Semiconductor integrated circuit device and microphone module using the same

Abstract

Provided is a semiconductor integrated circuit device capable of receiving a signal of a MEMS transducer, the semiconductor integrated circuit device including: a power supply circuit 11 for a MEMS transducer 2; an input amplifier 12 for receiving and amplifying a signal from the MEMS transducer 2; a line driver 13 which has an input terminal, amplifies an output of the input amplifier 12, and enables driving a load connected to an output terminal T3; and the output terminal T3 for outputting an output of the line driver 13. The power supply circuit 11, the input amplifier 12, and the line driver 13 are integrally formed on a semiconductor substrate, and a gain setting circuit 14 for determining a gain of the line driver 13 and a direct-current potential of the output terminal T3 is connected to the input terminal of the line driver 13.

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor integrated circuit device that uses the output of a MEMS transducer as a signal source, and a microphone module using the same. [Background technology]

[0002] As shown in FIG. 12, a conventional in-vehicle microphone (microphone unit) generally comprises a MEMS transducer microphone module 82 consisting of a MEMS transducer and an amplifier, a regulator 81 that supplies a bias voltage to the MEMS transducer microphone module 82, a two-wire line driver 83, and a gain adjustment circuit 84 that adjusts the gain of the two-wire line driver 83 (see, for example, Patent Document 1).

[0003] When a MEMS transducer microphone module is used as a microphone module, its power supply voltage is generally approximately 3.3V at most. However, when used in an automotive application, the maximum voltage for a microphone is approximately 8V, so peripheral components such as a regulator 81 are required to operate the MEMS transducer microphone module. Furthermore, since strict gain accuracy is required for applications such as noise cancellation, a MEMS transducer microphone module with controlled gain must be used. Furthermore, to adjust the gain after assembling the microphone unit, adjustments must be made using a trimmer resistor mechanically or by laser trimming the resistor on the board.

[0004] For this reason, in the in-vehicle microphone, the regulator 81, MEMS transducer microphone module 82, two-wire line driver 83, and gain adjustment circuit 84 are each individual components, and these components are arranged on a board, allowing assembly while adjusting characteristics such as gain. In Figure 12, 85 is a phantom power supply, R L is the output load resistance, and OUT is the signal output. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-511219 Summary of the Invention [Problem to be solved by the invention]

[0006] When each individual component is placed on a board as described above, RF noise RFN, as shown in Figure 12, is easily transmitted to the wiring between the components. This requires measures such as connecting filters to remove RF noise between each component, although this is not shown. As a result, the number of components increases, and in a configuration where each component is assembled on a board, an increase in the mounting area is unavoidable. Furthermore, there is the problem that the number of assembly steps required for gain adjustment and other purposes increases, leading to a significant increase in costs.

[0007] Therefore, an object of the present disclosure is to provide a semiconductor integrated circuit device that uses the output of a MEMS transducer as a signal source, which allows for easy assembly of a microphone module that is less susceptible to RF noise, and a microphone module using the same. [Means for solving the problem]

[0008] In one aspect of the present disclosure, a semiconductor integrated circuit device includes a power supply circuit for a MEMS transducer, an input amplifier that receives and amplifies a signal from the MEMS transducer, a line driver that amplifies an output of the input amplifier and enables driving of a load connected to an output terminal, and the output terminal that outputs an output of the line driver. a voltage adjustment circuit that adjusts the voltage of the power supply circuit; a first memory that stores a voltage value adjusted by the voltage adjustment circuit; a gain adjuster that adjusts the gain of the input amplifier; a second memory that stores the gain adjusted by the gain adjuster; and a memory control terminal connected to the first memory and the second memory. Including A semiconductor integrated circuit device including The power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate, and a gain setting circuit that determines the gain of the line driver and the DC potential of the output terminal is connected to the input terminal of the line driver. The memory control terminal is a single external terminal among external terminals provided on the semiconductor integrated circuit device that is used to control both the first memory and the second memory and to read and write data from and to the first memory and the second memory. do.

