CN210694365U - Test circuit and equipment of MEMS microphone - Google Patents
Test circuit and equipment of MEMS microphone Download PDFInfo
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- CN210694365U CN210694365U CN201922311643.9U CN201922311643U CN210694365U CN 210694365 U CN210694365 U CN 210694365U CN 201922311643 U CN201922311643 U CN 201922311643U CN 210694365 U CN210694365 U CN 210694365U
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Abstract
The embodiment of the utility model provides a test circuit and equipment of MEMS microphone, the test circuit of this MEMS microphone includes logic controller, amplifier circuit and A/D converter; the input end of the amplifying circuit is electrically connected with the output end of the MEMS microphone, and the output end of the amplifying circuit is electrically connected with the input end of the analog/digital converter; the amplifying circuit amplifies the electric signal output by the MEMS microphone and outputs the amplified signal to the analog/digital converter; the enabling end of the analog-to-digital converter is electrically connected with the enabling signal output end of the logic controller, and the output end of the analog-to-digital converter is electrically connected with the input end of the logic controller; the analog/digital converter receives an enable signal output by the logic controller, converts the amplified signal into a digital signal and outputs the digital signal to the logic controller; the logic controller receives the digital signal and outputs a sensitivity detection result. The embodiment of the utility model provides a test circuit simple structure of MEMS microphone to can reduce microphone test cost.
Description
Technical Field
The utility model relates to the technical field of circuits, especially, relate to a test circuit and equipment of MEMS microphone.
Background
A microphone is a transducer that converts sound into an electrical signal. Among them, a Micro-Electro-Mechanical System (MEMS) microphone is a microphone manufactured based on MEMS technology. The MEMS microphone has the working principle that the acoustic diaphragm of the capacitor microphone is deformed due to sound pressure interference by utilizing the pressure gradient generated by sound change, so that the capacitance value between the acoustic diaphragm and the silicon back plate is changed. The MEMS microphone has the advantages of good weather resistance, small size and easy digitization, and has great application prospect in electronic equipment such as mobile phones, hearing aids and the like.
Because the MEMS microphone is made of semiconductor materials, the characteristics of the MEMS microphone are stable, and the MEMS microphone cannot be changed due to the influence of the temperature and the humidity of the environment, so that the stable tone quality can be maintained. When the MEMS microphone is applied to a high precision device, the sensitivity of the MEMS microphone is required to meet a corresponding requirement, for example, ± 1 dB. Therefore, when MEMS is applied to a high-precision device, it is necessary to test the sensitivity of MEMS. In the prior art, a special frequency response detection device is usually used for detecting the sensitivity of the MEMS, but the test cost is high, so that the MEMS microphone has high test cost, the test flow is complex, and the test cost is high.
SUMMERY OF THE UTILITY MODEL
An embodiment of the utility model provides a test circuit and equipment of MEMS microphone to it is complicated to solve MEMS microphone check out test set structure among the prior art, and the cost is higher, leads to the test cost high, technical problem that efficiency of software testing is low.
In a first aspect, an embodiment of the present invention provides a test circuit for a MEMS microphone, including: a logic controller, an amplifying circuit and an analog/digital converter;
the input end of the amplifying circuit is electrically connected with the output end of the MEMS microphone, and the output end of the amplifying circuit is electrically connected with the input end of the analog-to-digital converter; the amplifying circuit amplifies the electric signal output by the MEMS microphone and outputs the amplified signal to the analog/digital converter;
the enable end of the analog-to-digital converter is electrically connected with the enable signal output end of the logic controller, and the output end of the analog-to-digital converter is electrically connected with the input end of the logic controller; the analog-to-digital converter receives an enable signal output by the logic controller, converts the amplified signal into a digital signal and outputs the digital signal to the logic controller;
and the logic controller receives the digital signal and outputs a sensitivity detection result.
Optionally, the amplifying circuit includes a first-stage amplifying circuit, a second-stage amplifying circuit, and a third-stage amplifying circuit; the first-stage amplifying circuit, the second-stage amplifying circuit and the third-stage amplifying circuit are sequentially connected;
the input end of the first-stage amplifying circuit is electrically connected with the output end of the MEMS microphone; and the output end of the third-stage amplifying circuit is electrically connected with the input end of the analog-to-digital converter.
