Synthesis And Design Of Filter With Z-Transform Technique

With the rapid development of communication technologies, the current wide- band communications can no longer satisfy people's communications needs. Stimulated by strong demand,in recent years, national and international experts raised a number of new wideband filter structure and design theory. However, the design of these filters, some are no synthesis theory, and some only based on the traditional narrow-band filter design theory and revise to be carried out a synthesis theory.The z Transform technique of this article is an new approach away from the traditional narrow-band filter design ideas, According to system function obtained from the characteristic of distribution parameters ,using discrete time-domain technique to obtain the z domain system function. Using the periodic structure basic unit consisting of quarter-wavelength short-circuited lines and half-wavelength connected lines to realize the filtering properties of system function. Obtained the various parts of the characteristic impedance after the filter is optimized calculation, and then adjusted according to the formula calculation and simulation you can get the physical size of the filter. This method has the following characteristics: This method has the following characteristics:(1)Inherited the basic design ideas of filters with using discrete time-domain, And proposed new ideas that making the system function from the distributed parameter circuit characteristics at first ; (2) Received periodic circuit structure is very practical circuit structure has a certain degree of regularity, clearly defining the filter series, which is the traditional method of discrete time-domain techniques can not get; (3) As the actual circuit structure of the certainty, it is very easy to optimize the calculation;(4) Optimized characteristic impedance difference from the actual structure will not be great, relatively easy to achieve .At last, in this paper use Synthesis method of Filter with Z-Transform Technique to design Low-pass, wideband, dual band-pass filters.