Microphone circuit

Abstract

Provided in the present application is a microphone circuit, comprising: a charge pump module, which is connected to a first terminal of a microphone, and used for receiving a preset first voltage, generating a first bias voltage on the basis of the first voltage and outputting same to the microphone; an amplification module, which is connected to a second terminal of the microphone, and used for receiving a voltage signal output by the microphone, amplifying the voltage signal and outputting same as an output signal of the microphone circuit; and a voltage division module, which is connected to the second terminal of the microphone and the amplification module, and used for receiving the first voltage, dividing the first voltage to generate a second bias voltage and outputting same to the microphone, and outputting the second bias voltage as a bias voltage of the amplification module to the amplification module. In the microphone circuit of the present application, the first bias voltage and the second bias voltage change along with the first voltage, that is, regulating any bias voltage causes the other bias voltage to change accordingly, thereby solving the problem of sensitivity offset of MEMS microphones caused by the change in the difference between two bias voltages due to the regulation of any bias voltage.

Description

microphone circuit [Technical Field]

[0001] This application relates to the field of circuit technology, and more particularly to a microphone circuit. [Background Technology]

[0002] The MEMS microphone circuit mainly includes a MEMS microphone (Microelectro Mechanical Systems) and an ASIC (Application-Specific Integrated Circuit) module. The two are electrically connected to convert sound signals into electrical signals, thereby realizing the function of a microphone. Specifically, the ASIC module provides a high-voltage high-bias voltage and a low-voltage low-bias voltage to the MEMS microphone to drive the MEMS microphone to convert sound signals into electrical signals.

[0003] The sensitivity of a MEMS microphone is directly proportional to the difference between its high and low bias voltages. In related technologies, the high and low bias voltages of a MEMS microphone are independent; adjusting either bias voltage will change the difference between them, thus affecting the microphone's sensitivity. However, attempting to maintain this difference by separately adjusting the high and low bias voltages increases the complexity of the circuit design. When a MEMS microphone operates over a wide power supply voltage range, the power supply voltage fluctuates. Therefore, to maintain the microphone's AOP (Acoustic Overload Point), the output voltage of the MEMS microphone circuit needs to be adjusted by changing the low bias voltage. This ensures the output voltage is maintained at half the power supply voltage, resulting in a better AOP for the entire MEMS microphone circuit. This is because the AOP of a MEMS microphone circuit is greatest when its output voltage is half the power supply voltage. However, changing the low bias voltage also alters the difference between the high and low bias voltages, causing a shift in the microphone's sensitivity.

[0004] Therefore, it is necessary to provide a new microphone circuit to solve the above-mentioned technical problems. [Summary of the Invention]

[0005] The purpose of this application is to provide a microphone circuit to solve the above-mentioned technical problems.

[0006] The technical solution of this application is as follows:

[0007] This application provides a microphone circuit, including:

[0008] A charge pump module is connected to the first end of an external microphone to receive a preset first voltage and generate a first bias voltage required for the microphone to operate, which is then output to the microphone.

[0009] An amplification module, connected to the second end of the microphone, is used to receive the voltage signal output by the microphone and amplify the voltage signal as the output signal of the microphone circuit.

[0010] The voltage divider module is connected to the second end of the microphone and the amplification module. It is used to receive the first voltage, divide the first voltage to generate a second bias voltage required for the microphone to work and output it to the microphone, and output the second bias voltage as the bias voltage of the amplification module to the amplification module.

[0011] In some embodiments, the charge pump module includes at least one cascaded charge pump, the output of each charge pump is connected to the input of the next charge pump, the input of the first charge pump is grounded, and the output of the last charge pump is connected to the first end of the microphone.

[0012] Wherein, the reference voltage of the first stage charge pump is the first voltage, and the reference voltage of each stage charge pump after the first stage charge pump is a preset charge pump reference voltage.

[0013] In some embodiments, the ratio of the second bias voltage output by the voltage divider module to the first voltage received by the voltage divider module is equal to the ratio of the output voltage of the first-stage charge pump to the first voltage received by the first-stage charge pump.

[0014] In some embodiments, each charge pump includes an enable terminal, and the enable terminal of each charge pump is used to receive a corresponding enable signal, and each enable signal is used to control the corresponding charge pump.

