Saw device with improved thermal management
Aspects herein include minimizing hot spots on a filter chip by creating thermal radiators using mechano-acoustic structures and connection circuitry. A gradual increase of metal to wafer relation provides better heat dissipation and heat sinking. Shunt lines of a ladder type arrangement of SAW resonators comprise a broadened section. Resonators that are subsequent to each other in the series signal line are connected via a common busbar extending over a length of subsequent series resonators. A lateral extension of the common busbars represents a first section of a respective shunt line. A first shunt line section between a node and the parallel resonator of a shunt line comprises a section that is broader than the common busbar, the broadened section extending over the width of the parallel resonator. The first reflector of the parallel resonator that faces the laterally adjacent series resonator is formed from the broadened section.
1. A SAW filter device, comprising:
a series resonator arranged in a series signal line;
a shunt line connected to a node situated in the series signal line relative to the series resonator; and
a parallel resonator arranged in the shunt line, wherein:
the shunt line comprises a broadened section located between the series resonator and the parallel resonator, and
a busbar of the series resonator and the broadened section are formed from a same metallization.
2. The SAW filter device of claim 1 , wherein the parallel resonator comprises a reflector formed from the same metallization as the busbar of the series resonator and the broadened section.
3. The SAW filter device of claim 2 , wherein the reflector is formed at least in part from the broadened section.
4. The SAW filter device of claim 2 , wherein the reflector is positioned between the series resonator and the parallel resonator.
5. The SAW filter device of claim 1 , wherein the series resonator is a first series resonator, the SAW filter device further comprising a second series resonator arranged in the series signal line, wherein the first series resonator and the second series resonator are connected via a common busbar extending over a length of the first series resonator and the second series resonator.
6. The SAW filter device of claim 5 , wherein a lateral extension of the common busbar forms a first section of the shunt line.
7. The SAW filter device of claim 6 , wherein the lateral extension of the common busbar forms a busbar of the parallel resonator.
8. The SAW filter device of claim 1 , wherein a busbar of the parallel resonator is formed from the same metallization as the busbar of the series resonator and the broadened section.
9. The SAW filter device of claim 1 , wherein the parallel resonator has a length measured in a longitudinal direction corresponding to a wave propagation direction and a width measured in a transversal direction.
10. The SAW filter device of claim 1 , further comprising a plurality of series resonators arranged in the series signal line, the plurality of series resonators including the series resonator,
wherein the plurality of series resonators are aligned one below the other in a line parallel to a transversal direction associated with a width of the plurality of series resonators,
wherein reflectors of the plurality of series resonators are formed from a strip-type metallization extending over a combined length of the plurality of series resonators.
11. The SAW filter device of claim 1 , further comprising a plurality of series resonators arranged in the series signal line, the plurality of series resonators including the series resonator,
wherein the plurality of series resonators are arranged between a first node and a last node in the series signal line and are each cascaded by a series connection of two single resonators, and
wherein respective reflectors of the plurality of series resonators are common to the two single resonators and extend over a total width of the two single resonators.
12. The SAW filter device of claim 1 , wherein the series resonator is next to an input/output (I/O) terminal, and wherein a reflector of the series resonator, the busbar of the series resonator, and the I/O terminal are formed from the same metallization.
13. The SAW filter device of claim 1 , further comprising a plurality of series resonators arranged in the series signal line, the plurality of series resonators including the series resonator,
wherein each series resonator of the plurality of series resonators is cascaded by a series connection of a respective pair of single resonators, and
wherein reflectors of each respective pair of single resonators are electrically isolated from each other.
14. The SAW filter device of claim 13 , wherein the SAW filter device is a transmit filter, wherein an input/output (I/O) terminal of the transmit filter is a transmit terminal, and wherein a second series resonator that is next to the transmit terminal is un-cascaded and has a length that is at least a twofold length of one or more of the plurality of series resonators of the transmit filter.