Reserch And Applications Of High Squareness Ratio Cross-coupled Filter

With the development of national information technology, china is ongoing large-scale deployment of broadband mobile communication networks. Due to the limited spectrum resources, interferences of adjacent-band between diffrent systems are growing. How to reduce out of band interference and improve in-band S/N(signal to noise ratio),and how to improve communication quality has become important issues of the communications carriers and equipment manufacturers.Mobile communication devices need a large number of high-performance microwave filters, this filters must have high rectangular coefficient (ie, a steeper band rejection), low insertion loss in-band and equalizer features of group delay in-band. Used the cross-coupling technology in design work of filters, And artificial introduce transmission zeros of specific frequency; it can meet these performance requirements and reduce the order of filter.In this paper, an integrated approach of cross-coupled filter has general Chebyshev filtering characteristics was researched; the theoretical accuracy of the calculation was verified via simulation.Based on the theoretical study, a series based on Matlab filter integrated program was Prepared, and conducted CDMA, GSM and3GHz band bandpass filters integrated computing and research,the computing results show that the cross-coupling technology can significantly improve filter performance.Based on the results of integrated design, a WCDMA band filter has designed and simulation verification using HFSS, the results from simulation and comprehensive response has obtained are very close to the theoretical calculated, proved the effectiveness of integrated design approach of filter.At last of the paper, the major works of this paper is summarized. This part of the paper also explains the practical value to the works of comprehensive technology and simulation methods in microwave filter design.