RF filter
An RF filter is disclosed. In an embodiment, the RF filter includes series-interconnected basic elements, each basic element having an electroacoustic resonator and impedance converters interconnected in series between the basic elements, wherein the impedance converters are impedance inverters and/or admittance inverters, and wherein the resonators of the basic elements are either only series resonators or only parallel resonators.
1. An RF filter comprising:
four capacitive elements connected in series on a signal path;
six resonators elements, each resonator element connected between the signal path and ground such that two of said six resonators are coupled to the signal path between a first and second of said four capacitive elements, two of said six resonators are coupled to the signal path between the second and a third of said four capacitive elements, and two of said six resonators are coupled to the signal path between the third and a fourth of said four capacitive elements;
six switches, each of said six switches coupled to a respective one of said six resonator elements between the signal path and ground;
an inductive element coupled in parallel to the second and third capacitive elements.
2. The RF filter according to claim 1 wherein the RF filter is formed in a multilayer module wherein the capacitive elements and at least a portion of the signal line is formed in a first layer.
3. The RF filter according to claim 2 wherein the switches are formed in the first layer.
4. The RF filter according to claim 2 wherein the resonator elements are formed in a second layer.
5. The RF filter according to claim 2 wherein inductive element is connected to the multilayer module.
6. The RF filter according to claim 2 wherein the capacitive elements are MIM capacitors.
7. The RF filter according to claim 1 wherein the capacitive elements are MIM capacitors.