CN110856090A - Novel anti-radio frequency interference micro-electro-mechanical system microphone structure - Google Patents

Abstract

The embodiment of the invention discloses a novel anti-radio frequency interference micro-electro-mechanical system microphone structure, which comprises a PCB substrate, an MEMS chip, a radio frequency filter, an ASIC chip, a shell, an MEMS chip and a power supply, wherein the MEMS chip is packaged on the top surface of the PCB substrate, the bottom of the radio frequency filter is arranged on the top surface of the PCB substrate through a bonding pad and is positioned at one side of the MEMS chip, the ASIC chip is arranged on the top surface of the radio frequency filter, the input end of the ASIC chip is connected with the output end of the MEMS chip, the shell covers the outer sides of the MEMS chip, the radio frequency, the radio frequency filter and the ASIC chip are reasonably distributed, the area and the space on the PCB substrate are utilized to the maximum extent, the occupied space is saved, the structure is simple, the radio frequency filter can easily achieve the filtering effect, the traditional gold wire connection is omitted, the circuit board layout is clear and concise, the manufacturing process is simplified, the subsequent overhaul and updating are convenient, and the cost is reduced.

Description

A Novel Micro-Electro-Mechanical System Microphone Structure Against Radio Frequency Interference

technical field

The invention relates to the field of electronic devices, in particular to a novel micro-electromechanical system microphone structure with anti-radio frequency interference.

Background technique

The MEMS microphone is translated as a sound sensor, and the sound sensor acts as a microphone (microphone). It is used to receive sound waves and display the vibration image of the sound, but it cannot measure the intensity of the noise. The sensor incorporates a sound-sensitive condenser electret microphone. The sound waves vibrate the electret film inside the microphone, causing a change in capacitance and a tiny voltage corresponding to the change. This voltage is then converted into a voltage of 0-5V, accepted by the data collector through A/D conversion, and transmitted to the computer.

One drawback of MEMS microphones is RF (RF Radio Frequency) interference. The sources of radio frequency interference are: mobile phones, walkie-talkies, etc.; if it is in a special place, such as hospital X-ray machines, gamma knives, CT machines and other equipment will bring strong RF interference.

To prevent this proximity effect, system designers must place the microphone away from the device antenna and isolate its power supply to mitigate RF interference. This often sacrifices the design aesthetics of the product.

In order to combat radio frequency interference, traditional MEMS microphones generally use the method of burying resistors and capacitors on the PCB substrate to realize RF filtering. The embedded resistors and capacitors are limited, and the manufacturing cost is high and the manufacturing is complicated.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a novel MEMS microphone structure with resistance to radio frequency interference to solve the above technical problems.

The technical problem solved by the present invention can be realized by the following technical solutions:

A new type of micro-electromechanical system microphone structure resistant to radio frequency interference, including

a PCB substrate;

a MEMS chip, packaged on the top surface of the PCB substrate;

a radio frequency filter, the bottom of the radio frequency filter is provided with a pad, the radio frequency filter is arranged on the top surface of the PCB substrate through the pad, and is located on one side of the MEMS chip;

an ASIC chip, disposed on the top surface of the radio frequency filter, the input end of the ASIC chip is connected to the output end of the MEMS chip;

A casing is fixed on the top surface of the PCB substrate and covers the outside of the MEMS chip, the radio frequency filter and the ASIC chip.

Preferably, the PCB substrate is a double-layer circuit board, and the bottom of the PCB substrate is provided with pads.

Preferably, the MEMS chip includes a silicon diaphragm and a silicon back electrode, the silicon diaphragm is parallel to the silicon back electrode, and the silicon diaphragm and the silicon back electrode form a parallel plate capacitor.

Preferably, a sound transmission cavity is set between the silicon diaphragm and the PCB substrate.

Preferably, the bottom end of the MEME chip is hermetically packaged on the top surface of the PCB substrate.

Preferably, the radio frequency filter is packaged on the top surface of the PCB substrate using CSP packaging technology, and the bottom end of the radio frequency filter is connected to the circuit on the top surface of the PCB substrate through a pad.

Preferably, the shell is made of metal material.

Preferably, a sound hole is provided on the PCB substrate or the housing.

Beneficial effects: The MEMS chip, the radio frequency filter and the ASIC chip on the MEMS microphone of the present invention are reasonably distributed, the surface base and space on the PCB substrate are maximized, the occupied space is saved, the structure is simple, and the radio frequency filter can easily achieve The filtering effect eliminates the traditional gold wire connection, and the circuit board layout is clear and concise, which simplifies the manufacturing process, facilitates subsequent maintenance and update, and reduces costs.

