The role of the filter can be summed up in four words: remove the false and retain the true, process the signal, and deal with the harmonics we don't need, leaving the signal we need.
The Internet devices we use must send cellular, Wi-Fi, Bluetooth, and GPS signals across multiple frequency bands while avoiding interference. With the rapid increase in the operating frequency of electronic equipment, the frequency of electromagnetic interference is also getting higher and higher, and the interference frequency usually reaches hundreds of megahertz, or even more than gigahertz. Because the higher the frequency of voltage or current, the easier it is to produce radiation, therefore, it is these interference signals with high frequencies that lead to the increasingly serious problem of radiated interference, a basic requirement of the filter used to solve radiated interference is to be able to attenuate these high-frequency interference signals greatly, this filter is the radio frequency interference filter, the effective filtering frequency range of the ordinary interference filter is kilohertz to tens of megahertz, and the effective filtering frequency range of the radio frequency interference filter is from thousands of hertz to more than gigahertz.
Analysis of the current situation and prospect forecast of the RF filter industry
There are four basic prototypes of RF filters, namely low-pass filters, high-pass filters, band-pass filters, and band-stop filters. Low-pass realizes that only low-frequency signals pass through, and high-frequency signals are suppressed. The characteristics of high pass and low pass are opposite, allowing high frequency to pass, suppressing low frequency, band pass and band resistance are respectively allowed to pass or suppress the frequency signal in the required frequency band, in radio frequency communication, the filter is used as a basic element, in order to ensure that the signal is pure that is not damaged by the interference signal, in navigation, radio broadcasting, television broadcasting, mobile phone communications, satellite communications, radar and many other fields have played a unique and important role. As of 2019, the market share of high-frequency filters is 49.59%, ranking first, and the market share of bandpass filters is 24.26%, ranking second.
The rapid growth of mobile wireless data and 4G LTE networks has led to a growing demand for new frequency bands and bands that can be combined through carrier aggregation to accommodate wireless traffic. While only about five frequency bands are used in 3G networks, LTE networks now use more than 40 frequency bands, and the number of bands will increase further with the arrival of 5G. This directly increases the market demand for RF filters.
In today's mobile environment, the number of frequency bands required for a single device is staggering, and this trend will only intensify with the advent of 5G. While supporting all frequency bands can cause interference problems, the problem can be solved with filters, without which the network simply cannot function. There are many types of filter structures, and in the future, it should be mainly in the form of microstrip and multi-layer structure, which is small in size, can withstand large power and low loss, which is the goal of filter progress. In recent years, RF filters have followed the rapid development of modern wireless communication technology, and the market value has increased year after year, reaching $4.095 billion in 2019. It is expected to continue to maintain a rapid upward trend for a long time in the future.
In 1917, American and German scientists respectively invented the LC filter, and the following year, the first multiplexing system in the United States appeared. In the 50s of the 20th century, passive filters became more and more mature. Since the 60s, due to the development of computer technology, integrated technology and material industry, the development of filters has reached a new level, and efforts have been made in the direction of low power consumption, high precision, small size, multi-function, stable reliability and low price, among which small size, multi-function, high precision, stability and reliability have become the main direction of attack after the 70s. Developed countries such as Europe and the United States have developed and developed various filter products earlier and the technology is more mature; China's extensive use of filters was in the late 50s, when it was mainly used for voice filtering and reporting path filtering.
After half a century of development, China's filter has been included in the international development pace in terms of development, production and application, but due to the lack of special research and development institutions, the integrated process and material industry can not keep up, so that the development and application of many new filters on the mainland and the international development of a certain distance; while Africa, the Middle East and other relatively backward regions, not only lack technology, but also slow development. As of 2019, the Asia-Pacific region ranked first with a market share of 37.88%, and North America ranked second with a market share of 30.67%.
Impact of COVID-19 on the RF filter industry
Since the outbreak of COVID-19 in early 2020, the virus has spread to all parts of the world, causing great harm to the global economy, and the impact of the epidemic varies from industry to industry. During the epidemic, governments around the world have introduced a series of measures to control the flow of people and reduce the occurrence of cross-infection, and many enterprises are unable to carry out normal production and operation. However, it is expected that the impact of COVID-19 on the global RF filter industry is only temporary, and it will continue to show its development vitality after the epidemic recovery.