Patent ID: 8179211

Claim:
A RF filter comprising: at least one substrate, a first sub-filter on the substrate comprising a series resonator and a first parallel resonator in a first parallel branch, a second parallel resonator in a second parallel branch, and a third parallel resonator in a third parallel branch, the parallel branches being connected to a signal path comprising the series resonator; a second sub-filter comprising a dual-mode surface wave elements filter (DMS SAW), connected in series to the first sub-filter in the signal path, a housing comprising a base plate comprising: at least one dielectric or nonconductive layer, a plurality of internal housing contacts on the base plate connected to terminal surfaces on the substrate, and a plurality of external housing contacts on an underside of the base plate, the external housing contacts being connected to the internal housing contacts via lines, the number of external housing contacts being less than the number of internal housing contacts, at least two separate lines on the base plate or in the base plate for connecting ground terminals of the first parallel resonator and of the second sub-filter to at least two different external housing contacts, wherein the ground terminal of the first parallel resonator is contacted directly by via-holes without additional wiring to a first external housing contact of the number of external housing contacts, wherein the ground terminal of the first parallel resonator and a ground terminal of the second parallel resonator are separate from one another and are connected to the first external housing contact, and wherein a ground terminal of the third parallel resonator and the ground terminals of the second sub-filter are connected to a second external housing contact of the number of external housing contacts.