[0009] In another aspect of the present disclosure, a semiconductor integrated circuit device includes a power supply circuit for a MEMS transducer, an input amplifier that receives and amplifies a signal from the MEMS transducer, a line driver that amplifies an output of the input amplifier and enables driving of a load connected to an output terminal, and the output terminal that outputs an output of the line driver. a voltage adjustment circuit that adjusts the voltage of the power supply circuit; a first memory that stores a voltage value adjusted by the voltage adjustment circuit; a gain adjuster that adjusts the gain of the input amplifier; a second memory that stores the gain adjusted by the gain adjuster; and a memory control terminal connected to the first memory and the second memory. Including A semiconductor integrated circuit device including The power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate, and an external terminal is provided between the output terminal of the input amplifier and the input terminal of the line driver to connect a filter and to externally set the gain of the line driver. The memory control terminal is a single external terminal among external terminals provided on the semiconductor integrated circuit device that is used to control both the first memory and the second memory and to read and write data from and to the first memory and the second memory. do. [Effects of the Invention]

[0010] According to the semiconductor integrated circuit device of the present disclosure, the input amplifier and line driver are integrated into a monolithic IC, making it difficult for RF noise to be transmitted between elements, eliminating the need for noise-removal filters between elements. Furthermore, since a line driver gain setting circuit is connected to the input terminal of the line driver, or an external terminal is provided so that the line driver gain can be set externally, the line driver can be used in vehicles and capable of driving heavy loads that require high voltage resistance. Furthermore, since the input amplifier and line driver are formed on a single chip, the device can be formed very compactly, and when used as a microphone module, it can be formed in an area approximately half that of conventional devices. As a result, a high-performance, low-cost vehicle microphone can be obtained. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram showing a basic structure of an embodiment (first embodiment) of a semiconductor integrated circuit device according to the present disclosure. [Figure 2] FIG. 10 is a block diagram showing the basic structure of another embodiment (embodiment 2) of the semiconductor integrated circuit device of the present disclosure. [Figure 3]FIG. 10 is a block diagram of another basic structure in the first embodiment. [Figure 4] FIG. 10 is a block diagram of another basic structure in the second embodiment. [Figure 5] FIG. 2 is a block diagram showing a specific example of the configuration of FIG. 1. [Figure 6] FIG. 4 is a block diagram showing a specific example of the configuration of FIG. 3. [Figure 7] FIG. 3 is a block diagram showing a specific example of the configuration of FIG. 2. [Figure 8] FIG. 3 is a block diagram showing another specific example of the configuration of FIG. 2. [Figure 9] FIG. 5 is a block diagram showing a specific example of the configuration of FIG. 4. [Figure 10] 1 is a schematic cross-sectional structural view of an example of a microphone module according to the present disclosure. [Figure 11] 1 is a cross-sectional view showing an example of the structure of a MEMS transducer. [Figure 12] FIG. 1 is a block diagram showing the configuration of a conventional microphone module. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, embodiments of the semiconductor integrated circuit device and microphone module using the same according to the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to these embodiments.

[0013] (Embodiment 1) 1, one embodiment (embodiment 1) of a semiconductor integrated circuit device 1 of the present disclosure includes a power supply circuit 11 for the MEMS transducer 2 connected to the MEMS transducer 2 via an external terminal T1, an input amplifier 12 that receives a signal from the MEMS transducer 2 via an external terminal T2 and amplifies it, and a line driver 13 that amplifies the output of the input amplifier 12 and enables driving of a load connected to an output terminal T3. The power supply circuit 11, the input amplifier 12, and the line driver 13 are integrally formed on a semiconductor substrate (not shown), and a gain setting circuit 14 that determines the gain of the line driver 13 and the DC potential of the output terminal T3 is connected to the input end of the line driver 13. In this case, the gain setting circuit 14 is also integrally formed on the semiconductor substrate.

[0014] That is, the semiconductor integrated circuit device of the first embodiment is a semiconductor integrated circuit device suitable for microphones using MEMS transducers, particularly for in-vehicle microphones. As mentioned above, in-vehicle microphones require in-vehicle components with a withstand voltage of at least 12 V, and a line driver capable of driving a heavy load (driving a low impedance such as 600 Ω) is required. Conventionally, individual amplifiers, power supply circuits, and line drivers are used to achieve a hybrid configuration on a substrate. However, as mentioned above, when a hybrid configuration is performed on a substrate, a path through which RF noise is carried is created in the wiring connecting the individual components. Therefore, measures such as connecting a filter to remove RF noise must be taken. This results in problems such as an increase in the size of the microphone module and an increase in assembly man-hours, resulting in increased costs.

[0015] The semiconductor integrated circuit device 1 of the first embodiment is characterized by incorporating a gain setting circuit 14 that adjusts the gain of the line driver 13 and determines the DC potential of the output terminal T3. As will be described later, the gain setting circuit 14 shown in Fig. 1 is configured so that it can be adjusted externally, thereby providing a one-chip semiconductor integrated circuit device that incorporates the line driver 13, gain setting circuit 14, input amplifier 12, and power supply circuit 11 that correspond to the load connected to the output terminal T3, etc.

