CN210781338U

CN210781338U - MEMS microphone protection circuit based on thermistor

Info

Publication number: CN210781338U
Application number: CN201921798381.7U
Authority: CN
Inventors: 杨国庆
Original assignee: Chaoyang Jushengtai Xinfeng Technology Co Ltd
Current assignee: Chaoyang Jushengtai Xinfeng Technology Co Ltd
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2020-06-16
Anticipated expiration: 2029-10-24

Abstract

The utility model relates to a microphone field especially relates to a MEMS microphone protection circuit based on thermistor, contains packaging substrate, packaging substrate is last to be fixed with first resistance, second resistance, third resistance and sensitive resistance respectively, be fixed with the Sensor chip directly over the sensitive resistance, the Sensor chip is connected with the ASIC chip through the bonding wire, the ASIC chip links to each other with packaging substrate electrical property through the bonding wire, packaging substrate top still is fixed with the shell, there are BIAS end and VOUT end on the Sensor chip, BIAS end links to each other with the BIAS end electrical property of ASIC chip on the Sensor chip, VOUT end links to each other with the VOUT end electrical property of ASIC chip on the Sensor chip, first resistance one end links to each other with second resistance one end and power positive pole, the first resistance other end links to each other with sensitive resistance one end and relay one end. The device can effectively ensure that the circuit of the MEMS microphone is disconnected when the environment changes, and protect the MEMS microphone.

Description

MEMS microphone protection circuit based on thermistor

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of microphones, in particular to an MEMS microphone protection circuit based on a thermistor.

[ background of the invention ]

MEMS is a Micro-Electro mechanical System (Micro-Electro mechanical System), which refers to a sensor device with a size of several millimeters or less, and the internal structure of the sensor device is generally in the micrometer or nanometer level, and the sensor device is an independent intelligent System. Briefly, the MEMS is a silicon-based sensor formed by miniaturizing mechanical components of a conventional sensor, fixing a device on a silicon wafer (wafer) by a three-dimensional stacking technique, for example, a three-dimensional through-silicon via (TSV) technique, and finally cutting and assembling the device in a specially-customized packaging form according to different application occasions. The MEMS has the advantages of miniaturization and high integration degree which cannot be achieved by the common sensor;

the Sensor chip of the MEMS microphone belongs to a sensitive component and is easily influenced by external force, and because the distance between two polar plates is extremely small, generally about 2 mu m, the working state of the Sensor can be influenced by the external environment, and meanwhile, the risk of polar plate short circuit also exists, so that the microphone can be greatly damaged. The microphone can work in certain high and low temperature environments, but beyond the temperature range, the microphone still can be in a working state, and the working state can cause damage to the MEMS microphone.

The invention is developed and proposed aiming at the defects of the prior art.

[ summary of the invention ]

The invention aims to overcome the defects of the prior art and provides an MEMS microphone protection circuit based on a thermistor, which can cut off a power supply when the working state of a microphone is affected or even fails due to the change of an external environment, plays a role in protecting a Sensor and is beneficial to prolonging the service life of the microphone.

The invention can be realized by the following technical scheme:

the invention discloses an MEMS microphone protection circuit based on a thermistor, which comprises a packaging substrate, wherein a first resistor, a second resistor, a third resistor and a sensitive resistor are respectively fixed on the packaging substrate, a Sensor chip is fixed right above the sensitive resistor, the Sensor chip is connected with an ASIC chip through a bonding wire, the ASIC chip is electrically connected with the packaging substrate through the bonding wire, a shell is also fixed above the packaging substrate, a BIAS end and a VOUT end are arranged on the Sensor chip, the BIAS end on the Sensor chip is electrically connected with the BIAS end of the ASIC chip, the VOUT end on the Sensor chip is electrically connected with the VOUT end of the ASIC chip, one end of the first resistor is connected with one end of the second resistor and a positive electrode of a power supply, the other end of the first resistor is connected with one end of the sensitive resistor and one end of a relay, the other end of the second resistor is connected with one end of the third resistor and the other end of the relay, the other end of the sensitive resistor is connected with the other end of the third resistor and the negative electrode of the power supply, the relay is further connected with the power supply end of the ASIC chip, the OUT end on the ASIC chip is electrically connected with the packaging substrate through a capacitor, the ASIC chip is further internally provided with a charge pump, and the sensitive resistor is a thermistor. The thermistor is a positive temperature coefficient thermistor, the lower the temperature at the two ends of the positive temperature coefficient thermistor is, the smaller the resistance value of the resistor is, the smaller the voltage on a voltage relay connected with the thermistor in parallel is, when the temperature is too low, the voltage on the voltage relay is smaller than the threshold value set by the chip in the relay, the relay is disconnected, and an external power supply stops supplying power to the MEMS microphone, so that the purpose of protecting the circuit at low temperature is achieved, and the service life of the MEMS microphone can be effectively prolonged. The MEMS microphone has the working principle that the ASIC chip is powered by an external power supply to enable the ASIC chip to enter a working state, the ASIC chip provides bias voltage for the vibrating diaphragm and the back electrode through a charge pump in the ASIC chip to enable potential difference to exist between the vibrating diaphragm and the back electrode of the Sensor chip, so that under the action of external sound pressure, a sound signal is converted into mechanical energy of the vibrating diaphragm, and meanwhile, the Sensor chip outputs an electric signal from a VOUT end of the Sensor chip under the condition that the distance between the vibrating diaphragm and the back electrode is changed by analogy of the working principle of a parallel plate capacitor, the signal is an initial signal of detected sound, and the signal is processed by the signal ASIC chip and then is output from an OUT end; ASIC chip's supply terminal links to each other with the relay, the relay is voltage relay, the inside chip of relay can pass through the voltage control break-make, and simultaneously, the input of relay is controlled by a bridge circuit, bridge circuit contains the resistance and a sensitive resistor of three fixed resistance, when the sensitive resistor resistance reduces, when voltage is less than the threshold value of setting for in the relay on the relay, the relay disconnection, external power stops to supply power for the vibrating diaphragm and the back of the body utmost point of Sensor chip on the MEMS microphone, can effectively avoid vibrating diaphragm and the back of the body utmost point short circuit neutralization charge of Sensor chip, can cause Sensor chip electric capacity breakdown even, thereby lead to MEMS microphone inefficacy.

