Surface acoustic wave filter and filter device
View Patent ↗A surface acoustic wave filter includes series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion. This surface acoustic wave filter satisfies conditions expressed as: 1×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6 where Cop is the electrostatic capacitance of the parallel-arm resonators, Cos is the electrostatic capacitance of the series-arm resonators, f 0 is the center frequency, and R is the nominal impedance.
1. A surface acoustic wave filter comprising
series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
wherein the center frequency f 0 is in the 5 GHz band.
2. The surface acoustic wave filter as claimed in claim 1 , wherein the ratio Cop/Cos of the electrostatic capacitance Cop to the electrostatic capacitance Cos is 0.5.
3. The surface acoustic wave filter as claimed in claim 1 , wherein at least comb-like electrodes in the series-arm resonators and the parallel-arm resonators are covered with a dielectric film.
4. The surface acoustic wave filter as claimed in claim 1 , wherein the series-arm resonators and the parallel-arm resonators are connected to form a four-stage structure.
5. A surface acoustic wave filter comprising
series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1.3×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
wherein the center frequency f 0 is in the 5 GHz band.
6. A surface acoustic wave filter comprising
series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1.6×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦2.9×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance.
7. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is mounted by a wire bonding technique,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1.6×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦2.9×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal terminal connected to signal electrodes of the surface acoustic wave filter with one bonding wire, and
the bonding wire having an inductance Li (nH) that satisfies conditions expressed as:
0.7≦Li≦1.3.
8. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is flip-chip mounted,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal line formed by a microstrip line, and
the microstrip line having an inductance Li (nH) that satisfies conditions expressed as:
0.7≦Li≦1.3.
9. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is flip-chip mounted,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1.3×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal line formed by a microstrip line, and
the microstrip line having an inductance Li (nH) that satisfies conditions expressed as:
0.7≦Li≦1.3.
10. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is flip-chip mounted,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1.6×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦2.9×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal line formed by a microstrip line, and
the microstrip line having an inductance Li (nH) that satisfies the conditions expressed as:
0.7≦Li≦1.3.
11. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is mounted by a wire bonding technique,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal terminal connected to signal electrodes of the surface acoustic wave filter with one bonding wire, and
the bonding wire having an inductance Li (nH) that satisfies conditions expressed as:
0.7≦Li≦1.3
wherein the ratio Cop/Cos of the electrostatic capacitance Cop to the electrostatic capacitance Cos is 0.5.
12. The filter device as claimed in claim 11 , wherein at least comb-like electrodes in the series-arm resonators and the parallel-arm resonators are covered with a dielectric film.
13. The filter device as claimed in claim 11 , wherein the series-arm resonators and the parallel-arm resonators are connected to form a four-stage structure.
14. The filter device as claimed in claim 11 , wherein the package is made of ceramics.
15. A filter device comprising:
a surface acoustic wave filter; and
a package to which the surface acoustic wave filter is mounted by a wire bonding technique,
the surface acoustic wave filter including series-arm resonators and parallel-arm resonators that are connected in a ladder-like fashion,
the surface acoustic wave filter satisfying conditions expressed as:
1×10 6 ≦4π 2 f 0 2 R 2 CopCos ≦3.1×10 6
where Cop (pF) is an electrostatic capacitance of the parallel-arm resonators, Cos (pF) is an electrostatic capacitance of the series-arm resonators, f 0 (GHz) is a center frequency, and R is a nominal impedance,
the package having a signal terminal connected to signal electrodes of the surface acoustic wave filter with one bonding wire, and
the bonding wire having an inductance Li (nH) that satisfies conditions expressed as:
0.7≦Li≦1.3
wherein the center frequency f 0 is in the 5 GHz band.