A Miniature UWB Filter with In-Band Interference Cancelation

This paper presents a design for a miniature filter that can be configured as either an ultra-wideband (UWB) filter or a UWB band filter with in-band rejection for interference cancelation. A microstrip filter with N resonators is integrated with N+1 lumped capacitors to effectively produce 2N+1 resonators. With the proper choice of the resonator dimensions and the lumped element capacitors values, the filter can be configured as UWB filter with an order of 2N+1 or as a filter, with a dual-band response having one band of order N+1 and the other band of order N, with an isolation guard band in-between to eliminate interference. EM theoretical and measured results are presented to verify the validity of the concept.