In modern telecommunication equipment and various control systems, the filters are extremely widely used. Among all electronic components, the most used and most complicated technology is the filter. The advantages and disadvantages of the filter directly determine the performance of the product. Therefore, the research and production of the filters had always been valued by various countries, and various filters such as RC active filter, digital filter, switched capacitor filter and charge transfer device were made, which reflected the rapid development of the device.
By the late 1970s, the monolithic integration of the above several filters had been developed and applied. In the 1980s, we worked on the research of various new types of filters, striving to improve performance and gradually expand the range of applications. From the 1990s to the present, it is mainly devoted to the application of various types of filters to the research and development of various products. Of course, the research on the filter itself is still going on.