Preferably, the casing is provided with a sound inlet hole.

Preferably, the bonding wire is made of metal materials such as gold, aluminum, copper and the like.

Compared with the prior art, the invention has the following advantages:

the MEMS microphone is powered after the sensitive resistor and the relay are connected in parallel, when the resistance value of the sensitive resistor is reduced, the relay is disconnected, and the power supply stops supplying power to the MEMS microphone, so that the effect of protecting a circuit can be effectively achieved, and the service life of the MEMS microphone is effectively prolonged.

[ description of the drawings ]

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings, in which:

FIG. 1 is an exploded view of the present invention;

FIG. 2 is a schematic structural view of the present invention;

FIG. 3 is a circuit diagram of the present invention;

FIG. 4 is a diagram of a Sensor chip structure according to the present invention;

FIG. 5 is a diagram of the working state of the Sensor chip;

in the figure: 1. a housing; 2. a bonding wire; 3. an ASIC chip; 4. a Sensor chip; 401. A back electrode; 403. vibrating diaphragm; 402. silicon-based; 5. a sensitive resistor; 6. a first resistor; 7. a second resistor; 8. a third resistor; 9. a package substrate; 10. a relay; 11. a sound inlet hole;

[ detailed description ] embodiments

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings:

as shown in fig. 1 to 5, the present invention discloses a thermistor-based MEMS microphone protection circuit, which comprises a package substrate 9, wherein a first resistor 6, a second resistor 7, a third resistor 8 and a sensitive resistor 5 are respectively fixed on the package substrate 9, a Sensor chip 4 is fixed right above the sensitive resistor 5, the Sensor chip 4 is connected with an ASIC chip 3 through a bonding wire 2, the ASIC chip 3 is electrically connected with the package substrate 9 through the bonding wire 2, a housing 1 is further fixed above the package substrate 9, the Sensor chip 4 is provided with a BIAS terminal and a VOUT terminal, the BIAS terminal of the Sensor chip 4 is electrically connected with the BIAS terminal of the ASIC chip 3, the VOUT terminal of the Sensor chip 4 is electrically connected with the VOUT terminal of the ASIC chip 3, one end of the first resistor 6 is connected with one end of the second resistor 7 and an anode of a power supply, the other end of the first resistor 6 is connected with one end of the sensitive resistor 5 and one end of a relay 10, the other end of the second resistor 7 is connected with one end of the third resistor 8 and the other end of the relay 10, the other end of the sensitive resistor 5 is connected with the other end of the third resistor 8 and the negative electrode of the power supply, the relay 10 is also connected with the power supply end of the ASIC chip 3, the OUT end on the ASIC chip 3 is electrically connected with the packaging substrate 9 through a capacitor, and the ASIC chip 3 is also internally provided with a charge pump. The working principle of the MEMS microphone is that an external power supply supplies power to an ASIC chip 3 to enable the ASIC chip 3 to enter a working state, the ASIC chip 3 provides bias voltage for a vibrating diaphragm 403 and a back electrode 401 on a Sensor chip 4 through a charge pump in the ASIC chip 3 to enable potential difference to exist between the vibrating diaphragm 403 and the back electrode 401 of the Sensor chip 4, so that under the action of external sound pressure, a sound signal is converted into mechanical energy of the vibrating diaphragm 403, and meanwhile, compared with the working principle of a parallel plate capacitor, under the condition that the distance between the vibrating diaphragm 403 and the back electrode 401 is changed, the Sensor chip 4 has an electric signal output from a VOUT end of the Sensor chip 4, the signal is an initial signal of detected sound, and the signal is processed by the signal ASIC chip 3 and then output from an OUT end; the power supply end of ASIC chip 3 links to each other with relay 10, relay 10 is voltage relay 10, the inside chip of relay 10 can be through voltage control break-make, and simultaneously, the input of relay 10 is controlled by a bridge circuit, bridge circuit contains the resistance of three fixed resistance and a sensitive resistance 5, when the resistance of sensitive resistance 5 reduces, when voltage is less than the threshold value of setting in the relay 10 on the relay 10, relay 10 disconnection, external power stops to supply power for vibrating diaphragm 403 and back electrode 401 of Sensor chip 4 on the MEMS microphone, can effectively avoid vibrating diaphragm 403 and the back electrode 401 of Sensor chip 4 short circuit neutralization charge, can cause the breakdown of Sensor chip 4 electric capacity even, thereby lead to MEMS microphone inefficacy.

