Passband filter combining resonators of a first type and resonators of a second type
According to the present disclosure, a passband filter is provided. The passband filter comprises a first connection, a second connection, and a third connection. One or more resonators of a first type are provided connected in series between the first connection and the second connection; and one or more resonators of a second type are provided connected from between the first connection and the second connection to the third connection. A radio-frequency front end module and wireless mobile device are also provided.
1. A passband filter comprising:
a first connection;
a second connection;
a third connection;
a first substrate;
a second substrate;
one or more resonators of a first type connected in series between the first connection and the second connection, the one or more resonators of the first type being disposed on the first substrate; and
one or more resonators of a second type connected from between the first connection and the second connection to the third connection, the one or more resonators of the second type being disposed on the second substrate.
2. The passband filter of claim 1 wherein each of the one or more resonators of the second type are connected in parallel from between the first connection and the second connection to the third connection.
3. The passband filter of claim 2 wherein one of the one or more resonators of the second type is connected to the third connection from between each of the one or more resonators of the first type connected in series.
4. The passband filter of claim 3 comprising n resonators of the second type and n+1 resonators of the first type.
5. The passband filter of claim 1 wherein the third connection is a ground connection.
6. The passband filter of claim 1 wherein each of the one or more resonators of the first type have a smooth frequency response below a resonant frequency of the resonator.
7. The passband filter of claim 6 wherein the one or more resonators of the first type are Lamb wave resonators.
8. The passband filter of claim 1 wherein each of the one or more resonators of the second type have a smooth frequency response above a resonant frequency of the resonator.
9. The passband filter of claim 8 wherein the one or more resonators of the second type are film bulk acoustic wave resonators.
10. The passband filter of claim 1 wherein the first substrate has a first surface, the one or more resonators of the first type being disposed on the first surface, and the second substrate has a second surface, the one or more resonators of the second type being disposed on the second surface, the first substrate and the second substrate being arranged such that the first surface faces the second surface.
11. The passband filter of claim 1 made by forming the one or more resonators of the first type on the first substrate, forming the one or more resonators of the second type on the second substrate, and subsequently either mounting the first substrate onto the second substrate or mounting the second substrate onto the first substrate.
12. The passband filter of claim 1 wherein one or both of the first substrate and the second substrate are silicon wafers.
13. The passband filter of claim 1 wherein the one or more resonators of the first type each have a piezoelectric layer of a first material, and wherein the one or more resonators of the second type each have a piezoelectric layer of a second material, the second material being different from the first material.
14. The passband filter of claim 13 wherein the first material is one of lithium niobate or lithium tantalate.
15. The passband filter of claim 13 wherein the second material is one of aluminum nitride, doped aluminum nitride, or zinc oxide.
16. A radio-frequency module comprising:
a packaging substrate configured to receive a plurality of devices; and
a die mounted on the packaging substrate, the die having a passband filter having a first connection, a second connection, a third connection, a first substrate, a second substrate, one or more resonators of a first type connected in series between the first connection and the second connection, the one or more resonators of the first type being disposed on the first substrate, and one or more resonators of a second type connected from between the first connection and the second connection to the third connection, the one or more resonators of the second type being disposed on the second substrate.
17. A wireless mobile device comprising:
one or more antennas; and
a radio-frequency module that communicates with the one or more antennas, the radio-frequency module having a die including a passband filter having a first connection, a second connection, a third connection, a first substrate, a second substrate, one or more resonators of a first type connected in series between the first connection and the second connection, the one or more resonators of the first type being disposed on the first substrate, and one or more resonators of a second type connected from between the first connection and the second connection to the third connection, the one or more resonators of the second type being disposed on the second substrate.