Stepwise switched filter
First Claim
1. A resonator structure including a transmission line resonator and a regulating element with which the specific impedance of said resonator structure and, thereby, the resonating frequency of the transmission line resonator can be changed in a stepwise manner, wherein, said regulating element comprises a switch which has at least three states that set at least two alternatively selectable current paths with different impedances, each said state corresponding to a value of the specific impedance of the resonator structure.
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Accused Products
Abstract
The invention relates to a resonator structure and radio frequency filter in which the resonating frequency of a transmission line resonator can be switched in a stepwise manner between at least three values. The switching is implemented as follows: a regulating element including a switch that has at least three states is arranged in connection with the resonator. The three states of the switch correspond to different values of the specific impedance and, hence, the resonating frequency of the transmission line resonator. The regulating element is in accordance with a known arrangement: it may be e.g. a coupling element formed of a strip line on the surface of a low-loss substrate or ceramic, or a side circuit including a capacitive and inductive element, coupled to the resonator. In the former example the switch is open in its first state, in its second state it grounds one end of the coupling element directly and in its other states it grounds the end of the coupling element through differently dimensioned transmission lines. In the latter implementation the switch is open in its first state, in its second state it forms at the side circuit a capacitive-inductive coupling in series and in its third state it bypasses the inductive element.
68 Citations
15 Claims
- 1. A resonator structure including a transmission line resonator and a regulating element with which the specific impedance of said resonator structure and, thereby, the resonating frequency of the transmission line resonator can be changed in a stepwise manner, wherein, said regulating element comprises a switch which has at least three states that set at least two alternatively selectable current paths with different impedances, each said state corresponding to a value of the specific impedance of the resonator structure.
- 11. A radio frequency filter comprising at least two resonators of which at least one resonator includes a transmission line resonator and a regulating element with which the specific impedance of said resonator and, hence, the resonator'"'"'s resonating frequency can be changed in a stepwise manner, characterized in that said regulating element comprises a switch which has at least three states that set at least two alternatively selectable current paths with different impedances, each said state corresponds to a different value of the specific impedance of the resonator structure.
Specification