The rapid growth in mobile wireless data and 4G LTE networks has created an ever-increasing need for
new frequency bands, and combining bands through carrier aggregation, to accommodate wireless
traffic. Connected devices must transmit cellular signals, Wi-Fi, Bluetooth and GPS across multiple
frequency bands while avoiding interference. 4G mobile systems is characterized by a horizontal
communication model, where such different access technologies as cellular, cordless, wireless LAN type
systems, short-range wireless connectivity, and wired systems will be combined on a common platform
to complement each other in the best possible way for different service requirements and radio
environments
This is where filters come in. Best-in-class RF filter receive insertion loss allows engineers to achieve
optimum receiver sensitivity. It allow desired frequencies while rejecting unwanted ones. Multiplexers
combine multiple filters into a single device, which helps designers save space, simplify design, and meet
performance requirements, while avoiding interference. RF filters have become more abundant in radio
front ends. Filters limit RF signals within specific frequencies to prevent interference between wireless
devices, wireless bands, and network equipment. For wireless communications, satellite, and broadcast
radio applications from 100 MHz to 5 GHz, most filters are manufactured using SAW (Surface Acoustic
Wave), BAW (Bulk Acoustic Wave) and FBAR (Film Bulk Acoustic Resonator) technologies.
In a SAW filter, the electrical input signal converts to a horizontal acoustic wave by interleaving metal
interdigital transducers (IDTs) deposited on a piezoelectric substrate, such as quartz or lithium tantalite.
Standard filter applications up to 1.9 GHz use SAW filters – including GSM, CDMA, 3G, and some 4G
wireless standards. In a BAW filter, the acoustic wave propagates vertically. BAW resonators use quartz
crystal substrates and top and bottom metal patches to excite the acoustic waves. These acoustic waves
are confined within the film. The resonant frequency is set by the thickness of the film and mass of
electrodes. BAW technology creates optimal narrowband filters with steep skirts and excellent rejection.
BAW delivers these acoustic benefits at frequencies above 1.5 GHz, making it a complementary
technology to SAW.
4G wireless technology offers higher data rates and the ability to roam across multiple heterogeneous
wireless networks. As the spectrum becomes more crowded with devices such as smartphones and
tablets. We might immediately think of smartphones, but the same is true of shark fins mounted atop a
car’s roof, cellular base stations, radar and communications systems, and industrial, scientific or medical
applications connected to the Internet of Things (IoT). Users struggle to achieve 4G coverage with
minimized dead spots and dropped calls. Transmit output power, antenna gain and receiver sensitivity
are important in achieving optimal signal coverage. Radio receiver sensitivity is the level of noise
generated within or outside the radio receiver.
The exponential growth of data traffic, coupled with the crowded frequency spectrum, increases
coexistence and communication challenges with our everyday mobile devices. This is driving explosive
growth in the RF filter market, and driving the need for more sophisticated filter technologies.
Fortunately, RF filter technology is continuously evolving – filters are becoming smaller, more
integrated, and more efficient. Therefore with a history of manufacturing and developing new,
advanced filter technology solutions, are poised to meet the needs of the busy wireless technology
market.