US 11,938,515 B2
Method for tuning the resonant frequency of a piezoelectric micromachined ultrasonic transducer
Fabian Goericke, Berkeley, CA (US); Stefon Shelton, Berkeley, CA (US); and Benedict Costello, Berkeley, CA (US)
Assigned to InvenSense, Inc., San Jose, CA (US)
Appl. No. 16/957,064
Filed by InvenSense, Inc., San Jose, CA (US)
PCT Filed Dec. 21, 2018, PCT No. PCT/US2018/067260
§ 371(c)(1), (2) Date Jun. 22, 2020,
PCT Pub. No. WO2019/126729, PCT Pub. Date Jun. 27, 2019.
Claims priority of provisional application 62/609,987, filed on Dec. 22, 2017.
Prior Publication US 2020/0338592 A1, Oct. 29, 2020
Int. Cl. B06B 1/06 (2006.01); H10N 30/04 (2023.01)
CPC B06B 1/0629 (2013.01) [B06B 1/0651 (2013.01); B06B 1/0666 (2013.01); B06B 1/0685 (2013.01); H10N 30/04 (2023.02); Y10T 29/42 (2015.01)] 11 Claims
OG exemplary drawing
 
1. A method comprising:
establishing an acceptable range of resonant frequencies (Δf0) for a plurality of piezoelectric micromachined ultrasonic transducer (PMUTs) (500);
providing the plurality of PMUTs such that each PMUT of the plurality thereof includes a membrane (204) that is characterized by a first design that includes a first lateral dimension (D1), a center (C1), and a periphery (P1), wherein each PMUT of the plurality thereof has a resonant frequency that is based on at least one of the stiffness and mass of its respective membrane;
determining a preliminary value (fn-1,1 through fn-M,N) for the resonant frequency of each PMUT of the plurality thereof;
determining a first desired resonant-frequency change for a first PMUT (502-1,1) of the plurality thereof, wherein the first desired resonant-frequency change is based on the acceptable range of resonant frequencies, the preliminary value (fn-1,1) for the first PMUT, and at least one other preliminary value of the plurality thereof; and
imparting the first desired resonant-frequency change on the first PMUT by establishing a first profile of at least one of stiffness and mass along the first lateral dimension of the first membrane (204-1,1).