Optionally, a first test point is arranged between the first-stage amplification circuit and the second-stage amplification circuit, and a second test point is arranged between the second-stage amplification circuit and the third-stage amplification circuit;
the detector collects signals of the first test point and the second test point and detects the amplified signals of the first-stage amplifying circuit and the second-stage amplifying circuit.
Optionally, the first stage amplifying circuit includes: the circuit comprises a first operational amplifier, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor;
the first end of the first capacitor is electrically connected with the output end of the MEMS microphone, and the second end of the first capacitor is electrically connected with the non-inverting input end of the first operational amplifier through the first resistor;
a first end of the second resistor is electrically connected with a first reference power supply, and a second end of the second resistor is electrically connected with a non-inverting input end of the first operational amplifier through the first resistor;
the inverting input end of the first operational amplifier is grounded through the third resistor and the second capacitor which are sequentially connected in series, and is electrically connected with the output end of the first operational amplifier through the fourth resistor; the output end of the first operational amplifier is electrically connected with the second-stage amplifying circuit; and the reference signal end of the first operational amplifier is electrically connected with a second reference power supply.
Optionally, the third resistor and the fourth resistor are both adjustable resistors.
Optionally, the second stage amplifying circuit includes: the second operational amplifier, the third capacitor, the fifth resistor and the sixth resistor;
the first end of the third capacitor is electrically connected with the output end of the first-stage amplifying circuit; a second end of the third capacitor is electrically connected with an inverting input end of the second operational amplifier through the fifth resistor; the inverting input end of the second operational amplifier is also electrically connected with the output end of the second operational amplifier through the fifth resistor;
the non-inverting input end of the second operational amplifier is electrically connected with the output end of the first-stage amplifying circuit through the sixth resistor; the output end of the second operational amplifier is electrically connected with the input end of the third-stage amplifying circuit; and the reference signal end of the second operational amplifier is electrically connected with a second reference power supply.
Optionally, the third stage of amplifying circuit includes: the third operational amplifier, the fourth capacitor, the seventh resistor and the eighth resistor;
a first end of the fourth capacitor is electrically connected with an output end of the second-stage amplifying circuit, and a second end of the fourth capacitor is electrically connected with an inverting input end of the third operational amplifier through the seventh resistor; the inverting input end of the third operational amplifier is also electrically connected with the output end of the third operational amplifier through the seventh resistor;
the non-inverting input end of the third operational amplifier is electrically connected with the input end of the second-stage amplifying circuit through the eighth resistor; the output end of the third operational amplifier is electrically connected with the input end of the analog-to-digital converter; and the reference signal end of the third operational amplifier is electrically connected with a second reference power supply.
Optionally, the test circuit of the MEMS microphone further includes: a display;
and the display receives the sensitivity detection result output by the logic controller and displays the sensitivity detection result.
Optionally, the logic controller is a programmable logic controller.
In a second aspect, the embodiment of the present invention further provides a test apparatus for a MEMS microphone, including: a sound generating device and a test circuit of the MEMS microphone;
wherein the sound generating device provides an audio signal for the MEMS microphone; the MEMS receives the audio signal and outputs an electrical signal to a test circuit of the MEMS microphone.
The embodiment of the utility model provides a test circuit and equipment of MEMS microphone, test circuit of this MEMS microphone includes logic controller, amplifier circuit and A/D converter; amplifying the electric signal output by the MEMS microphone through an amplifying circuit, and outputting the amplified signal to an analog/digital converter; the analog/digital converter can convert the received amplified signal into a digital signal under the control of the logic controller, so that the logic controller can output the sensitivity detection result of the MEMS microphone according to the digital signal. The embodiment of the utility model provides a test circuit of MEMS microphone only can detect out the sensitivity of MEMS microphone through logic controller, amplifier circuit and analog/digital converter, and this detection circuitry simple structure is with low costs to when adopting this test circuit to test the MEMS microphone, easy operation, measuring accuracy and efficiency of software testing are high.