[0015] When the enable signal is at the first level, the charge pump adjusts the received input voltage according to the received reference voltage and outputs the adjusted input voltage as the output voltage; when the enable signal is at the second level, the charge pump outputs the input voltage as the output voltage.

[0016] In some embodiments, the amplification module includes at least one stage of coupled amplifier, the output of each stage amplifier is connected to the input of the next stage amplifier, and the input of the first stage amplifier is connected to the second terminal of the microphone and the voltage divider module, respectively. The output of the final stage amplifier is used to output the output signal of the microphone circuit.

[0017] In some embodiments, the microphone circuit further includes:

[0018] The low-dropout linear regulator module is used to connect to a power supply, regulate the power supply voltage to obtain the first voltage, and output the first voltage to the charge pump module and the voltage divider module.

[0019] In some embodiments, the low-dropout linear regulator module includes:

[0020] A linear voltage regulator unit is used to connect to the power supply and to regulate the power supply voltage to output the first voltage.

[0021] The feedback unit is used to receive the first voltage and perform voltage division processing on the first voltage to generate a feedback voltage.

[0022] The linear voltage regulator unit is also used to receive the feedback voltage and a preset first reference voltage, and to linearly adjust the first voltage according to the feedback voltage and the first reference voltage.

[0023] In some embodiments, the low-dropout linear regulator module further includes:

[0024] The voltage divider and filter unit is used to connect to the power supply, divide and filter the power supply voltage, and output the first reference voltage.

[0025] In some embodiments, the microphone is a MEMS microphone.

[0026] The beneficial effects of this application are as follows: The microphone circuit provided in this application inputs a first voltage to a charge pump module and a voltage divider module to obtain a first bias voltage and a second bias voltage. In this way, the first bias voltage output by the charge pump module and the second bias voltage output by the voltage divider module both change with the first voltage, thereby achieving synchronous changes in the first bias voltage and ensuring that the difference between the first bias voltage and the second bias voltage remains constant. The microphone circuit provided in this application can simultaneously adjust the first bias voltage and the second bias voltage by adjusting the first voltage; that is, adjusting either bias voltage will cause the other bias voltage to change accordingly. This solves the technical problem that the difference between the first bias voltage and the second bias voltage is easily altered by adjusting either bias voltage, leading to a shift in the sensitivity of the MEMS microphone. In this way, when the power supply voltage of the microphone circuit changes, the second bias voltage can be adjusted by changing the first voltage. In turn, by adjusting the second bias voltage, the voltage of the output signal of the amplification module is adjusted to about half of the power supply voltage. This ensures that the entire microphone circuit always has a large acoustic overload point when the power supply voltage changes. Furthermore, because the first bias voltage also changes with the second bias voltage, the microphone circuit can always maintain a constant difference between the first bias voltage and the second bias voltage, so that the microphone sensitivity will not shift due to the adjustment of the acoustic overload point. [Attached Image Description]

[0027] Figure 1 is a schematic diagram of a microphone circuit provided in an embodiment of this application;

[0028] Figure 2 is another schematic diagram of the microphone circuit provided in an embodiment of this application;

[0029] Figure 3 shows another schematic diagram of the microphone circuit provided in an embodiment of this application;

[0030] Figure 4 shows another schematic diagram of the microphone circuit provided in an embodiment of this application;

[0031] Figure 5 shows another schematic diagram of the microphone circuit provided in an embodiment of this application;

[0032] Figure 6 shows another schematic diagram of the microphone circuit provided in an embodiment of this application.

Detailed Implementation Methods

[0033] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0034] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.

[0035] This application provides a microphone circuit. Figure 1 is a schematic diagram of a microphone circuit provided in this application. As shown in Figure 1, the microphone circuit provided in this application includes a charge pump module, a voltage divider module, and an amplification module.

[0036] The charge pump module is connected to the first end of an external microphone to receive a preset first voltage and generate a first bias voltage required for the microphone to operate, which is then output to the microphone. Optionally, the charge pump module is used to boost the first voltage to obtain a high-voltage first bias voltage. The output end of the charge pump is connected to the first end of the microphone to output the first bias voltage to the first end of the microphone. The charge pump module receives the first voltage to obtain the first bias voltage based on the first voltage.

