JP2016058880A - Microphone device capable of reducing influence of noise coupling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microphone device in which the influence of noise coupling is largely reduced through arrangement of various integration styles between an integrated circuit and a MEMS unit.SOLUTION: A microphone device 200 comprises: a carrier board 210; a MEMS unit 220; an integrated circuit 230; and a top cover 240. The MEMS unit includes: a substrate 223; a cap 224; and a MEMS microphone 250. The cap is attached on the substrate, and made of a conductive material. The MEMS microphone is formed between the cap and the substrate. A combination of the MEMS microphone and the cap forms a resonance cavity. The integrated circuit is attached on the carrier board, and disposed to control an operation of the MEMS microphone. The top cover is connected to the carrier board. The MEMS unit and the integrated circuit are both located in a space 211 formed by the carrier board and the top cover.SELECTED DRAWING: Figure 2

Description

  The present invention relates to microphone devices, and more particularly to integrated microelectromechanical systems (MEMS).

  Microelectromechanical systems (MEMS) integrate various electronic, electrical engineering and mechanical functions into microelements through a semiconductor manufacturing process. Compared to microphones assembled using conventional methods, MEMS microphones have the advantages of smaller size, reduced power consumption, and better resistance to environmental disturbances such as temperature changes, shocks and electromagnetic interference.

  Please refer to FIG. 1 showing a conventional MEMS microphone 100. The conventional MEMS microphone 100 includes a carrier board 20, a silicon substrate 30, a thin film 40, a back plate 50, and an application specific IC (ASIC) 60, and the silicon substrate 30, the thin film 40, the back plate 50, and an application specific IC (ASIC). ) 60 forms a MEMS unit. The thin film 40 is a flexible thin film that vibrates in response to sound pressure, producing a slight change, resulting in a dynamic shift in its position. The capacitance of the MEMS microphone 100 changes accordingly. Both the silicon substrate 30 and the ASIC 60 are configured on the carrier board 20. The ASIC 60 provides a regular bias voltage to amplify the output signal in order to operate the MEMS normally.

  Due to the ASIC 60, there may be noise in the MEMS. This causes serious interference with the MEMS microphone 100 and performance is degraded. Therefore, there is a need to provide a new capacitive microphone to solve the above problems.

  In view of the above, one of the objects of the present invention is to provide a capacitive microphone having a conductive cap and / or a transmission interface arranged to transmit a differential signal, to solve the above problems. It is.

  Embodiments of the present invention provide a microphone device that includes a carrier board, a microelectromechanical system unit, an integrated circuit (IC), and a top cover. The microelectromechanical system unit includes a substrate, a cap, and a capacitive microphone. The cap is mounted on the substrate and constitutes a conductive material. The capacitive microphone is positioned between the cap and the carrier board, and the capacitive microphone and the cap form a resonant cavity. The IC is mounted on the carrier board and arranged to control the capacitive microphone. The top cover is connected to the carrier board, and both the microelectromechanical system unit and the IC are located in the space formed by the carrier board and the top cover.

  Embodiments of the present invention configure a conductive cap and a differential interface to achieve transmission between an IC and a capacitive microphone. This greatly reduces the effects of noise coupling through various integrated arrangements between the IC and the MEMS unit. Therefore, the efficiency of the capacitive microphone is improved.

  These and other objects of the present invention will be apparent to those skilled in the art upon reading the following detailed description of the preferred embodiment shown in the various figures and drawings.

It is a figure which shows the conventional MEMS microphone.

It is a figure which shows the microphone apparatus according to the 1st Embodiment of this invention.

It is a figure which shows the difference structure comprised by the microphone apparatus shown in FIG.

It is a figure which shows the microphone apparatus according to the 2nd Embodiment of this invention.

It is a figure which shows the microphone apparatus according to the 3rd Embodiment of this invention.

It is a figure which shows the microphone apparatus according to the 4th Embodiment of this invention.

  Certain language is used throughout the detailed description and the following claims. As those skilled in the art will appreciate, manufacturers can refer to components by different names. This document does not intend to distinguish between components that differ in name but not function. In the following detailed description and claims, the terms “include” and “comprise” are used in an open-ended fashion and therefore consist of “ It should not be interpreted as a closed-end wording such as “consist of”). Also, the term “couple” is intended to mean an indirect or direct electrical connection. Thus, when one device couples to another device, this connection can be through a direct electrical connection or an indirect electrical connection via another device and connection.

  Please refer to FIG. 2, which shows a microphone device 200 according to the first embodiment of the present invention. The microphone device 200 includes (but is not limited to) a carrier board 210, a MEMS unit 220, an integrated circuit (IC) 230, and a top cover 240. The carrier board 210 may be a printed circuit board (PCB), but is not limited thereto in the present invention. The MEMS unit 220 includes (but is not limited to) a substrate 223, a cap 224, and a MEMS microphone 250, and the substrate 223 may be a silicon substrate. The cap 224 is formed on the substrate 223 and is made of a conductive material. The cap 224 has an opening 246. The cap 224 in this embodiment provides dust / particle protection and an electromagnetic shield for the MEMS microphone 250. The MEMS microphone 250 is formed between the cap 224 and the substrate 223, and the MEMS microphone 250 and the cap 224 form a resonant cavity. IC 230 is formed on carrier board 210 and is arranged to control the operation of MEMS microphone 250. The upper cover 240 is connected to the carrier board 210. The joint between the top cover 240 and the carrier board 210 is airtight, and the MEMS unit 220 and the IC 230 are both in the space 211 formed by the carrier board 210 and the top cover 240. The material of the upper cover 240 may be a conductive material, but the present invention is not limited to this. The material of the top cover 240 may be a PCB material. The top cover 240 has an opening 242, which can be formed so as not to be directly above the opening 246 of the cap 224, as shown in FIG. This design reduces the possibility of dust and other particles falling on the MEMS microphone 250. In other embodiments, the opening 242 in the top cover 240 can be directly above the opening 246 in the cap 224.