Drawings
Fig. 1 is a schematic structural diagram of a test circuit of a MEMS microphone according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a testing circuit of a MEMS microphone according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a testing circuit of a MEMS microphone according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of an amplifying circuit provided by the present invention;
fig. 5 is a schematic structural diagram of a test circuit of a MEMS microphone according to an embodiment of the present invention;
fig. 6 is a block diagram of a testing apparatus for a MEMS microphone according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Before discussing exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although a flowchart may describe the steps as a sequential process, many of the steps can be performed in parallel, concurrently or simultaneously. In addition, the order of the steps may be rearranged. The process may be terminated when its operations are completed, but may have additional steps not included in the figure. The processes may correspond to methods, functions, procedures, subroutines, and the like.
An embodiment of the utility model provides a test circuit of MEMS microphone, this test circuit of MEMS microphone can test the sensitivity of MEMS microphone. Fig. 1 is a schematic structural diagram of a test circuit of a MEMS microphone according to an embodiment of the present invention. As shown in fig. 1, the test circuit 100 of the MEMS microphone includes a logic controller 10, an amplifying circuit 20, and an analog/digital converter 30.
Wherein, the input terminal I20 of the amplifying circuit 20 is electrically connected with the output terminal O40 of the MEMS microphone 40, and the output terminal O20 of the amplifying circuit 20 is electrically connected with the input terminal I30 of the analog/digital converter 30; the amplifying circuit 20 amplifies the electrical signal output by the MEMS microphone 40 and outputs the amplified signal to the analog/digital converter 30; the enable end En30 of the a/d converter 30 is electrically connected to the enable signal output end En10 of the logic controller 10, and the output end O30 of the a/d converter 30 is electrically connected to the input end I30 of the logic controller 10; the analog/digital converter 30 receives an enable signal output from the logic controller 10, converts the amplified signal into a digital signal, and outputs the digital signal to the logic controller 10; the logic controller 10 receives the digital signal and outputs a sensitivity detection result.
Specifically, the MEMS microphone generally includes a silicon back plate and an acoustic diaphragm, the acoustic diaphragm and the silicon back electrode form a capacitor, and the MEMS microphone can deform the acoustic diaphragm by using a pressure gradient generated by a sound change, so as to change a capacitance value between the acoustic diaphragm and the silicon back electrode. Since sensitivity is an important index representing the sound-electricity conversion efficiency of the MEMS microphone, generally, sensitivity refers to an open circuit output voltage measured when the frequency of the MEMS microphone is at 1KHz under a constant sound pressure in a free sound field and a sound source is in a forward direction, and the higher the sensitivity of the MEMS microphone is, the higher the level of an electric signal provided to a sound console is, so that the MEMS microphone has a higher signal-to-noise ratio.
As shown in fig. 1, the sound is emitted by a corresponding sound emitting device 200, and the frequency of the sound emitted by the sound emitting device 200 may be, for example, the frequency of the sound to which the MEMS microphone 40 to be tested can respond; when the MEMS microphone 40 responds to the sound emitted from the sound emitting device 200, the capacitance of the capacitor formed by the acoustic diaphragm and the silicon back electrode in the MEMS microphone 40 changes, and generates a corresponding electrical signal; the electrical signal generated by the MEMS microphone 40 is input to the amplifying circuit 20 for signal amplification, so as to facilitate subsequent detection. Since the electric signal output by the microphone 40 is an analog signal, the electric signal is amplified by the amplifying circuit 20 to be an amplified electric signal, which is still an analog signal; and the logic controller 10 as a device capable of performing logic judgment, which is capable of processing the digital signal and outputting a judgment result; the analog/digital converter 30 can convert an analog signal into a digital signal by inputting the amplified signal output from the amplifying circuit 20 into the analog/digital converter 30; at this time, the logic controller 10 may control the analog-to-digital converter 30 to convert the amplified signal output from the amplifying circuit 20 into a digital signal, and input the digital signal to the logic controller 10, so that the logic controller 10 can output a sensitivity detection result for the MEMS microphone 40 based on the digital signal. The analog-to-digital converter 30 can be a high-speed analog-to-digital converter, so that the analog-to-digital converter 30 has high conversion efficiency and the test efficiency is improved.
