Acoustic filter with improved reflectivity
AssigneeRF360 Singapore Pte. Ltd.
InventorsSimone Colasanti, Samir Tazarine, Robert Koch, Franz Kubat
Life of this patent
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Abstract
A filter circuit comprises a main operating unit (MU) arranged in the series signal line providing most of the filter function of the filter circuit. A micro acoustic last series resonator (RLs) as a last element of the main operating unit in the series signal line is prone to excite a spurious mode that is damped with a final series capacitance (CEs) circuited between the last element and the antenna terminal (AT).
Claims12
A filter circuit that provides a pass band, comprising:
- a series signal line that connects a first terminal and an antenna terminal;
- a main operating unit arranged in the series signal line providing a filter function of the filter circuit;
- a micro acoustic last series resonator that is a last element in the series signal line and part of the main operating unit;
- and
- a final series capacitance circuited between the last element and the antenna terminal, wherein the main operating unit ends with a last node and a last parallel branch connected to the last node, wherein a parallel micro-acoustic resonator is arranged in the last parallel branch, and wherein the last node is directly connected to the final series capacitance and the final series capacitance is directly connected to the antenna terminal.
A filter circuit that provides a pass band, comprising:
- a series signal line that connects a first terminal and an antenna terminal;
- a main operating unit arranged in the series signal line a filter function of the filter circuit;
- a micro acoustic last series resonator that is a last element in the series signal line and part of the main operating unit;
- and
- a final series capacitance circuited between the last element and the antenna terminal;
- wherein the final series capacitance is directly connected the antenna terminal.
A filter circuit that provides a pass band, comprising:
- a series signal line that connects a first terminal and an antenna terminal;
- a main operating unit arranged in the series signal line a filter function of the filter circuit;
- a micro acoustic last series resonator that is a last element in the series signal line and part of the main operating unit;
- a final series capacitance circuited between the last element and the antenna terminal;
- a further parallel branch comprising an additional parallel capacitance;
- and
- an additional series coil parallel to the final series capacitance.
Dependencies are inferred from the claim text.