[0037] The voltage divider module is connected to the second terminal of the microphone and the amplification module. It receives a first voltage, divides the first voltage to generate a second bias voltage required for the microphone to operate, and outputs this second bias voltage to the microphone. It also outputs this second bias voltage as the bias voltage for the amplification module. Optionally, the output terminal of the voltage divider module is connected to both the second terminal of the microphone and the input terminal of the amplification module to output a low-voltage second bias voltage. The input terminal of the voltage divider module receives the first voltage and divides it to obtain the second bias voltage.

[0038] The amplification module is connected to the second terminal of the microphone to receive the voltage signal output by the microphone and amplify it as the output signal of the microphone circuit. Optionally, the input terminal of the amplification module is connected to the second terminal of the microphone to receive the voltage signal output by the microphone. The input terminal of the amplification module is also connected to the output terminal of the voltage divider module to receive the bias voltage output by the voltage divider module. This bias voltage is the input DC voltage of the amplification module. The output terminal of the amplification module amplifies and outputs the voltage signal output by the microphone. For the microphone circuit, when the voltage of the output signal of the amplification module reaches half of the power supply voltage of the microphone circuit, the entire microphone circuit has the maximum AOP (Acoustic Overload Point). In view of this, this application uses the second bias voltage as the bias voltage of the amplification module, so that when the power supply voltage of the microphone circuit changes, the second bias voltage can be changed by adjusting the first voltage, thereby adjusting the voltage of the output signal of the amplification module so that it can always maintain about half of the power supply voltage of the microphone circuit.

[0039] In some preferred embodiments, the microphone circuit provided in this application uses a MEMS microphone as the external microphone.

[0040] In one implementation, the microphone circuit provided in this application embodiment receives a first voltage through the signal input port. The first bias voltage output by the charge pump module is: VH = Vref × K + V1, and the second bias voltage output by the voltage divider module is: VL = V1 × H. The difference between the first bias voltage and the second bias voltage is: VH - VL = Vref × K + V1 - V1 × H. Wherein, VH represents the first bias voltage, Vref represents the reference voltage of the charge pump module, K represents the efficiency factor of the charge pump module, V1 represents the first voltage, VL represents the second bias voltage, and H represents the voltage division coefficient of the voltage divider module. Therefore, the microphone circuit provided in this application embodiment can control the difference between the first bias voltage and the second bias voltage to follow the change of the first voltage by adjusting the value of the voltage divider coefficient H. When the voltage divider coefficient of the voltage divider module is 1, the difference between the first bias voltage and the second bias voltage will always remain unchanged. Thus, the sensitivity of the MEMS microphone does not shift with the bias voltage in the microphone circuit. When the power supply voltage of the microphone circuit changes, the microphone circuit controls the output voltage of the amplification module to change synchronously by adjusting the second bias voltage. At this time, the sensitivity of the MEMS microphone will not shift with the change of the power supply voltage.

[0041] In another implementation, in the microphone circuit provided in this application embodiment, the charge pump module receives a first voltage through a reference voltage input port, while the signal input port of the charge pump module receives an input voltage provided by an external circuit. At this time, the first bias voltage output by the charge pump module is VH = V1 × K + V0, and the second bias voltage output by the voltage divider module is VL = V1 × H. The difference between the first bias voltage and the second bias voltage is VH - VL = V1 × K + V0 - V1 × H. Wherein, VH represents the first bias voltage, V1 represents the first voltage (i.e., the reference voltage of the charge pump module), K represents the efficiency factor of the charge pump module, V0 represents the input voltage provided by the external circuit, VL represents the second bias voltage, and H represents the voltage division coefficient of the voltage divider module. Therefore, in this embodiment, the difference between the first and second bias voltages, following the change in the first voltage, is determined by the difference between the efficiency factor K of the charge pump module and the voltage division coefficient H of the voltage divider module. Furthermore, when the difference between the efficiency factor K of the charge pump module and the voltage division coefficient H of the voltage divider module is zero, the difference between the first and second bias voltages will remain constant. Thus, in this microphone circuit, the sensitivity of the MEMS microphone does not shift with the bias voltage. When the power supply voltage of the microphone circuit changes, the microphone circuit controls the output voltage of the amplification module to change synchronously by adjusting the second bias voltage. At this time, the sensitivity of the MEMS microphone will not shift with the change in the power supply voltage. Optionally, this application embodiment does not limit the type or structure of the external circuit, as long as the external circuit can be applied to the microphone circuit.