Illustratively, a sensitivity threshold of the MEMS microphone 40, which may be, for example, 1000, may be stored in the logic controller 10, and the logic controller 10 detects whether the MEMS microphone is qualified by comparing the signal it receives with the pre-stored sensitivity threshold. If the signal received by the logic controller 10 is greater than the sensitivity threshold, it can be determined that the MEMS microphone 40 is a product with higher sensitivity, and a number 1 can be output to indicate that the MEMS microphone 40 is a qualified product; when the signal received by the logic controller 10 is smaller than the sensitivity threshold, it can be determined that the MEMS microphone 40 is a product with lower sensitivity, and a number 0 can be output to indicate that the MEMS microphone 40 is a defective product. Therefore, the unqualified MEMS microphone can be determined by testing the MEMS microphone, and the product yield of the MEMS microphone is obtained. The distances between the MEMS microphone and the sound generating device 200 are different, and the magnitudes of the signals responded by the MEMS microphone are different, so that the response signals at different distances can be adapted by adjusting the amplification factor of the amplifying circuit 20.
The utility model discloses can obtain the sensitivity testing result of MEMS microphone through logic controller, amplifier circuit and analog/digital converter, this test circuit simple structure of MEMS microphone, the cost is lower. When the MEMS microphone is tested by adopting the test circuit of the MEMS microphone, the test cost is low, the test flow is simple, the test precision is high, the test efficiency is high, and the production efficiency and the product yield are favorably improved.
Optionally, fig. 2 is a schematic structural diagram of a test circuit of another MEMS microphone according to an embodiment of the present invention. As shown in fig. 2, the amplifying circuit 20 of the test circuit 100 of the MEMS microphone may include a first-stage amplifying circuit 21, a second-stage amplifying circuit 22, and a third-stage amplifying circuit 23. The first-stage amplifying circuit 21, the second-stage amplifying circuit 22 and the third-stage amplifying circuit 23 are sequentially connected, and an input end I20 of the first-stage amplifying circuit 21 is electrically connected with an output end O40 of the MEMS microphone 40; the output terminal O20 of the third-stage amplification circuit 23 is electrically connected to the input terminal I30 of the analog/digital converter 30. In this way, after the electrical signal output by the MEMS microphone is input to the amplifying circuit 20, three-level amplification can be achieved, so as to improve the test accuracy.
Optionally, fig. 3 is a schematic structural diagram of a test circuit of another MEMS microphone according to an embodiment of the present invention. As shown in fig. 3, a first test point TP1 is disposed between the first-stage amplifier circuit 21 and the second-stage amplifier circuit 22, and a second test point TP2 is disposed between the second-stage amplifier circuit 22 and the third-stage amplifier circuit 23. At this time, the corresponding detectors may detect the amplified signals of the first stage amplifier circuit 21 and the second stage amplifier circuit 22 by collecting the signals of the first test point TP1 and the second test point TP2, and the amplified signal of the third stage amplifier circuit 23 may be detected by the logic controller 10.
In this way, before the MEMS microphone 40 is tested, the signals of the input terminal I20 of the amplifying circuit 20, the signal of the first test point TP1, the signal of the second test point TP2, and the signal of the output terminal O20 of the amplifying circuit 20 are collected to respectively detect whether the first-stage amplifying circuit 21, the second-stage amplifying circuit 22, and the third-stage amplifying circuit 23 are working normally, so as to prevent the first-stage amplifying circuit from working abnormally and affecting the test result, thereby further improving the test accuracy. The detector may be integrated in the logic controller 10, and the logic controller 10 detects the first-stage amplification circuit 21, the second-stage amplification circuit 22, and the third-stage amplification circuit 23.