As shown in fig. 4, the structure of the Sensor chip 4 is shown, the Sensor chip 4 is composed of a diaphragm 403, a back electrode 401 and a silicon substrate 402, the diaphragm 403 and the back electrode 401 are fixed inside a cavity of the silicon substrate 402 by a semiconductor processing technology (etching, polishing, evaporation, etc.), the operation principle of the chip is equivalent to a parallel plate capacitor, the diaphragm 403 and the back electrode 401 constitute upper and lower substrates of the capacitor, charges directionally move under the action of voltage, a stable voltage difference is formed between the upper and lower substrates, when external sound pressure acts on the diaphragm 403, the distance between the diaphragm 403 and the back electrode 401 changes, the formula C ∈ S/4 π kd shows that the capacitance of the capacitor changes accordingly when the distance changes (C: capacitance ∈: dielectric constant, S: the facing area d between the diaphragm 403 and the back electrode 401: the distance between the two plates, k: Q/C), when the distance changes, the output voltage value changes (Q: the constant charge value of the capacitor 403, Q: the constant voltage, U-k: q.s — C, when the voltage of the chip deforms, the chip is 1, the voltage of the chip after the chip is mechanically deformed, the chip is transformed into U-3632, the voltage of the chip, and the chip outputs U — 1-3632U-U voltage after the sound pressure of the chip is changed under the action of the external sound pressure.

Wherein, the shell 1 is provided with a sound inlet hole 11.

Wherein, the bonding wire 2 is made of copper metal.

Wherein the sensitive resistor 5 is a thermistor. The thermistor is a positive temperature coefficient thermistor, the lower the temperature at the two ends of the positive temperature coefficient thermistor is, the smaller the resistance value of the resistor is, the smaller the voltage on the voltage relay 10 connected with the thermistor in parallel is, when the temperature is too low, the voltage on the voltage relay 10 is smaller than the threshold value set by the chip in the relay 10, the relay 10 is disconnected, and an external power supply stops supplying power to the MEMS microphone, so that the purpose of protecting the circuit at low temperature is achieved, and the service life of the MEMS microphone can be effectively prolonged.

The above description is only a preferred embodiment of the present invention, and it should be noted that a person skilled in the art can make various changes, modifications, substitutions and alterations to the embodiments without departing from the technical principles of the present invention, and such changes, modifications, substitutions and alterations should also be regarded as the protection scope of the present invention.

Claims

1. A kind of MEMS microphone protective circuit based on thermistor, characterized by that: comprises a packaging substrate, a first resistor, a second resistor, a third resistor and a sensitive resistor are respectively fixed on the packaging substrate, a Sensor chip is fixed right above the sensitive resistor, the Sensor chip is connected with an ASIC chip through a bonding wire, the ASIC chip is electrically connected with the packaging substrate through the bonding wire, a shell is further fixed above the packaging substrate, a BIAS end and a VOUT end are arranged on the Sensor chip, the BIAS end on the Sensor chip is electrically connected with the BIAS end of the ASIC chip, the VOUT end on the Sensor chip is electrically connected with the VOUT end of the ASIC chip, one end of the first resistor is connected with one end of the second resistor and the positive pole of a power supply, the other end of the first resistor is connected with one end of the sensitive resistor and one end of a relay, the other end of the second resistor is connected with one end of the third resistor and the other end of the relay, the other end of the sensitive resistor is connected with the other end of the third resistor and the negative pole of the power supply, the relay is further connected with a power supply end of the ASIC chip, an OUT end on the ASIC chip is electrically connected with the packaging substrate through a capacitor, and the sensitive resistor is a thermistor.

2. A thermistor-based MEMS microphone protection circuit according to claim 1, characterized in that: and the shell is provided with a sound inlet hole.