[0016] The power supply circuit 11 supplies a bias voltage to the MEMS transducer 2. That is, the operating voltage of the MEMS transducer 2 is, for example, about 12 V, but the power supply voltage supplied to the semiconductor integrated circuit device 1 is about 3.3 V. Therefore, a voltage suitable for the MEMS transducer 2 must be set, and the power supply circuit 11 is a circuit for adjusting the voltage. The output of this power supply circuit 11 is supplied to the MEMS transducer 2 via an external terminal T1.

[0017] The input amplifier 12 amplifies the signal from the MEMS transducer 2 because the signal is very small. The signal from the MEMS transducer 2 is input via an external terminal T2 and amplified. The amplification factor can be adjusted externally by connecting a gain adjustment circuit 15 (see FIG. 3), as in an example described later.

[0018] As mentioned above, the line driver 13 is configured to be able to drive a heavy load connected to this output terminal T3. For example, a normal operational amplifier can be used. The output is adjusted by a gain setting circuit 14 connected to the input terminal of the line driver 13. Although not shown, if the line driver 13 is of a two-wire type, the output is provided by an open-drain output of an FET whose source is connected to ground GND provided on the output terminal side. In the case of a three-wire type, which will be described later, a push-pull output is used.

[0019] The gain setting circuit 14 adjusts the output of the line driver 13 so that it can drive a load connected to its output, and adjusts the desired gain and the DC potential at the output terminal T3 to a desired value. Specifically, as shown in Fig. 7, for example, it is composed of a first resistor R1 connected between the second input terminal 13b of the line driver 13 and ground GND, and a second resistor R2 connected between the second input terminal 13b of the line driver 13 and the output terminal T3. By connecting such resistors R1 and R2, the gain G of the line driver 13 is adjusted.V is G V = R2 / R1, and the DC potential of the output terminal T3 is V dc is V dc =V ref ×(1+R2 / R1). V ref indicates the voltage input to the first input terminal 13a of the line driver 13 at the reference potential (see 10 in FIG. 7). Therefore, by adjusting the first and second resistance values ​​of the first and second resistors R1 and R2, it is possible to match the load to a desired level. In this way, the gain of the line driver can be easily adjusted by the ratio of the first resistance value to the second resistance value, and the DC potential of the output can also be adjusted.

[0020] The MEMS transducer 2 has a structure, an example of which is shown in cross section in Fig. 11. That is, a membrane 21 is disposed on a recess 23 in a semiconductor substrate 22, a backplate 25 is provided via a fixing member 24, and an opening 25a is formed in the backplate 25 to allow sound to pass through. Electrodes 26 and 27 are formed on one end of the membrane 21 and one end of the backplate 25, respectively. With this configuration, when sound S hits the membrane 21, the membrane 21 vibrates, changing the capacitance between it and the backplate 25, and this change in capacitance is detected by the pair of electrodes 26 and 27.

[0021] The output terminal T3 is connected to the power terminal 85 via a load resistor R L The output (OUT) is also formed through an external terminal T6 that is connected to the ground GND. L The extraction of the output (OUT) via is the same in Figures 5 to 7 and 9 described later, but is omitted in each figure. Figures 1 to 4 show an example in which the line driver 13 is of the two-wire type, and the power supply terminal 85 is connected to a phantom power supply.

[0022] In Figure 1, 3 indicates a microphone module in which the semiconductor integrated circuit device 1 and the MEMS transducer 2 are arranged on a substrate (not shown), and 4 indicates the microphone area in which further necessary components are connected to the microphone module 3 and which is covered with a housing.

[0023] (Embodiment 2) In the above-described first embodiment, the gain setting circuit 14 of the line driver 13 is built into the semiconductor integrated circuit device 1. In the second embodiment, the gain setting circuit 14 is not built into the microphone 4, and instead, as described below, the manufacturer of the microphone 4 is able to adjust the output of the line driver 13 during the manufacturing process. This corresponds to cases where the adjustment value differs depending on the characteristics required by each automobile manufacturer that uses the microphone 4. Therefore, the semiconductor integrated circuit device 1 is configured such that an external component A, which includes a filter and can set the gain of the line driver 13, can be disposed outside the semiconductor integrated circuit device 1 so that the gain can be freely adjusted during the manufacturing process of the microphone 4. This external component A can be configured to be immune to the effects of RF noise, for example, by housing the gain setting circuit inside a noise reduction filter, as described below.