For example, fig. 4 is a schematic circuit diagram of an amplifying circuit provided by the present invention. As shown in fig. 3 and 4, the first stage amplifier circuit 21 of the amplifier circuit 20 includes a first operational amplifier U1, a first capacitor C1, a second capacitor C2, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. A first end of the first capacitor C1 is electrically connected to the output O40 of the MEMS microphone 40, and a second end of the first capacitor C1 is electrically connected to the non-inverting input of the first operational amplifier U1 through the first resistor R1; a first end of the second resistor R2 is electrically connected to the first reference power Vref1, and a second end of the second resistor R2 is electrically connected to the non-inverting input terminal of the first operational amplifier U1 through the first resistor R1; the inverting input end of the first operational amplifier U1 is grounded through a third resistor R3 and a second capacitor C2 which are sequentially connected in series, and is electrically connected with the output end of the first operational amplifier U1 through a fourth resistor R4; the output end of the first operational amplifier U1 is electrically connected with the second-stage amplifying circuit 22; the reference signal terminal of the first operational amplifier U1 is electrically connected to a second reference power supply Vref 2. In this way, when the first-stage amplification circuit 21 receives the electrical signal output by the MEMS microphone 40, the first operational amplifier U1 cooperates with other devices in the first-stage amplification circuit 21 to perform first-stage amplification on the electrical signal, and outputs the first-stage amplified signal to the second-stage amplification circuit 22.
The third resistor R3 and the fourth resistor R4 in the first stage of amplifying circuit 21 are both adjustable resistors. In this way, the amplification factor of the amplifying circuit 20 can be changed by adjusting the resistance values of the third resistor R3 and the fourth resistor R4, i.e. the amplification factor N of the amplifying circuit 20 can be: n ═ 1+ R4/(R3+1/(2 × pi × f × C2))) so that the amplifying circuit 20 can adapt to response signals of different distances, making the test circuit of the MEMS microphone more flexible.
Illustratively, with continuing reference to fig. 3 and 4 in combination, the second stage amplifier circuit 22 of the amplifier circuit 20 includes a second operational amplifier U2, a third capacitor C3, a fifth resistor R5, and a sixth resistor R6; a first end of the third capacitor C3 is electrically connected with the output end of the first-stage amplifying circuit 21; a second end of the third capacitor C3 is electrically connected with the inverting input terminal of the second operational amplifier U2 through a fifth resistor R5; the inverting input terminal of the second operational amplifier U2 is also electrically connected to the output terminal of the second operational amplifier U2 through a fifth resistor R5; the non-inverting input end of the second operational amplifier U2 is electrically connected to the output end of the first stage amplifying circuit 21 through a sixth resistor R6; the output end of the second operational amplifier U2 is electrically connected with the input end of the third-stage amplifying circuit 23; the reference signal terminal of the second operational amplifier U2 is electrically connected to a second reference supply Vref 2. In this way, when the second-stage amplification circuit 22 receives the first-stage amplified signal output by the first-stage amplification circuit 21, the second operational amplifier U2 implements second-stage amplification in cooperation with other devices in the second-stage amplification circuit 22, and outputs the second-stage amplified signal to the third-stage amplification circuit 23.
Illustratively, with continuing reference to fig. 3 and 4 in combination, the third stage of the amplifying circuit 23 of the amplifying circuit 20 includes a third operational amplifier U3, a fourth capacitor C4, a seventh resistor R7 and an eighth resistor R8; a first end of the fourth capacitor C4 is electrically connected to the output end of the second stage amplifying circuit 22, and a second end of the fourth capacitor C4 is electrically connected to the inverting input end of the third operational amplifier U3 through a seventh resistor R7; the inverting input terminal of the third operational amplifier U3 is also electrically connected to the output terminal O20 of the third operational amplifier U3 through a seventh resistor R7; the non-inverting input terminal of the third operational amplifier U3 is electrically connected to the input terminal of the second stage amplifying circuit 22 through an eighth resistor R8; the output O20 of the third operational amplifier U3 is electrically connected to the input I30 of the analog-to-digital converter 30; the reference signal terminal of the third operational amplifier U3 is electrically connected to a second reference power supply Vref. In this way, when the third-stage amplification circuit 23 receives the second-stage amplified signal output by the second-stage amplification circuit 22, the third operational amplifier U3 implements third-stage amplification in cooperation with other devices in the third-stage amplification circuit 23, and outputs the third-stage amplified signal to the analog-to-digital converter 30.
In addition, corresponding voltage division resistors can be arranged between the amplifying circuits of all stages to realize the voltage division function. For example, a first voltage dividing resistor R9 is provided between the first-stage amplification circuit 21 and the second-stage amplification circuit 22, and a second voltage dividing resistor R10 is provided between the second-stage amplification circuit 22 and the third-stage amplification circuit 23.