Description of drawings

FIG. 1 is a schematic cross-sectional view of the structure of the MEMS microphone of the present invention.

In the figure: 1-PCB substrate; 2-MEMS chip; 3-RF filter; 4-ASIC chip; 5-Acoustic hole; 6-Pad; 7-First signal line; 8-Second signal line;

21-silicon diaphragm; 22-silicon back pole; 23-sound transmission cavity.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention.

As shown in FIG. 1 , the present invention provides a new type of MEMS microphone structure with anti-radio frequency interference, comprising:

A PCB substrate 1, a sound hole 5 is arranged on the PCB substrate 1, and the sound hole 5 is used to transmit sound; the sound hole 5 can also be arranged on the shell 9 to transmit the sound to the outside of the earphone.

A MEMS chip 2, packaged on the top surface of the PCB substrate 1, located at the top of the sound hole, the MEMS chip is used for receiving sound and generating corresponding audio signals according to sound vibration;

A radio frequency filter 3, the bottom of the radio frequency filter 3 is provided with a pad, the radio frequency filter 3 is arranged on the top surface of the PCB substrate through the pad 6, packaged on the top surface of the PCB substrate 1, and is located on a side of the MEMS chip 2. On the side, the radio frequency filter 3 is connected to the output end of the electrical signal to filter the radio frequency signal to make the output sound quality more pure;

An ASIC chip 4 is packaged on the top surface of the radio frequency filter 3, the input end of the ASIC chip 4 is connected to the output end of the MEMS chip 2, and the output end of the ASIC chip 4 is connected to the circuit of the PCB substrate 1; the ASIC chip is used for special applications Integrated circuit (ASIC, Application Specific Integrated Circuit) chip technology, its function is to convert and amplify the high-resistance audio electrical signal transmitted from the MEMS chip 2 into a low-resistance electrical signal, and then transmit it to the radio frequency filter. The circuit filters and outputs an electrical signal matching the front-end circuit to complete the acoustic-electrical conversion. Sound recognition is achieved by reading electrical signals. In the case of the first shell 9, the front section of the shell 9 is in the shape of an inverted "凵". It is fixed on the top surface of the PCB substrate and covers the outside of the MEMS chip 2, the radio frequency filter 3 and the ASIC chip 4. The casing 9 is used as a protection device for the MEMS microphone, which plays a certain role in sealing, moisture-proof and external force protection. Extend the service life of the internal structure of the MEMS microphone.

The advantages of the invention are that the MEMS chips, radio frequency filters and ASIC chips on the PCB substrate are reasonably distributed, the surface base and space on the PCB substrate are maximized, the occupied space is saved, the structure is simple, and the radio frequency filter can easily achieve the filtering effect , the traditional gold wire connection is discarded, the layout of the circuit board is clear and concise, the manufacturing process is simplified, and the subsequent maintenance and update are convenient, and the cost is reduced.

As a preferred embodiment of the present invention, the PCB substrate 1 is a double-layer circuit board. Double-sided is an extension of single-sided. When single-layer wiring cannot meet the needs of electronic products, double-sided is used. Both sides have copper cladding and traces, and the lines between the two layers can be conducted through vias to form the required network connections. The double-layer PCB design makes the circuit arrangement more compact and saves space. The bottom of the PCB substrate 1 is provided with pads, which are welded to the inside of the casing through the pads.

As a preferred embodiment of the present invention, the MEMS chip 2 includes a silicon diaphragm 21 and a silicon back electrode 22, the silicon diaphragm 21 is parallel to the silicon back electrode 22, and the silicon diaphragm 21 and the silicon back electrode 22 form a parallel plate capacitors. A power line is connected to the silicon back electrode 22 and the silicon diaphragm 21 respectively, so that a certain voltage is generated between the silicon back electrode 22 and the silicon diaphragm 21 . When the silicon diaphragm 21 moves, the distance between the silicon diaphragm 21 and the silicon back electrode 22 changes, and the capacitance changes, thereby converting the sound pressure signal into an electrical signal.

As a preferred embodiment of the present invention, a sound transmission cavity 23 is provided between the silicon diaphragm 21 and the PCB substrate 1 , and the sound hole 5 communicates with the sound transmission cavity 23 . The silicon diaphragm 21 is located on the top surface of the sound transmission cavity 23 , that is, after the sound enters the sound transmission cavity 23 from the sound hole 5 , the sound can immediately vibrate the silicon diaphragm 21 to generate a changing electrical signal.