[0024] Specifically, as shown in FIG. 2, the output terminal of input amplifier 12 and the input terminal of line driver 13 are formed as external terminals T4 and T5 of semiconductor integrated circuit device 1, respectively, allowing gain setting circuit 14 to be connected externally to semiconductor integrated circuit device 1. By providing such external connection terminals T4 and T5 on semiconductor integrated circuit device 1, the output of line driver 13 can be freely adjusted according to the desired characteristics during the manufacturing process of microphone module 3 or microphone 4. For example, as shown in FIG. 2, external terminals T12 and T13 of microphone module 3 are connected to external terminals T4 and T5 of semiconductor integrated circuit device 1, respectively. External component A, including a filter and a gain setting circuit, is connected between external terminals T12 and T13 and is used to set the gain of the line driver. While external component A is provided externally to microphone module 3 in FIG. 2, it may also be provided inside microphone module 3 and directly connected to external terminals T4 and T5. In this case, the gain of the line driver can be adjusted during the manufacturing process of the microphone module 3, and furthermore, it can be covered with a shield cover (see 31 in Figure 10), and the filter can also be formed inside the microphone module 3. In Figure 2, the same parts as in Figure 1 are given the same reference numerals as in Figure 1, and their explanation will be omitted. [Example]

[0025] Example 1 FIG. 3 shows the basic configuration of FIG. 1 , but with the addition of a gain adjustment circuit 15 for adjusting the gain of the input amplifier 12, a first memory element 16 for storing the voltage value optimally adjusted by the voltage adjustment circuit in the power supply circuit 11, and a second memory element 17 for storing the optimal gain adjusted by the gain adjustment circuit 15. The other components are the same as those in FIG. 1 , and their description is omitted. The addition of the gain adjustment circuit 15 ensures that the amplified output is always constant, regardless of variations in the MEMS transducer 2. Furthermore, by storing the adjusted values ​​of the power supply circuit 11 and the gain adjustment circuit 15 in the first and second memory elements 16 and 17, the device can always operate at the optimal value without the need for adjustment each time it is used. In FIG. 3 , T9 is a memory control terminal that allows the adjustment value to be programmed after the semiconductor integrated circuit device 1 is manufactured. External terminals T10 and T11 can be provided when memory control is performed during the manufacturing stages of the microphone module 3 and the microphone 4.

[0026] This memory control terminal T9 is configured to control both the first memory element 16 and the second memory element 17 with a single terminal. That is, for example, by inputting a predetermined start clock to the memory control terminal T9, the semiconductor integrated circuit device 1 is activated. Then, serial data of a predetermined number of bits (e.g., 8 bits) is input as a predetermined command to notify each memory element of the control of the write or read process for that memory element. Then, in the case of a read operation, a change in the potential of the memory control terminal T9 over a predetermined period (e.g., 8 clocks) is read as data (e.g., 8-bit serial data) indicating the contents of the target memory element. In the case of a write operation, after inputting the data as the command, a desired write value is further input as serial data of a predetermined number of bits (e.g., 8 bits). By providing a common external terminal in this way, the number of external terminals can be reduced, and noise intrusion can be suppressed. The example of providing the gain control circuit 15, the first memory element 16, and the second memory element 17 is not limited to the first embodiment shown in FIG. 1 , but can also be applied to other embodiments and examples. The manufacturer of microphone module 3 stores the adjusted value of power supply circuit 11 in first memory element 16 before shipping the product, thereby enabling accurate adjustment of the bias voltage of the MEMS transducer. The manufacturer of microphone 4 stores the adjusted value of gain adjustment circuit 15 in second memory element 17 before shipping the product, thereby enabling accurate adjustment of the gain of microphone 4 as a whole.

[0027] Example 2 4, in addition to the basic structure of FIG. 2, a gain adjustment circuit 15 that adjusts the gain of the input amplifier 12 is provided, as well as a first memory element 16 that stores a voltage value optimally adjusted by the voltage adjustment circuit in the power supply circuit 11, and a second memory element 17 that stores the optimal gain adjusted by the gain adjustment circuit 15. The other configurations are the same as those of FIG. 2 or 3, and therefore description thereof will be omitted.