  In this embodiment, the substrate 223 of the MEMS unit 220 is configured on the carrier board 210, and the IC 230 is coupled to the MEMS microphone 250 via the differential interface 270. Please refer to FIG. 3, which shows a differential structure 300 formed in the microphone device 200 shown in FIG. The differential interface 270 couples the two capacitors 251 and 252 of the capacitive microphone to the two ends 231 and 232 of the IC 230. Due to this differential configuration, the phase of the noise output by end 231 is opposite to the phase of the noise output by end 232 and therefore cancels each other. Accordingly, interference from the surroundings is greatly reduced, and the efficiency of the microphone device 200 is improved.

  Capacitors 251 and 252 are coupled to differential amplifier 280 in MEMS microphone 250. Differential amplifier 280 receives the differential input and generates a single-ended output. The differential interface 270 shown in FIG. 3 is merely an example of the present invention. Means for realizing transmission between the IC and the capacitive microphone through the differential configuration are within the scope of the present invention.

  Please refer to FIG. 4, which shows a microphone device 400 according to a second embodiment of the present invention. The difference between the first embodiment and the second embodiment is that the IC 430 of the second embodiment is integrated into the substrate 423 of the MEMS unit 420. Based on the integrated structure described above, the IC 430 transmits a signal to the MEMS microphone 250 and thus does not require a transmission interface (eg, the differential interface 270 described above). Therefore, there is no noise in the MEMS microphone 250. Similarly, compared to the prior art, the microphone device 400 greatly reduces noise interference and therefore provides better performance. For the sake of brevity, the remaining elements in the microphone device 400 that are identical to the elements in the microphone device 200 are not described herein.

  Please refer to FIG. 5, which shows a microphone device 500 according to a third embodiment of the present invention. The difference between the first embodiment and the third embodiment is that the MEMS unit 220 of the third embodiment is stacked on the IC 530, so that the IC 530 is configured between the carrier board 210 and the MEMS unit 220. It is to be done. Similarly, the IC 530 and the MEMS unit 220 form an integrated structure. This means that the IC 530 also no longer requires a transmission interface (eg, the differential interface 270 described above) to transmit the signal to the MEMS microphone 250. And no noise exists in the MEMS microphone 250. Compared to the prior art, the microphone device 500 can reduce noise interference and therefore provides better performance. For the sake of brevity, the remaining elements of the microphone device 500 that are identical to the elements of the microphone device 200 are not described herein.

  The present invention does not limit the form of integration between the IC and the capacitive microphone. In some variations of the invention, the integration between the IC and the capacitive microphone may be arranged differently, but has the same effect of reducing noise in the capacitive microphone.

  Please refer to FIG. 6, which shows a microphone device 600 according to a fourth embodiment of the present invention. The difference between the first embodiment and the fourth embodiment is that in the fourth embodiment, the carrier board 610 of the microphone device 600 has an opening 642. The substrate 223 of the MEMS unit 220 is configured on the carrier board 610, and the MEMS microphone 250 exists directly above the opening 642 of the carrier board 610. Further, the top cover 640 does not have an opening. In the configuration of the present embodiment, since the upper cover 640 is sealed, dust and particles do not fall on the MEMS microphone 250. In addition, the transmission interface 270 employs the above-described differential interface, and noise can be further reduced. For the sake of brevity, the remaining elements of the microphone device 600 that are identical to the elements of the microphone device 200 are not described herein.

  In summary, embodiments of the present invention provide transmission between an IC and a capacitive microphone through a differential interface and provide various arrangements that integrate the MEMS unit and the IC. Therefore, the influence of noise coupling is greatly reduced, thereby improving the efficiency of the capacitive microphone.

  Those skilled in the art will readily recognize that many modifications and variations of the apparatus and method can be made in the course of retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only to the metes and bounds of the appended claims.

US Patent Application Publication No. 2012 / 0188727A1 Chinese Patent Application No. 1029327221

Claims (10)

With carrier board;
A substrate,
A cap mounted on the substrate and comprising a conductive material;
A micro-electromechanical system (MEMS) unit having a capacitive microphone positioned between the cap and the carrier board, wherein the capacitive microphone and the cap form a resonant cavity;
An integrated circuit (IC) mounted on the carrier board and arranged to control the capacitive microphone;
An upper cover connected to the carrier board;
Have
The MEMS unit and the integrated circuit are both positioned in a space formed by the carrier board and the top cover.
Microphone device.   The microphone device according to claim 1, wherein the cap has an opening.   The microphone device according to claim 2, wherein the upper cover has an opening, and the opening of the upper cover does not exist directly above the opening of the cap.   The microphone device according to claim 1, wherein the carrier board has an opening, the substrate of the MEMS unit is configured on the carrier board, and the capacitive microphone is directly above the opening of the carrier board. .   The microphone device according to claim 1, wherein the substrate of the MEMS unit is configured on the carrier board, and the IC is coupled to the capacitive microphone through a differential interface.   The microphone device according to claim 1, wherein the IC is formed in the substrate of the MEMS unit.   The microphone device according to claim 1, wherein the MEMS unit is stacked on the IC.   The microphone device according to claim 1, wherein the upper cover is made of a conductive material.   The microphone device according to claim 1, wherein the carrier board is a printed circuit board (PCB).   The microphone device according to claim 1, wherein a joint between the upper cover and the carrier board is airtight.

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