[0042] In one implementation, when the microphone operates within a wide power supply voltage range, such as 0.9V to 3.6V, this embodiment can adjust the value of the second bias voltage by adjusting the first voltage when the power supply voltage changes. Since the second bias voltage is also the input DC voltage of the amplification module, changing the second bias voltage will also adjust the output signal voltage of the amplification module, ensuring it remains at half the power supply voltage of the microphone circuit. This ensures the entire microphone circuit always has a large acoustic overload point. Furthermore, because the first bias voltage also changes with the second bias voltage, the microphone circuit can maintain a constant difference between the first and second bias voltages, preventing the microphone's sensitivity from shifting due to adjustments in the acoustic overload point.

[0043] It is understood that in this embodiment, the charge pump module, voltage divider module, and amplification module are electrically connected to the external MEMS microphone. Furthermore, this embodiment does not limit the source of the first voltage. For example, the first voltage can be set to the power supply voltage of the MEMS microphone circuit. This way, when the MEMS microphone operates over a wide power supply range, the first and second bias voltages will change with the power supply voltage without significantly affecting the sensitivity of the MEMS microphone. For example, the first voltage can also be provided by a voltage regulator circuit, thereby providing the MEMS microphone circuit with a first and second bias voltage that have a good power supply rejection ratio (PSRR). For example, the first voltage can also be provided by a voltage regulator circuit, which regulates the power supply voltage to obtain the first voltage. The above examples are only used to illustrate that this embodiment does not limit the source of the first voltage, and do not imply that the first voltage can only be obtained through the above three examples.

[0044] It is understood that no specific restrictions are set on the structure of the voltage divider module in this application embodiment. This is because the voltage divider module belongs to a relatively mature part of the existing technical field, and the focus and goal of this application embodiment is not to innovate or explore the specific structure of these two units. For example, a basic voltage divider module can be configured to include a voltage divider or a voltage divider circuit composed of resistive elements.

[0045] The microphone circuit provided in this application embodiment can simultaneously adjust the first bias voltage and the second bias voltage by adjusting the first voltage. That is, when either bias voltage is adjusted, the other bias voltage will change accordingly. This solves the technical problem that the difference between the first bias voltage and the second bias voltage is easily changed by adjusting either bias voltage, which can cause the sensitivity of the MEMS microphone to shift.

[0046] The microphone circuit provided in this application is applied to a microphone circuit with adjustable power supply voltage. When the power supply voltage of the microphone circuit changes, the second bias voltage can be adjusted by changing the first voltage. In turn, by adjusting the second bias voltage, the voltage of the output signal of the amplification module can be adjusted to about half of the power supply voltage. Since the first bias voltage also changes with the second bias voltage, the microphone circuit of this application can ensure that the microphone circuit always maintains a good AOP when the power supply voltage changes, and also ensure that the sensitivity of the microphone does not shift.

[0047] In some preferred embodiments, Figure 2 is another schematic diagram of the microphone circuit provided in the embodiments of this application. As shown in Figure 2, the charge pump module includes at least one cascaded charge pump, i.e., cascaded charge pump 1 to charge pump i, i≥1. The output terminal of each charge pump is connected to the input terminal of the next charge pump, and the input terminal of the first charge pump, i.e., charge pump 1, is grounded to GND. The output terminal of the last charge pump, i.e., charge pump i, is connected to the first terminal of the microphone. The reference voltage of the first charge pump is a first voltage, and the reference voltages of each charge pump after the first charge pump are all preset charge pump reference voltages. Optionally, in the microphone circuit shown in Figure 2, the first bias voltage output by the charge pump module is: VH=V1×K1+V ref ×K2+V ref ×K3+…+V ref ×K N The second bias voltage output by the voltage divider module is: VL = V1 × H. The difference between the first bias voltage and the second bias voltage is: VH - VL = V1 × K1 - V1 × H + V ref ×K2+V ref ×K3+…+V ref ×K N Where VH represents the first bias voltage, V1 represents the first voltage, i.e., the reference voltage of the first-stage charge pump, and V... ref This represents the preset charge pump reference voltage. For each stage of the charge pump after the first stage, the preset charge pump reference voltage is fixed and provided by external circuitry such as a linear voltage regulator circuit. K i Let K1 represent the efficiency factor of the i-th stage charge pump, 1 ≤ i ≤ N, and N be the number of cascaded stages of the charge pump module. VL represents the second bias voltage, and H represents the voltage division coefficient of the voltage divider module. Therefore, the microphone circuit of this embodiment can determine the magnitude of the difference between the first bias voltage and the second bias voltage following the change of the first voltage by the difference between the efficiency factor K1 of the first stage charge pump and the voltage division coefficient H of the voltage divider module.