[0028] Example 3 5 is a specific example of the circuit shown in FIG. 1. That is, a capacitor C is connected between the output terminal of the input amplifier 12 and the first input terminal 13a of the line driver 13. in and resistor R in A high-pass filter HPF consisting of a MOSFET and a resistor R1 is connected to the line driver 13, and a gain setting circuit 14 is connected between the second input terminal 13b of the line driver 13 and the output terminal T3. That is, the high-pass filter HPF removes DC components and low-frequency noise, and the gain setting circuit 14 adjusts the gain of the line driver 13 and the DC potential at the output terminal T3. This is to enable driving of a load according to the load connected to the output terminal T7. The output terminal T3 is also used as a power supply input terminal and is connected to the connector 5 via the output terminal T7. The power supply V DD supplies power to drive each element in the semiconductor integrated circuit device 1. The power supply V DD is supplied via a ripple elimination device 19. When a first memory element 16 and a second memory element 17 (not shown, see FIG. 3) are added, it is preferable to eliminate noise such as ripples to prevent malfunctions. As the ripple elimination device 19, for example, a regulator circuit that keeps the voltage constant or a ripple filter circuit can be used.

[0029] Although not shown in the examples above, an RF noise filter that removes RF noise is provided between the output terminal T3 and the external terminal T6 of GND. RF and two resistors R RF In the example shown in FIG. 5, a resistor R for an RF noise removal filter is provided inside the microphone module 3 outside the semiconductor integrated circuit device 1. RF and capacitor C RFAs a result, the microphone module 3 has a structure that can remove RF noise of a desired frequency at the manufacturing stage. As shown in the schematic cross-sectional structure of FIG. 10, the microphone module 3 has the semiconductor integrated circuit device 1, the MEMS transducer 2, etc. covered with a shield cover 31. This shield cover 31 is formed with a structure such that a conductor film is formed on one surface of a metal or resin. Therefore, it is possible to form an RF noise removal filter inside this shield cover 31, not inside the semiconductor integrated circuit device 1. In other words, the RF noise removal filter can be formed inside this shield cover 31 without being inside the semiconductor integrated circuit device 1. RF and resistor R RF Specifically, for example, as shown in FIG. RF By forming a resistor 32 that functions as a resistor, it is possible to adjust the cutoff frequency to a desired value. RF A capacitor with a dielectric sandwiched between them can be formed as a resistor or capacitor, or these resistors and capacitors can be formed as chip elements. By using such a configuration, a filter that optimally removes RF noise can be formed.

[0030] The configurations of the ripple elimination device 19, the high-pass filter HPF, the RF noise elimination filter, and the like shown in this example can also be applied to other embodiments and examples as needed.

[0031] Example 4 6 is a specific example of the circuit of FIG. 3, in which an OTP 18 (described later) is provided in place of the first memory element 16 and the second memory element 17 shown in FIG. 3. Specifically, FIG. 6 shows the resistance value of the gain setting circuit 14 in the example of FIG. 5, the input resistance R adjThe microphone 4 is provided with an external terminal T11 so that the above adjustments can be made externally via the OTP 18. That is, a memory control terminal T9 is formed in the semiconductor integrated circuit device 1, and the external terminal T11 is formed in the microphone 4 by connecting to an external terminal T10 of the microphone module 3. As shown in FIG. 8 described later, a capacitor C in and resistor R in If the first and second resistors R1, R2 of the gain setting circuit 14 were provided outside the semiconductor integrated circuit device 1, they could be set to the characteristics desired by, for example, the automobile manufacturer that uses the in-vehicle microphone. However, in this example, they are built into the semiconductor integrated circuit device 1, so an OTP 18 is provided so that they can be adjusted either at the microphone module 3 stage or after it has become the microphone 4. The other configuration is the same as the example shown in FIG. 3 or FIG. 5, and a description thereof will be omitted.

[0032] The OTP 18 not only sets the gain setting circuit 14, but also adjusts the output voltage of the power supply circuit 11 via a voltage adjustment circuit, adjusts the gain of the input amplifier 12 via a gain adjustment circuit (not shown, see 15 in FIG. 3), and adjusts the input of the line driver 13 via a variable input resistor R adj The cutoff frequency of the high-pass filter HPF can be adjusted by adjusting the resistance value of the resistor R, and the output voltage of the reference potential generating circuit 10 can be adjusted from the external terminal T11. The low-pass cutoff frequency fc is obtained by fc=1 / (2πCin·Radj) [Hz]. Note that there is a physical limit to the capacitance value of the capacitor that can be built in, so the input resistor R adj Since a very high resistance is required, it is preferable to use an SCR (switched capacitor resistor).

