SOLIDLY-MOUNTED TRANSVERSELY-EXCITED BULK ACOUSTIC RESONATOR SPLIT LADDER FILTER
A filter device is provided that includes a first chip comprising a first IDT of a first solidly-mounted resonator on a surface of a first piezoelectric layer. The IDT including a first plurality of interleaved fingers having a first thickness. A first acoustic reflector is sandwiched between the first piezoelectric layer and a first base. The filter device includes a second chip having a second IDT of a second solidly-mounted resonator on a surface of a second piezoelectric layer. The second IDT includes a second plurality of interleaved fingers having a second thickness that is different from the first thickness. A second acoustic reflector is sandwiched between the second piezoelectric layer and a second base. An electrical connection is provided between the first IDT and the second IDT.
1 . A filter device comprising:
a first chip comprising:
a first interdigital transducer (IDT) of a first solidly-mounted resonator on a surface of a first piezoelectric layer, the first IDT including a first plurality of interleaved fingers having a first thickness, and
a first acoustic reflector sandwiched between the first piezoelectric layer and a first base,
a second chip comprising:
a second IDT of a second solidly-mounted resonator on a surface of a second piezoelectric layer, the second IDT including a second plurality of interleaved fingers having a second thickness that is different from the first thickness of the first plurality of interleaved fingers, and
a second acoustic reflector sandwiched between the second piezoelectric layer and a second base; and
an electrical connection between the first IDT and the second IDT.
2 . The filter device of claim 1 , wherein the first piezoelectric layer has a first thickness and the second piezoelectric layer has a second thickness different from the first thickness.
3 . The filter device of claim 1 , wherein the first and second acoustic reflectors each comprise alternating low acoustic impedance and high acoustic impedance layers respectively.
4 . The filter device of claim 3 , wherein the first acoustic reflector and the second acoustic reflector differ in one or more of: a number of layers, a thickness of one or more layers, an ordered sequence of the high and low acoustic impedance layers, a material of the high acoustic impedance layers, and a material of the low acoustic impedance layers.
5 . The filter device of claim 1 , wherein the first chip, the second chip, and the electrical connection collectively form components of a ladder filter circuit.
6 . The filter device of claim 5 , wherein the electrical connection is one of one or more electrical connections, and wherein an inductance of one or more of the electrical connections lowers a frequency of a shunt resonator in the ladder filter circuit.
7 . The filter device of claim 5 , wherein:
the first solidly-mounted resonator is a shunt resonator in the ladder filter circuit, and
the second solidly-mounted resonator is a series resonator in the ladder filter circuit.
8 . The filter device of claim 1 , wherein the first chip comprises a first dielectric layer that is disposed over and between the first plurality of interleaved fingers of the first IDT, and the second chip comprises a second dielectric layer that is disposed over and between the second plurality of interleaved fingers of the second IDT.
9 . The filter device of claim 1 , wherein at least one of the first and second solidly-mounted resonators is a solidly-mounted transversely-excited film bulk acoustic resonator.
10 . The filter device of claim 1 , wherein a pitch between adjacent fingers of the first plurality of interleaved fingers of the first IDT is different than the pitch between adjacent fingers of the second plurality interleaved fingers of the second IDT.
11 . The filter device of claim 1 , wherein a first ordered sequence of the first chip is different from a second ordered sequence of the second chip.
12 . The filter device of claim 1 , wherein an orientation of a crystalline axes of the first piezoelectric layer is different from an orientation of a crystalline axes of the second piezoelectric layer.
13 . The filter device of claim 1 , wherein the first solidly-mounted resonator is part of a transmit filter and the second solidly-mounted resonator is part of a receive filter.
14 . The filter device of claim 1 , further comprising a circuit card interconnecting the first chip and the second chip, and wherein the circuit card comprises the electrical connection between the first chip and the second chip.
15 . A filter device comprising:
a first chip comprising:
a first interdigital transducer (IDT) of a first resonator on a surface of a first piezoelectric layer, and
an acoustic reflector sandwiched between the first piezoelectric layer and a first base;
a second chip comprising:
a second IDT of a second resonator on a surface of a second piezoelectric layer; and
a circuit card interconnecting the first chip and the second chip, wherein the circuit card includes an electrical connection between the first IDT of the first chip and the second IDT of the second chip.
16 . The filter device of claim 15 , wherein at least one of the first piezoelectric layer and the second piezoelectric layer are respectively a single-crystal piezoelectric material.
17 . The filter device of claim 15 , wherein a thickness of interleaved fingers of the first IDT is different from a thickness of interleaved fingers of the second IDT.
18 . The filter device of claim 15 , wherein the first piezoelectric layer has a first thickness and the second piezoelectric layer has a second thickness different from the first thickness.
19 . The filter device of claim 15 , wherein the first resonator comprises a transversely excited solidly-mounted resonator and the second resonator comprises a floating-diaphragm transversely excited resonator.
20 . The filter device of claim 15 , wherein:
the first chip, the second chip, and the electrical connection collectively form components of a ladder filter circuit,
the electrical connection is one of one or more electrical connections and wherein an inductance of one or more of the electrical connections lowers a frequency of a shunt resonator in the ladder filter circuit, and
the first resonator is a shunt resonator in the ladder filter circuit, and the second resonator is a series resonator in the ladder filter circuit.