[0048] In some embodiments, in the microphone circuit provided in this application, the ratio of the second bias voltage output by the voltage divider module to the first voltage received by the voltage divider module is equivalent to the ratio of the output voltage of the first-stage charge pump to the first voltage received by the first-stage charge pump. Optionally, the ratio of the second bias voltage output by the voltage divider module to the first voltage received by the voltage divider module is the voltage division coefficient H of the voltage divider module. The signal input terminal of the first-stage charge pump is grounded, and the first voltage is used as a reference voltage input to the first-stage charge pump, that is, the first-stage charge pump has no input voltage, and its output voltage is V1×K1. The ratio of the output voltage of the first-stage charge pump to the first voltage received by the first-stage charge pump is K1, and the difference between the first bias voltage and the second bias voltage is: VH-VL=V1×K1-V1×H+V ref ×K2+V ref ×K3+…+V ref ×K N When H = K1, VH - VL = V ref ×K2+V ref ×K3+…+V ref ×K N That is, the difference between the first bias voltage and the second bias voltage is a fixed value and will not change due to the change of the first voltage.

[0049] The microphone circuit provided in this application embodiment uses a first voltage as the reference voltage input for the first-stage charge pump. In this way, the difference between the first bias voltage and the second bias voltage will be determined by the difference between the efficiency factor K1 of the first-stage charge pump and the voltage division coefficient H of the voltage divider module. When the efficiency factor K1 of the first-stage charge pump is equal to the voltage division coefficient H of the voltage divider module, the difference between the first bias voltage and the second bias voltage will not change with the first voltage. This achieves that the sensitivity of the MEMS microphone does not shift with the bias voltage, and solves the problem that the difference between the first bias voltage and the second bias voltage is easily changed by the adjustment of either bias voltage, which can cause the sensitivity of the MEMS microphone to shift.

[0050] In some embodiments, in the microphone circuit provided by this application, each charge pump includes an enable terminal. The enable terminal of each charge pump is used to receive a corresponding enable signal, and each enable signal is used to control its corresponding charge pump. Specifically, when the enable signal is at a first level, the charge pump adjusts its received input voltage according to a received reference voltage and outputs the adjusted input voltage as its output voltage. At this time, the output voltage of the charge pump is V. out =V in +V ref ×K. When the enable signal is at the second level, the charge pump outputs the input voltage as its output voltage, and the output voltage of the charge pump at this time is V. out =V inOptionally, the first level is either a high level or a low level, and the second level is either a high level or a low level.

[0051] It is understood that the embodiments of this application do not limit the source of the enable signal. For example, the enable signal can be generated by existing level generation circuits.

[0052] In some embodiments, FIG3 shows another schematic diagram of the microphone circuit provided in this application embodiment. As shown in FIG3, the amplification module includes at least one coupled amplifier, namely amplifier 1 to amplifier j, j≥1, which are coupled together. The output terminal of each amplifier stage is connected to the input terminal of the next amplifier stage. The input terminal of the first amplifier stage, i.e., amplifier 1, is connected to the second terminal of the microphone and the voltage divider module, respectively. The output terminal of the final amplifier stage, i.e., amplifier j, is used to output the output signal of the microphone circuit. The microphone circuit provided in this application embodiment can significantly improve the circuit gain and stabilize the signal processing process through multi-stage amplification. It can also be flexibly configured to adapt to different scenarios, optimize the overall circuit performance, and enable the output signal to better meet subsequent requirements.