[0033] The OTP 18 is a memory element such as a one-time programmable ROM, and can be written to only once. Therefore, the adjustment values ​​set in the gain setting circuit 14 are maintained thereafter. The structure including the OTP 18 is not limited to this example, and can be applied to other embodiments and examples. As in this example, by forming an external terminal T11 on the microphone 4, each setting value can be optimized even in the microphone state.

[0034] Example 5 7 shows a specific circuit configuration of the example shown in FIG. 2 of the second embodiment. That is, in this example, the portion corresponding to the external component A in FIG. 2 is composed of a high-pass filter HPF and a gain setting circuit 14, and the high-pass filter HPF is a capacitor C in and resistor R in and are connected in series to remove the DC component and low frequency component from the output of the input amplifier 12.

[0035] Such a capacitor C in and resistor R in The cutoff frequency fc of the high-pass filter HPF in which in ·R in ) [Hz]. Therefore, during the manufacturing stage of the microphone 4, adjustments can be made to remove the desired low frequency components.

[0036] Furthermore, a first resistor R1 is connected between the second input terminal 13b of the line driver 13 and GND, and a second resistor R2 is connected between the second input terminal 13b and the output terminal T3, thereby forming the aforementioned gain setting circuit 14. In this example, the high-pass filter HPF and the gain setting circuit 14 are formed outside the microphone module 3, so that the gain setting circuit 14 can be adjusted in accordance with the load connected to the output terminal T3 during the manufacturing process of the microphone 4. Also, although the high-pass filter HPF and the gain setting circuit 14 are provided outside the microphone module 3 in the example shown in FIG. 7, they can also be provided inside the microphone module 3 and directly connected to the external terminals T4 and T5. In this case, the high-pass filter HPF and the gain setting circuit 14 can be adjusted during the manufacturing process of the microphone module 3, and can be covered with a shield cover (see 31 in FIG. 10), and the RF noise reduction filter can also be formed inside the microphone module 3.

[0037] In the example shown in FIG. 7, the high-pass filter HPF and the gain setting circuit 14 are formed on the substrate of the microphone 4 outside the microphone module 3. Therefore, in order to prevent the gain setting circuit 14 from becoming a risk of noise contamination, the resistor R of the RF noise elimination filter that eliminates the final high frequency noise is RF The capacitor C RF is formed inside the microphone module 3 (in the illustrated example, inside the shield cover 31 (see FIG. 10) of the microphone module 3), and the output terminal T7 has low impedance in the high frequency range. The microphone 4 is structured so that its outer periphery is covered with a housing, and the housing (not shown) is also shielded, so that RF noise does not get mixed in from the outside. Therefore, the resistor R of the RF noise removal filter RF Even if the capacitor C of the RF noise suppression filter is formed outside the microphone module, the final noise suppression characteristics are maintained. RF may also be formed outside the microphone module 3.

[0038] Example 6 Fig. 8 is a modified example of the example of Fig. 7. That is, the example shown in Fig. 7 connects the output of the line driver 13 to the power supply line V DD and the ground line GND, but the example shown in Figure 8 is a three-wire line driver that outputs a signal from the output terminal T15 via the output terminal T14, which is provided as an independent output line in addition to the two wires mentioned above. In a three-wire line driver, as mentioned above, the output is a push-pull output. Although not shown, the push-pull output is generated by, for example, a power supply terminal V DD A PMOS transistor is connected between the output and the output OUT, and an NMOS transistor is connected between the output and ground GND. DD In this case, the output terminals T3 and T7 function as power supply input terminals. In the case of a two-wire system, the load resistance R shown in Figure 1 L (Although omitted in Fig. 7, the power supply terminal 85 is connected to the output terminal T7 in the same way as in Fig. 1, and the load resistance R L The output amplitude is reduced by the voltage drop due to the connection via the line driver 13 (connected via the line driver 13). Which of these is adopted depends on the choice of the automobile manufacturer that uses the in-vehicle microphone. The example in which the line driver 13 is a three-wire type is not limited to the example in FIG. 8, but can be applied to all other embodiments and examples. The same parts as in FIG. 7 are assigned the same reference numerals, and their explanations will be omitted.

[0039] Example 7 The example shown in FIG. 9 is a specific circuit example of FIG. 4, in which the above-mentioned OTP 18 is provided in place of the first memory element 16 and the second memory element 17 shown in FIG. 4. Specifically, FIG. 9 shows a circuit example in which a high-pass filter HPF (capacitor C in and variable resistor R adj) is connected to the outside of the microphone module 3 as shown in FIG. 7, and an external high-pass filter HPF (capacitor C in and resistor R in ) together with the gain setting circuit 14 as an external component in FIG. 4. Since the other configurations are the same as those in FIG. 6 or 7, the same parts are given the same reference numerals and the description thereof will be omitted. In this example, the reference voltage V ref can be adjusted by a program from an external terminal T11.

