Acoustic Resonator Cascade
An apparatus is disclosed for an acoustic resonator cascade. In example aspects, the apparatus includes at least one filter circuit. The at least one filter circuit includes a substrate, a first resonator cascade, and a second resonator cascade. The substrate has a surface including a first axis and a second axis. The first resonator cascade has multiple acoustic resonators and is disposed on the surface of the substrate in a first column along the first axis. The second resonator cascade has multiple acoustic resonators and is disposed on the surface of the substrate in a second column along the first axis. A first gap extends along the second axis between the first resonator cascade and the second resonator cascade. A second gap extends along the second axis between the first resonator cascade and the second resonator cascade. The first gap is different from the second gap.
1 . An apparatus comprising:
at least one filter circuit comprising:
a substrate comprising a surface having a first axis and a second axis;
a first resonator cascade of multiple acoustic resonators disposed on the surface of the substrate in a first column along the first axis; and
a second resonator cascade of multiple acoustic resonators disposed on the surface of the substrate in a second column along the first axis,
a first gap extending along the second axis between the first resonator cascade of multiple acoustic resonators and the second resonator cascade of multiple acoustic resonators, and
a second gap extending along the second axis between the first resonator cascade of multiple acoustic resonators and the second resonator cascade of multiple acoustic resonators, the first gap different from the second gap.
2 . The apparatus of claim 1 , wherein:
the first resonator cascade of multiple acoustic resonators comprises a first acoustic resonator and a second acoustic resonator;
the second resonator cascade of multiple acoustic resonators comprises a third acoustic resonator and a fourth acoustic resonator;
the first gap extends between the first acoustic resonator and the third acoustic resonator; and
the second gap extends between the second acoustic resonator and the fourth acoustic resonator.
3 . The apparatus of claim 2 , wherein:
the first acoustic resonator comprises at least one interdigital transducer (IDT) and at least one reflector; and
the third acoustic resonator comprises at least one interdigital transducer (IDT) and at least one reflector.
4 . The apparatus of claim 1 , wherein:
the multiple acoustic resonators of the first resonator cascade comprise piezoelectric material that forms at least part of a piezoelectric layer of the substrate and that provides the surface of the substrate; and
the multiple acoustic resonators of the second resonator cascade comprise the piezoelectric material that forms at least part of the piezoelectric layer of the substrate.
5 . The apparatus of claim 1 , wherein:
at least one acoustic resonator of the multiple acoustic resonators of the first resonator cascade comprises at least part of a double-mode surface acoustic wave (SAW) (DMS) filter; and
at least one acoustic resonator of the multiple acoustic resonators of the second resonator cascade comprises at least part of another DMS filter.
6 . The apparatus of claim 1 , wherein:
the multiple acoustic resonators of the first resonator cascade are coupled together in series; and
the multiple acoustic resonators of the second resonator cascade are coupled together in series.
7 . The apparatus of claim 1 , wherein:
the at least one filter circuit comprise a first filter circuit and a second filter circuit;
the first filter circuit comprises the first resonator cascade;
the second filter circuit comprises the second resonator cascade; and
the first axis is substantially orthogonal to the second axis.
8 . The apparatus of claim 1 , wherein:
the multiple acoustic resonators of the first resonator cascade have a quantity of “A” acoustic resonators, with “A” representing an integer greater than one;
the multiple acoustic resonators of the second resonator cascade have a quantity of “B” acoustic resonators, with “B” representing an integer greater than one; and
multiple gaps extend along the second axis between the first resonator cascade of multiple acoustic resonators and the second resonator cascade of multiple acoustic resonators, the multiple gaps including the first gap and the second gap.
9 . The apparatus of claim 8 , wherein the quantity “A” is different from the quantity “B.”
10 . The apparatus of claim 8 , wherein the quantity “A” is equal to the quantity “B.”
11 . The apparatus of claim 8 , wherein a size of the multiple acoustic resonators of the first resonator cascade is different from a size of the multiple acoustic resonators of the second resonator cascade.
12 . The apparatus of claim 8 , wherein a size of the multiple acoustic resonators of the first resonator cascade is substantially the same as a size of the multiple acoustic resonators of the second resonator cascade.
13 . The apparatus of claim 8 , wherein:
the multiple gaps comprise a smallest gap and multiple other gaps;
the multiple gaps have a quantity of “N,” with “N” representing an integer greater than one; and
respective amounts by which respective gaps of the multiple other gaps are larger than the smallest gap are based on:
(
M
×
2
×
Pitch
)
/
N
,
where:
“Pitch” corresponds to a pitch of at least one interdigital transducer of the multiple acoustic resonators of the first resonator cascade or of the multiple acoustic resonators of the second resonator cascade; and
“M” corresponds to [0, 1, 2, . . . , (N−1)].
14 . The apparatus of claim 8 , wherein:
the multiple acoustic resonators of the first resonator cascade have a common alignment relative to the second axis; and
the multiple acoustic resonators of the second resonator cascade have multiple alignments relative to the second axis that differ from each other to create the multiple gaps.
15 . The apparatus of claim 8 , wherein:
the multiple acoustic resonators of the first resonator cascade have at least one alignment relative to the second axis that differs from at least one other alignment thereof to create at least one gap of the multiple gaps; and
the multiple acoustic resonators of the second resonator cascade have at least one alignment relative to the second axis that differs from at least one other alignment thereof to create at least one other gap of the multiple gaps.
16 . The apparatus of claim 1 , further comprising:
a radio-frequency front-end comprising the at least one filter circuit.
17 . The apparatus of claim 16 , further comprising:
a wireless interface device comprising the radio-frequency front-end;
a display screen; and
at least one processor operatively coupled to the display screen and at least a portion of the wireless interface device, the at least one processor configured to present one or more graphical images on the display screen based on one or more wireless signals communicated using the at least one filter circuit of the wireless interface device.
18 . An apparatus comprising:
at least one filter circuit comprising:
a substrate comprising:
a surface having a first axis and a second axis; and
a backside that is opposite the surface;
a first resonator cascade of multiple acoustic resonators disposed on the surface of the substrate in a first column along the first axis;
a second resonator cascade of multiple acoustic resonators disposed on the surface of the substrate in a second column along the first axis, the second column spaced apart from the first column along the second axis; and
means for reducing at the second resonator cascade interference from bulk wave signaling that emanates from the first resonator cascade and reflects off the backside of the substrate.
19 . The apparatus of claim 18 , wherein the means for reducing comprises:
means for reducing at the first resonator cascade interference from bulk wave signaling that emanates from the second resonator cascade and reflects off the backside of the substrate.
20 . A method of manufacturing at least one filter circuit, the method comprising:
providing a substrate comprising a surface having a first axis and a second axis;
disposing a first resonator cascade comprising multiple acoustic resonators on the surface of the substrate in a first column along the first axis;
disposing a second resonator cascade comprising multiple acoustic resonators on the surface of the substrate in a second column along the first axis;
forming a first gap that extends along the second axis between at least one acoustic resonator of the first resonator cascade and at least one acoustic resonator of the second resonator cascade; and
forming a second gap that extends along the second axis between at least one other acoustic resonator of the first resonator cascade and at least one other acoustic resonator of the second resonator cascade, the first gap different from the second gap.