San Jose, CA - October 17, 2018
Cavendish Kinetics RF MEMS Enable 5G in Mobile Handsets
5G is rapidly approaching. According to Strategy Analytics, the first 5G-enabled smartphones will be launched in 2019 and annual 5G smartphone volume will grow to 1.5BU by 2025. The advantages of 5G are significant. However, 5G requirements introduce difficult challenges for smartphone antenna and RF Front End (RFFE) designers. Cavendish Kinetics (CK) RF MEMS can help solve those challenges.
One facet of the 5G specification is eMBB (enhanced Mobile Broadband). eMBB defines 1 Gbps peak and 1.5 Mbps average data rates per user. Accomplishing these data rates requires wider bandwidth, aggregating higher frequencies, with more antennas.
The 5G standard includes frequencies up to 86GHz. However, most experts agree that smartphones will initially implement 5G in the sub 6GHz band. Unlike mm-wave, sub 6GHz frequencies have reasonable propagation characteristics. Sub 6GHz has better building penetration and does not require the smartphone to implement complicated beamforming techniques. In addition, there is already some harmonization of allocated world-wide 5G frequency spectrum between 3-6 GHz as seen in Table 1.
Table 1. World-Wide sub 6 GHz 5G spectrum allocation
That said, the antenna design of 5G smartphone supporting 600MHz to 6GHz frequencies will be very challenging. 5G requires support of 4x4 MIMO. As more antennas are packed into a smartphone, the average antenna volume decreases. In addition, a clear trend in smartphones is high screen to body ratios. Some of today’s LTE phones achieve a 90% ratio. Consumers will demand the same or better screen to body ratios in their 5G phones. The display presents a ground plane to RF radiation. Therefore, the gap in the bezel around the display is where the antennas reside. As the bezel shrinks, it squeezes antenna volume further. The result will be narrow band antennas with compromised efficiency. Even if dedicated antennas are used for higher frequencies, tuning will still be required. As such, tuning devices must maintain low loss and high linearity up to 6 GHz.
RF MEMS is the answer. CK MEMS are widely used in today’s smartphone applications and are designed to support all 5G sub 6GHz bands. Figure 1 shows good linearity of the CK MEMS tuner, as a function of capacitance across 500 MHz to 6 GHz.
Figure 1. Measured Capacitance vs. Frequency curves from 500 MHz to 6 GHz
CK’s RF MEMS performance advantage over traditional solid state technologies like SOI are well known in low band frequencies from 600MHz to 1GHz. CK’s RF MEMs performance advantage in the new 5G bands is also significant, allowing designers to maximize radiated efficiency in the 3-6GHz spectrum. This improves total radiated power (TRP) and total isotropic sensitivity (TIS), thereby enhancing 5G performance.
For smartphone antenna designers, 5G challenges include wider bandwidth, high frequency of operation, and more antennas within a reduced space. CK RF MEMS antenna tuners help solve these challenges through low loss, high efficiency and high linearity.