[0040] The reference voltage V ref This adjustment can be performed during the manufacturing stage of the microphone 4 so as to obtain an optimal midpoint potential in response to variations in the components outside the microphone module 3, such as the high-pass filter HPF and gain setting circuit 14, and to the settings of the gain setting circuit 14. By forming the external terminal T11 on the microphone 4 in this way, it becomes possible to make adjustments so as to obtain desired characteristics even in response to variations in the components outside the microphone module 3, such as the high-pass filter HPF and gain setting circuit 14, or to variations in the housing that forms the outer wall of the microphone. For example, since the housing of most hands-free microphones is made of plastic, variations in the characteristics of the output signal can occur due to deformation, assembly errors, etc.

[0041] As described above, the semiconductor integrated circuit device 1 and the MEMS transducer 2 are mounted on a substrate, and if necessary, a high-pass filter HPF and a gain setting circuit 14 for the line driver 13 are formed. As shown in FIG. 10, a shield cover 31 made of metal or resin with a conductive surface formed on the outer surface is then applied to form the microphone module 3.

[0042] Furthermore, the outer periphery is covered with a housing made of resin or the like, and a connector 5 connected to the output terminal T3 and the external terminal T6 is formed, thereby completing the microphone 4 that can be easily connected to a load.

[0043] (summary) (1) In one aspect of the present disclosure, a semiconductor integrated circuit device that can input a signal from a MEMS transducer includes a power supply circuit for the MEMS transducer, an input amplifier that receives and amplifies the signal from the MEMS transducer, a line driver that amplifies the output of the input amplifier and enables driving of a load connected to the output terminal, and the output terminal that outputs the output of the line driver, wherein the power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate, and a gain setting circuit that determines the gain of the line driver and the DC potential of the output terminal is connected to the input end of the line driver.

[0044] This disclosure integrates a power supply circuit for a MEMS transducer, an input amplifier that receives and amplifies the signal from the MEMS transducer, and a line driver into a single semiconductor chip. Conventionally, the input amplifier and line driver could not be integrated into a single chip because the line driver needed to be adjusted according to the external load connected to the microphone. However, this disclosure incorporates a gain setting circuit that adjusts the gain of the line driver and the DC potential of its output, resulting in a semiconductor integrated circuit device that integrates the input amplifier and line driver into a single chip. As a result, the microphone module can be significantly miniaturized and unnecessary wiring can be eliminated, thereby suppressing external noise. Furthermore, microphone assembly is significantly simplified, significantly reducing the assembly time. This allows for low-noise, high-performance microphones to be sold at very low prices.

[0045] (2) In another aspect of the present disclosure, a semiconductor integrated circuit device that can input a signal from a MEMS transducer includes a power supply circuit for the MEMS transducer, an input amplifier that receives and amplifies the signal from the MEMS transducer, a line driver that amplifies the output of the input amplifier and enables driving of a load connected to the output terminal, and the output terminal that outputs the output of the line driver, wherein the power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate, and an external terminal is provided between the output terminal of the input amplifier and the input terminal of the line driver so that a filter can be connected and the gain of the line driver can be set externally.

[0046] In addition to the same advantage as in (1) above, the present disclosure has an advantage that such external terminals for external connection are formed on the semiconductor integrated circuit device, so that the output of the line driver 13 can be freely adjusted according to the required characteristics in the manufacturing process of the microphone module 3 or the microphone 4. Furthermore, because the configuration allows a filter to be connected, even if a circuit for setting the gain of the line driver is placed outside the semiconductor integrated circuit, the influence of RF noise and the like can be minimized.

[0047] (3) In the semiconductor integrated circuit device to which the signal of the MEMS transducer disclosed in (1) above can be input, it is preferable that a high-pass filter is connected between the output terminal of the input amplifier and the input terminal of the line driver, because this can remove DC components and low-frequency noise.

