Patent ID: 8217657

Claim:
An impedance-transforming diplex filter, comprising: a first impedance-transforming filter having a first transmission frequency range and a first cut-off frequency range; a second impedance-transforming filter having a second transmission frequency range and a second cut-off frequency range, said first and second transmission frequency ranges being separate from each other and said first and second cut-off frequency ranges being separate from each other; each of said first and second impedance-transforming filters comprising a plurality of shunts and a plurality of series elements; a connection node that couples one of the series elements of said first impedance-transforming filter with one of the series elements of said second impedance-transforming filter, as coupled series elements; each of said coupled series elements being formed as a parallel resonance circuit; and the parallel resonance circuit forming the coupled series element of the first impedance-transforming filter having a predetermined reactance in a midband of said first transmission frequency range and a parallel resonance in a midband of said first cut-off frequency range, and the parallel resonance circuit forming the coupled series element of the second impedance-transforming filter having a predetermined reactance in a midband of the second transmission frequency range and a parallel resonance in a midband of the second cut-off frequency range.