Band-pass Filter In The Wireless Communication System Research

As an essential component in modern wireless communication systems , RF bandpass filter has attracted more and more attention and got many achievements too .In this thesis , some research of the design methods and new structures and techniques of bandpass filter in wireless communication systems are proposed .The dissertation is classified into three parts stated as follows.Firstly ,based on the theory of SCALING method ,and with the aid of modern EDA software,we get a new design method of coupled-microstrip bandpass filter.With the collection of a series of templates,designer can choose the most suitable model from the templates by the algorithm brought forward in this thesis.Then,the ultimate design can be achieved with some simple transformations.Secondly, after introducing the main theory of SIR(stepped impedance resonator),a design method of taper-bandpass filter has been discussed .To get two attenuation poles in the stopband ,a new structure with spurline in the taper is proposed.The simulation result shows that this structure enhances the filter's performance as expected.Lastly, the theory and development of LTCC(low temperature co-fired ceram)technology is presented.Then a compact second-order LTCC bandpass filter with two finite transmission zeros is proposed.In the end ,a second-order bandpass filter designed from a modified-Chebyshev model is demonstrated,The second harmonic frequency can be suppressed with SIR technology being used.