It should be noted that fig. 4 is only an exemplary drawing of an embodiment of the present invention, and on the premise that the amplification function and the multiple adjustment function of the amplification circuit can be realized, the embodiment of the present invention does not specifically limit the specific circuit structure of the amplification circuit.
Optionally, in an embodiment of the present invention, the logic controller may be a programmable logic controller, and the programmable logic controller may be wirelessly connected with other devices through a communication protocol, or electrically connected with other devices through corresponding conductive wires. The Programmable logic controller may be, for example, a Field-Programmable Gate Array (FPGA). At the moment, the logic controller can send the sensitivity detection result output by the output end of the logic controller to an upper computer or display equipment and the like, so that the test personnel can conveniently operate and check the sensitivity detection result.
Optionally, fig. 5 is a schematic structural diagram of a test circuit of another MEMS microphone according to an embodiment of the present invention. As shown in fig. 5, the test circuit of the MEMS microphone further includes a display 50, and the display 50 is capable of receiving the sensitivity detection result output from the logic controller 10 and displaying the sensitivity detection result. Therefore, the sensitivity detection result can be visually displayed, so that the tester can directly obtain information such as the serial number and the qualification rate of qualified products.
The embodiment of the utility model provides a still provide a test equipment of MEMS microphone, the test equipment of this microphone include sound generating mechanism with the embodiment of the utility model provides a test circuit of MEMS microphone. The sound production device can provide audio signals for the MEMS microphone; when the MEMS microphone receives the audio signal, the MEMS microphone outputs an electric signal to a test circuit of the MEMS microphone, so that the test circuit of the MEMS microphone can detect the sensitivity of the MEMS microphone. Because this test equipment of MEMS microphone includes the utility model provides a test circuit of MEMS microphone, consequently this test equipment of MEMS microphone also has the utility model provides a beneficial effect that test circuit of MEMS microphone has, the same place can refer to above understanding, no longer redundantly hereafter.
For example, fig. 6 is a block diagram of a testing apparatus for a MEMS microphone according to an embodiment of the present invention. As shown in fig. 6, the testing apparatus 300 for a MEMS microphone includes the testing circuit 100 for a MEMS microphone and the sound generating device 200 provided by the embodiment of the present invention. After receiving the audio signal sent by the sound generating device 200, the MEMS microphone 40 can convert the audio signal into an electrical signal, and the test circuit 100 of the MEMS microphone detects the electrical signal output by the MEMS microphone 40 to obtain a sensitivity detection result of the MEMS microphone 40. In addition, the testing apparatus 300 for the MEMS microphone may further include a casing (not shown in the figure), a testing platform (not shown in the figure), and the like, which is not specifically limited by the embodiment of the present invention.
It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.
Claims (10)
1. A test circuit for a MEMS microphone, comprising: a logic controller, an amplifying circuit and an analog/digital converter;
the input end of the amplifying circuit is electrically connected with the output end of the MEMS microphone, and the output end of the amplifying circuit is electrically connected with the input end of the analog-to-digital converter; the amplifying circuit amplifies the electric signal output by the MEMS microphone and outputs the amplified signal to the analog/digital converter;
the enable end of the analog-to-digital converter is electrically connected with the enable signal output end of the logic controller, and the output end of the analog-to-digital converter is electrically connected with the input end of the logic controller; the analog-to-digital converter receives an enable signal output by the logic controller, converts the amplified signal into a digital signal and outputs the digital signal to the logic controller;
and the logic controller receives the digital signal and outputs a sensitivity detection result.
2. The test circuit of the MEMS microphone of claim 1, wherein the amplification circuit comprises a first stage amplification circuit, a second stage amplification circuit, and a third stage amplification circuit; the first-stage amplifying circuit, the second-stage amplifying circuit and the third-stage amplifying circuit are sequentially connected;
the input end of the first-stage amplifying circuit is electrically connected with the output end of the MEMS microphone; and the output end of the third-stage amplifying circuit is electrically connected with the input end of the analog-to-digital converter.
3. The test circuit of the MEMS microphone as claimed in claim 2, wherein a first test point is arranged between the first stage amplification circuit and the second stage amplification circuit, and a second test point is arranged between the second stage amplification circuit and the third stage amplification circuit;
the detector collects signals of the first test point and the second test point and detects the amplified signals of the first-stage amplifying circuit and the second-stage amplifying circuit.