[0053] As one implementation method, the microphone circuit provided in this application embodiment includes an amplifier module with two-stage coupling, thereby amplifying and outputting the voltage signal output by the microphone in two stages.

[0054] In some embodiments, FIG4 shows another schematic diagram of the microphone circuit provided in the present application. As shown in FIG4, the microphone circuit of the present application further includes a low dropout linear regulator module. The input terminal of the low dropout linear regulator module is used to connect to the power supply VDD, and the output terminal is connected to the input terminal of the charge pump module and the input terminal of the voltage divider module, respectively. In this way, the power supply voltage is regulated by linear adjustment to obtain a first voltage, and the first voltage is output to the charge pump module and the voltage divider module.

[0055] The microphone circuit provided in this application embodiment has a first voltage obtained by processing the power supply voltage by a low dropout linear regulator module. In this way, when the microphone circuit operates in a wide power supply voltage range, the first voltage will also change with the power supply voltage. Consequently, the AOP of the microphone circuit changes synchronously with the power supply voltage change, and the sensitivity of the microphone circuit will not shift at this time.

[0056] In some embodiments, FIG5 shows another schematic diagram of the microphone circuit provided in the present application. As shown in FIG5, the low dropout linear regulator module includes a linear regulator unit and a feedback unit.

[0057] The input terminal of the linear voltage regulator unit is connected to the power supply VDD, and the output terminal is connected to the charge pump module and the voltage divider module, respectively, thereby regulating the power supply voltage and outputting a first voltage to the charge pump module and the voltage divider module. A feedback unit is connected to the linear voltage regulator unit and is used to receive the first voltage and perform voltage divider processing to generate a feedback voltage. Further, the linear voltage regulator unit is also used to receive the feedback voltage and a preset first reference voltage, and linearly adjust the first voltage according to the feedback voltage and the first reference voltage, thereby enabling timely adjustment of the first voltage after changes in the power supply voltage. Optionally, in the microphone circuit provided in this application embodiment, the first voltage can be adjusted by adjusting the value of the first reference voltage and / or the voltage division coefficient of the feedback unit.

[0058] It should be noted that in the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after it are in an "or" relationship.

[0059] It is understood that no specific restrictions are set on the specific structures of the linear voltage regulator unit and the feedback unit in this application embodiment. This is because both the linear voltage regulator unit and the feedback unit belong to relatively mature parts in the existing technical field, and the focus and goal of this application embodiment is not to innovate or explore the specific structures of these two units in depth. For example, a basic linear voltage regulator unit can be configured to include an operational amplifier and a transistor. The non-inverting input terminal and the inverting input terminal of the operational amplifier are used to receive the feedback voltage and the first reference voltage, respectively. The output terminal of the operational amplifier is connected to the gate of the transistor, the source of the transistor is connected to the power supply, and the drain of the transistor outputs the first voltage. A basic feedback unit can be configured as a voltage divider circuit / voltage divider to divide the first voltage and output the result as the feedback voltage to the operational amplifier. The above is only one structure of the linear voltage regulator unit and the feedback unit, and does not mean that the functions of the linear voltage regulator unit and the feedback unit can only be achieved through this structure in this application embodiment.

[0060] In some embodiments, FIG6 shows another schematic diagram of the microphone circuit provided in this application embodiment. As shown in FIG6, the low dropout linear regulator module further includes a voltage divider filter unit. The input terminal of the voltage divider filter unit is connected to the power supply VDD, and the output terminal is connected to the linear regulator unit, thereby dividing and filtering the power supply voltage to output a first reference voltage. Optionally, the first reference voltage also changes with the power supply voltage, and the first reference voltage obtained by dividing and filtering the power supply voltage changes proportionally to the power supply voltage, so that the first voltage output by the linear regulator unit also changes proportionally to the power supply voltage. Moreover, the first reference voltage after voltage divider filtering has a certain PSRR (Power Supply Rejection Ratio), so the first voltage regulated by the first reference voltage can also have a good power supply rejection ratio.