The working process of the MEMS microphone of the present invention is as follows:

The external sound enters the sound transmission cavity 23 from the sound hole 5, and the silicon diaphragm 21 is vibrated under the action of sound pressure, and the distance between the silicon diaphragm 21 and the silicon back pole 22 changes, thereby changing the capacitance value, thereby converting the sound signal. converted into electrical signals. The electrical signal is transmitted to the ASIC chip 4 to convert and amplify the incoming audio electrical signal into a low-resistance electrical signal, and then transmit it to the RF filter 3, which is filtered by the RF anti-noise circuit to output an electrical signal that matches the pre-circuit. Acoustic-electrical conversion is completed.

As a preferred embodiment of the present invention, the overall front cross-section of the MEME chip 2 is in the shape of an inverted "凵", and the bottom end of the MEME chip 2 is sealed and encapsulated on the top surface of the PCB substrate 1. The advantage of the sealed encapsulation is to avoid sound leakage to the In other places, the sensitivity of the silicon diaphragm 21 is higher, so as to avoid the occurrence of noise. Dust can also be prevented from entering the MEMS chip 2 and the radio frequency filter 3 .

As a preferred embodiment of the present invention, the radio frequency filter 3 is packaged on the top surface of the PCB substrate 1 using CSP packaging technology, the packaging is more precise, and the space of the circuit board and the entire MEMS microphone is saved. The bottom end of the RF filter 3 is connected to the circuit on the top surface of the PCB substrate 1 through the pad 6. The pad 6 ensures the electrical connection between the RF filter 3 and the circuit on the PCB substrate 1, so as to ensure that the electrical signal enters the RF filter 3 and passes through. output after filtering.

As a preferred embodiment of the present invention, the output end of the MEMS chip 2 is connected to the input end of the ASIC chip 4 through a first signal line 7 . The first signal line 7 is used to transmit the electrical signal output by the MEMS to the ASIC chip 4 to facilitate subsequent processing of the electrical signal by the ASIC chip 4 .

As a preferred embodiment of the present invention, the output end of the ASIC chip 4 is connected to the circuit of the PCB substrate 1 through a second signal line 8 . The second signal line 8 is used to transmit the signal processed by the ASIC chip 4 to the circuit of the PCB substrate 1. The signal of the PCB substrate 1 is converted by the radio frequency filter 3 to remove the interference signal in the signal, and finally outputs a pure and identifiable signal. signal of.

As a preferred embodiment of the present invention, the casing 9 is made of metal material, which has stronger protection ability and good pressure resistance ability.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the embodiments and protection scope of the present invention. For those skilled in the art, they should be able to realize that all equivalents made by using the description and illustrations of the present invention The solutions obtained by substitutions and obvious changes shall all be included in the protection scope of the present invention.

Claims (8)

1. a novel anti-radio frequency interference MEMS microphone structure, is characterized in that, comprises a PCB substrate; a MEMS chip, packaged on the top surface of the PCB substrate; a radio frequency filter, the bottom of the radio frequency filter is provided with a pad, the radio frequency filter is arranged on the top surface of the PCB substrate through the pad, and is located on one side of the MEMS chip; an ASIC chip, disposed on the top surface of the radio frequency filter, the input end of the ASIC chip is connected to the output end of the MEMS chip; A casing is fixed on the top surface of the PCB substrate and covers the outside of the MEMS chip, the radio frequency filter and the ASIC chip. 2 . The novel MEMS microphone structure with anti-radio frequency interference according to claim 1 , wherein the PCB substrate is a double-layer circuit board and the bottom of the PCB substrate is provided with pads. 3 . 3. A novel MEMS microphone structure with anti-radio frequency interference according to claim 1, wherein the MEMS chip comprises a silicon diaphragm and a silicon back electrode, and the silicon diaphragm and the The silicon back electrodes are parallel, and the silicon diaphragm and the silicon back electrodes form a parallel plate capacitor. 4 . The novel MEMS microphone structure with resistance to radio frequency interference according to claim 3 , wherein a sound transmission cavity is set between the silicon diaphragm and the PCB substrate. 5 . 5 . The novel MEMS microphone structure with resistance to radio frequency interference according to claim 1 , wherein the bottom end of the MEME chip is sealed and packaged on the top surface of the PCB substrate. 6 . 6. A novel MEMS microphone structure with anti-radio frequency interference according to claim 1, wherein the radio frequency filter adopts CSP packaging technology to be packaged on the top surface of the PCB substrate, and the radio frequency filter The bottom end of the device is connected to the circuit on the top surface of the PCB substrate through the pad. 7 . The novel MEMS microphone structure with resistance to radio frequency interference according to claim 1 , wherein the housing is made of metal material. 8 . 8 . The novel MEMS microphone structure with resistance to radio frequency interference according to claim 1 , wherein an acoustic hole is provided on the PCB substrate or the housing. 9 .

Images