Patent ID: 8446232

Claim:
A tunable RF filter device comprising a plurality of filter stages that are connected in series, each filter stage including: a filter stage input; a filter stage output; a filter stage ground; and one or more first transmission lines, each first transmission line being connected to at least two connection nodes, each connection node being additionally connected to: either the filter stage input, the filter stage output, or another of the one or more transmission lines; and one of a plurality of second transmission lines, each second transmission line being additionally connected to a switching means; where the switching means of each filter stage is configured to operate such that either each of the plurality of second transmission lines within that filter stage is provided an open circuit, or each of the plurality of second transmission lines within that filter stage is connected to the filter stage ground of that filter stage; where the plurality of filter stages comprises a first filter stage; each of the one or more transmission lines within the first filter stage is of about the same electrical length, which is denoted as L 1 ; each of the plurality of second transmission lines within the first filter stage is of about the same electrical length, which is denoted as L 2 ; and L 1 is about twice L 2 ; where the plurality of filter stages further comprises a second filter stage; each of the one or more transmission lines within the second filter stage is of the about same electrical length, which is denoted as L 3 ; each of the plurality of second transmission lines within the second filter stage is of about the same electrical length, which is denoted as L 4 ; L 3 is about L 2 ; and L 3 is about twice L 4 .