4. The test circuit of a MEMS microphone according to claim 2, wherein the first stage amplification circuit comprises: the circuit comprises a first operational amplifier, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor and a fourth resistor;
the first end of the first capacitor is electrically connected with the output end of the MEMS microphone, and the second end of the first capacitor is electrically connected with the non-inverting input end of the first operational amplifier through the first resistor;
a first end of the second resistor is electrically connected with a first reference power supply, and a second end of the second resistor is electrically connected with a non-inverting input end of the first operational amplifier through the first resistor;
the inverting input end of the first operational amplifier is grounded through the third resistor and the second capacitor which are sequentially connected in series, and is electrically connected with the output end of the first operational amplifier through the fourth resistor; the output end of the first operational amplifier is electrically connected with the second-stage amplifying circuit; and the reference signal end of the first operational amplifier is electrically connected with a second reference power supply.
5. The test circuit of a MEMS microphone according to claim 4, wherein the third resistance and the fourth resistance are both adjustable resistors.
6. The test circuit of a MEMS microphone according to claim 2, wherein the second stage amplification circuit comprises: the second operational amplifier, the third capacitor, the fifth resistor and the sixth resistor;
the first end of the third capacitor is electrically connected with the output end of the first-stage amplifying circuit; a second end of the third capacitor is electrically connected with an inverting input end of the second operational amplifier through the fifth resistor; the inverting input end of the second operational amplifier is also electrically connected with the output end of the second operational amplifier through the fifth resistor;
the non-inverting input end of the second operational amplifier is electrically connected with the output end of the first-stage amplifying circuit through the sixth resistor; the output end of the second operational amplifier is electrically connected with the input end of the third-stage amplifying circuit; and the reference signal end of the second operational amplifier is electrically connected with a second reference power supply.
7. The test circuit of a MEMS microphone according to claim 2, wherein the third stage amplification circuit comprises: the third operational amplifier, the fourth capacitor, the seventh resistor and the eighth resistor;
a first end of the fourth capacitor is electrically connected with an output end of the second-stage amplifying circuit, and a second end of the fourth capacitor is electrically connected with an inverting input end of the third operational amplifier through the seventh resistor; the inverting input end of the third operational amplifier is also electrically connected with the output end of the third operational amplifier through the seventh resistor;
the non-inverting input end of the third operational amplifier is electrically connected with the input end of the second-stage amplifying circuit through the eighth resistor; the output end of the third operational amplifier is electrically connected with the input end of the analog-to-digital converter; and the reference signal end of the third operational amplifier is electrically connected with a second reference power supply.
8. The test circuit of a MEMS microphone according to any one of claims 1 to 7, further comprising: a display;
and the display receives the sensitivity detection result output by the logic controller and displays the sensitivity detection result.
9. The test circuit of a MEMS microphone according to any one of claims 1 to 7, wherein the logic controller is a programmable logic controller.
10. A test apparatus for a MEMS microphone, comprising: a sound emitting device and a test circuit of the MEMS microphone according to any one of claims 1 to 9;
wherein the sound generating device provides an audio signal for the MEMS microphone; the MEMS microphone receives the audio signal and outputs an electrical signal to a test circuit of the MEMS microphone.
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| CN201922311643.9U CN210694365U (en) | 2019-12-20 | 2019-12-20 | Test circuit and equipment of MEMS microphone |
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| CN201922311643.9U CN210694365U (en) | 2019-12-20 | 2019-12-20 | Test circuit and equipment of MEMS microphone |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113543007A (en) * | 2021-07-06 | 2021-10-22 | 昆山鑫润利自动化科技有限公司 | Flexible circuit board microphone sensitivity simulation test circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113543007A (en) * | 2021-07-06 | 2021-10-22 | 昆山鑫润利自动化科技有限公司 | Flexible circuit board microphone sensitivity simulation test circuit |
| CN113543007B (en) * | 2021-07-06 | 2023-11-10 | 昆山鑫润利自动化科技有限公司 | Flexible circuit board microphone sensitivity analog test circuit |
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