US 12,068,737 B2
Acoustic filter with improved reflectivity
Simone Colasanti, Munich (DE); Samir Tazarine, Munich (DE); Robert Koch, Munich (DE); and Franz Kubat, Munich (DE)
Assigned to RF360 Singapore Pte. Ltd., Singapore (SG)
Appl. No. 17/297,906
Filed by RF360 SINGAPORE PTE. LTD., Republic Plaza (SG)
PCT Filed Dec. 13, 2019, PCT No. PCT/EP2019/085086
§ 371(c)(1), (2) Date May 27, 2021,
PCT Pub. No. WO2020/126909, PCT Pub. Date Jun. 25, 2020.
Claims priority of application No. 10 2018 132 881.8 (DE), filed on Dec. 19, 2018.
Prior Publication US 2022/0045663 A1, Feb. 10, 2022
Int. Cl. H03H 9/54 (2006.01); H03H 9/02 (2006.01); H03H 9/17 (2006.01); H03H 9/56 (2006.01)
CPC H03H 9/542 (2013.01) [H03H 9/02102 (2013.01); H03H 9/02834 (2013.01); H03H 9/17 (2013.01); H03H 9/568 (2013.01)] 12 Claims
OG exemplary drawing
 
1. 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.