Microstrip Filtering Structure with Optimized Group-Delay Response for Wireless Communications

摘要

In this paper the design of a filtering structure with improved group-delay characteristic in microstrip technology is presented. This improvement is achieved by using pairs of equalization poles. In addition, an improved selectivity with respect to the adjacent channels is achieved by introducing two attenuation poles in the stop-band, one on each side of the pass-band. As a design example, a sixth-order quasi-elliptic filter with an in-band Chebyshev response, having two prescribed attenuation poles and two optimized group-delay equalization poles is designed, simulated, fabricated and tested. The measured characteristics of the experimental model are found to be in good agreement with the results anticipated through electromagnetic-field simulation. In a similar way, filters acting as equalization circuits can also be obtained using a slightly different optimization procedure, in order to improve the overall group-delay of a specified communication system.