[0061] In one implementation, in the microphone circuit of this application, the first voltage output by the low-dropout linear regulator module 50 is 0.95 times the power supply voltage. The voltage division coefficient of the voltage divider module and the efficiency factor of the charge pump module 10 are both 0.5. At this time, the second bias voltage VL = 0.95VDD × 0.5 = 0.475VDD, where VDD represents the power supply voltage and VL represents the second bias voltage. Therefore, in this microphone circuit, regardless of how the power supply voltage changes, the second bias voltage is always close to 0.5 times the power supply voltage. Since the second bias voltage is the input DC voltage of the amplification module, the voltage of the output signal of the amplification module 30 will always be close to 0.5 times VDD. It should be noted that the relationship between the first voltage output by the low-dropout linear regulator module and the power supply voltage is determined by the specific design and performance of the low-dropout linear regulator module.

[0062] It is understood that no specific restrictions are set on the structure of the voltage divider filter unit in this embodiment of the application. This is because the voltage divider filter unit is a relatively mature part of the existing technical field, and the focus and goal of this embodiment of the application is not to innovate or explore the specific structure of these two units. For example, a voltage divider filter unit can be configured to include a voltage divider circuit / device and a filter circuit / device.

[0063] The above description is merely an embodiment of this application. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this application, but these improvements all fall within the protection scope of this application.

Claims

1. A microphone circuit, characterized in that, include: A charge pump module is connected to the first end of an external microphone to receive a preset first voltage and generate a first bias voltage required for the microphone to operate, which is then output to the microphone. An amplification module, connected to the second end of the microphone, is used to receive the voltage signal output by the microphone and amplify the voltage signal as the output signal of the microphone circuit. The voltage divider module is connected to the second end of the microphone and the amplification module. It is used to receive the first voltage, divide the first voltage to generate a second bias voltage required for the microphone to work and output it to the microphone, and output the second bias voltage as the bias voltage of the amplification module to the amplification module.

2. The microphone circuit according to claim 1, characterized in that, The charge pump module includes at least one cascaded charge pump, the output of each charge pump is connected to the input of the next charge pump, the input of the first charge pump is grounded, and the output of the last charge pump is connected to the first end of the microphone. Wherein, the reference voltage of the first stage charge pump is the first voltage, and the reference voltage of each stage charge pump after the first stage charge pump is a preset charge pump reference voltage.

3. The microphone circuit according to claim 2, characterized in that, The ratio of the second bias voltage output by the voltage divider module to the first voltage received by the voltage divider module is equal to the ratio of the output voltage of the first-stage charge pump to the first voltage received by the first-stage charge pump.

4. The microphone circuit according to claim 2, characterized in that, Each charge pump includes an enable terminal, and the enable terminal of each charge pump is used to receive a corresponding enable signal. Each enable signal is used to control the corresponding charge pump. When the enable signal is at the first level, the charge pump adjusts the received input voltage according to the received reference voltage and outputs the adjusted input voltage as the output voltage; when the enable signal is at the second level, the charge pump outputs the input voltage as the output voltage.

5. The microphone circuit according to claim 1, characterized in that, The amplification module includes at least one stage of coupled amplifier. The output of each stage amplifier is connected to the input of the next stage amplifier. The input of the first stage amplifier is connected to the second terminal of the microphone and the voltage divider module, respectively. The output of the final stage amplifier is used to output the output signal of the microphone circuit.

6. The microphone circuit according to claim 1, characterized in that, Also includes: The low-dropout linear regulator module is used to connect to a power supply, regulate the power supply voltage to obtain the first voltage, and output the first voltage to the charge pump module and the voltage divider module.

7. The microphone circuit according to claim 6, characterized in that, The low-dropout linear regulator module includes: A linear voltage regulator unit is used to connect to the power supply and to regulate the power supply voltage to output the first voltage. The feedback unit is used to receive the first voltage and perform voltage division processing on the first voltage to generate a feedback voltage. The linear voltage regulator unit is also used to receive the feedback voltage and a preset first reference voltage, and to linearly adjust the first voltage according to the feedback voltage and the first reference voltage.

8. The microphone circuit according to claim 7, characterized in that, The low-dropout linear regulator module also includes: The voltage divider and filter unit is used to connect to the power supply, divide and filter the power supply voltage, and output the first reference voltage.

9. The microphone circuit according to claim 1, characterized in that, The microphone is a MEMS microphone.

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