MULTI-CAVITY PACKAGE FOR ULTRASONIC TRANSDUCER ACOUSTIC MODE CONTROL
A micromechanical system (MEMS) device package comprising a substrate and a first enclosure including a first cavity, coupled to the substrate. Wherein a transverse dimension of the first cavity relative to the substrate is configured to reduce undesirable acoustic modes within the first cavity and the first cavity comprises an acoustic port. A MEMS device is located inside the first cavity and an Application Specific Integrated Circuit (ASIC) is communicatively coupled to the MEMS device and located outside the first cavity.
1 . A micromechanical system (MEMS) device package comprising;
a substrate;
a first enclosure including a first cavity, coupled to the substrate and wherein a transverse dimension of the first cavity relative to the substrate is configured to reduce undesirable acoustic modes within the first cavity, where in the first cavity comprises an acoustic port;
a MEMS device located inside the first cavity;
an Application Specific Integrated Circuit (ASIC) communicatively coupled to the MEMS device and located outside the first cavity.
2 . The MEMS device package of claim 1 wherein a cross section of the first cavity has a constant radius with respect to the height to reduce the occurrence of undesirable acoustic modes.
3 . The MEMS device package of claim 1 wherein the first enclosure further includes a second cavity and wherein the ASIC is located inside the second cavity.
4 . The MEMS device package of claim 3 wherein the second cavity has an irregular shape.
5 . The MEMS device package of claim 3 , wherein a shape of the second cavity is substantially a parallelepiped.
6 . The MEMS device package of claim 3 , wherein first and second enclosures have separate metal walls and separate lids.
7 . The MEMS device of claim 3 , wherein first and second enclosures have separate metal walls and common lid.
8 . The MEMS device package of claim 1 wherein the substrate forms a side of the first enclosure and a side of the first cavity.
9 . The MEMS device package of claim 1 wherein the first enclosure includes any combination of metal sides, molded sides, or laminate sides and a metal cap, molded cap, or laminate cap.
10 . The MEMS device package of claim 1 further comprising a second enclosure including at least a second cavity, coupled to the substrate wherein the ASIC is located inside the second cavity
11 . The MEMS device package of claim 10 wherein the second enclosure includes any combination of metal sides, molded sides, or laminate sides and a metal cap, molded cap, or laminate cap.
12 . The MEMS device package of claim 10 wherein the second cavity has an irregular shape.
13 . The MEMS device package of claim 1 wherein the MEMS device is an Ultrasonic Transducer.
14 . The MEMS device package of claim 1 , wherein the MEMS device is disposed over the acoustic port,
15 . The MEMS device package of claim 1 , further comprising an accelerometer or a gyroscope in the second cavity.
16 . The MEMS device package of claim 15 , where in the ASIC is shared with the accelerometer or gyroscope.
17 . The MEMS device package of claim 1 wherein the MEMS device is coupled to the substrate.
18 . The MEMS device package of claim 1 wherein a dimension of the cavity is chosen to reduce reflections of wavelengths corresponding to a characteristic frequency of a mode of oscillation of the MEMS device.
19 . The MEMS device package of claim 1 wherein the first cavity is hemispherical in shape.
20 . The MEMS device package of claim 1 , the first enclosure having a curved inner wall of the cavity and an outer wall, wherein the outer cavity wall is substantially planar.
21 . The MEMS device package of claim 1 , where in the MEMS device is electrically connected to the substrate by wirebonds.
22 . The MEMS device package of claim 1 , where in the second enclosure comprises over molded ASIC.
23 . The MEMS device package of claim 1 wherein the first cavity has an irregular shape.
24 . The MEMS device package of claim 1 , wherein a thickness of the MEMS device package is less than a thickness of the substrate, the enclosure, the MEMS device and the ASIC combined.