiwan also expects to successfully issue licenses before the end of the year. This will enable LTE to enter a period of rapid growth and develop towards international roaming and multi-frequency and multi-mode specifications that are backward compatible with 2G/3G. At the same time, telecom operators in South Korea and the United States have also begun to commercialize LTE-A.

In order to integrate more radio frequency functions in a limited space, the radio frequency FAM design of multi-band multi-mode LTE mobile phones must adopt a highly integrated design solution. Currently, LTE mobile phones need to support more than a dozen frequency bands, and the number of PA, LNA and RF switches is twice that of 3G mobile phones. In the future, as mobile phones develop toward LTE-A and 5G with higher speeds, larger bandwidths, and more diverse frequency bands, the use of radio frequency components will increase significantly, driving chip manufacturers to improve their products. Integration to reduce space and power consumption.
Mai Zhengqi analyzed that traditional gallium arsenide RF solutions are difficult to integrate with other system components due to the particularity of the manufacturing process. Therefore, chip manufacturers are accelerating the advancement of next-generation process and packaging technologies. For example, Infineon is focusing on silicon germanium carbon material processes and combining it with small wafer-level packaging (WLP) solutions to create MMIC LNAs with high performance, high integration and support for high-frequency switching. Qualcomm also launched CMOS PA to integrate more peripheral components through the CMOS process.
Mai Zhengqi also revealed that silicon germanium carbon is comparable to gallium arsenide in terms of radio frequency performance, quality and reliability, and is easier to integrate CMOS radio frequency switches or other components. Therefore, the shipment volume of silicon germanium carbon components has increased dramatically in recent years, and the penetration rate in the MMIC LNA market is equivalent to that of gallium arsenide components. Infineon's silicon germanium carbon MMIC LNA has successfully entered MediaTek's multi-band multi-mode LTE public board recommendation list, and is expected to continue to increase its market share from the end of this year to next year.
As for PA, Mai Zhengqi believes that although gallium arsenide solutions are still the mainstream, CMOS PA is expected to rise in the low-end mobile phone market in the future due to its advantages in cost and functional integration. In addition, Infineon has included silicon germanium carbon LNA plus PA system package (SiP) or single-chip integration solution in the next-generation product blueprint to help mobile phone manufacturers optimize system volume while maintaining radio frequency performance.
Although LTE-A and 5G specifications have not yet been fully determined, there are rumors in the industry that mobile phone manufacturers may abandon integrated radio frequency solutions and switch to discrete designs in order to achieve high-speed and high-quality transmission performance. In this regard, Mai Zhengqi said that although some radio frequency chip manufacturers are currently studying more advanced gallium nitride (GaN) processes and improving radio frequency system functions through plug-ins, component integration is still the key to reducing costs and saving energy. Therefore, only after the communication standard is determined, the best design balance point can be found based on specification requirements.