[0048] (4) In the semiconductor integrated circuit device capable of receiving signals from the MEMS transducer disclosed in (1) to (3) above, it is preferable that the device further comprises a voltage adjustment circuit for adjusting the voltage of the power supply circuit, a first memory for storing the voltage value adjusted by the voltage adjustment circuit, a gain adjuster for adjusting the gain of the input amplifier, and a second memory for storing the gain adjusted by the gain adjuster. This allows manufacturers of microphone modules to accurately adjust the bias voltage of the MEMS transducer, whose characteristics are prone to variations due to manufacturing. Furthermore, manufacturers of in-vehicle microphones can accurately adjust the gain of the input amplifier, taking into account variations due to the various factors mentioned above. Furthermore, by adjusting the resistance value of the variable input resistor constituting the high-pass filter HPF, the output voltage of the reference potential generating circuit, and setting the gain setting circuit, the overall gain of the microphone, taking into account variations, can be accurately adjusted. By storing the adjusted voltage and the adjusted gain of the input amplifier in memory, the gain can be easily set electrically without the need for physical adjustment.

[0049] (5) In the semiconductor integrated circuit device capable of receiving signals from the MEMS transducer disclosed in (4) above, it is preferable that the control data for the first memory and the second memory are input from a common terminal. This is because, while an increase in the number of external terminals makes it easier for external noise to enter, a decrease in the number of external terminals makes it possible to suppress the input of external noise.

[0050] (6) In the semiconductor integrated circuit device capable of receiving a signal from the MEMS transducer disclosed in (4) or (5) above, it is preferable that the device further comprises a power supply input terminal and a ripple eliminator connected between the first memory and the second memory and the power supply input terminal. This makes it possible to eliminate noise from the power supply. This is because noise, such as ripple, in the power supply for the memory in particular can cause malfunction.

[0051] (7) The MEMS microphone module of the present disclosure includes a substrate, a MEMS transducer and a semiconductor integrated circuit device formed on the substrate, and a shielding cover that surrounds the MEMS transducer and the semiconductor integrated circuit device, wherein the semiconductor integrated circuit device is a semiconductor integrated circuit device described in any one of (1) to (6) above.

[0052] This configuration eliminates the need to assemble individual components onto a substrate, making it possible to manufacture a high-performance microphone module very simply and at very low cost. [Explanation of symbols]

[0053] 1. Semiconductor integrated circuit device 2. MEMS Transducers 3 microphone modules 4 microphones 10 Reference potential generation circuit 11 Power circuit 12 Input Amplifier 13 Line Driver 14 Gain setting circuit 15 Gain adjustment circuit 16 First memory element 17 Second memory element 18 One-Time-Pass 19 Ripple removal device 31 Shield cover 32 resistor A. External Components T1, T2, T4, T5, T6, T8, T10, T11, T12, T13 External terminals T3, T7, T14, T15 output terminals T9 Memory control terminal

Claims

1. a power supply circuit for the MEMS transducer; an input amplifier that receives and amplifies a signal from the MEMS transducer; a line driver that amplifies the output of the input amplifier and enables driving of a load connected to an output terminal; the output terminal for outputting the output of the line driver; a voltage regulation circuit that regulates the voltage of the power supply circuit; a first memory that stores a voltage value adjusted by the voltage adjustment circuit; a gain adjuster for adjusting the gain of the input amplifier; a second memory for storing the gain adjusted by the gain adjuster; a memory control terminal connected to the first memory and the second memory; A semiconductor integrated circuit device comprising: the power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate; and a gain setting circuit that determines the gain of the line driver and the DC potential of the output terminal is connected to an input terminal of the line driver; the memory control terminal is a single external terminal, among external terminals provided on the semiconductor integrated circuit device, that is used to control both the first memory and the second memory and to read and write data from and to the first memory and the second memory; A semiconductor integrated circuit device that can input signals from a MEMS transducer.

2. a power supply circuit for the MEMS transducer; an input amplifier that receives and amplifies a signal from the MEMS transducer; a line driver that amplifies the output of the input amplifier and enables driving of a load connected to an output terminal; the output terminal for outputting the output of the line driver; a voltage regulation circuit that regulates the voltage of the power supply circuit; a first memory that stores a voltage value adjusted by the voltage adjustment circuit; a gain adjuster for adjusting the gain of the input amplifier; a second memory for storing the gain adjusted by the gain adjuster; a memory control terminal connected to the first memory and the second memory; A semiconductor integrated circuit device comprising: the power supply circuit, the input amplifier, and the line driver are integrally formed on a semiconductor substrate; and an external terminal is provided between the output terminal of the input amplifier and the input terminal of the line driver so that a filter can be connected and the gain of the line driver can be set externally; the memory control terminal is a single external terminal, among external terminals provided on the semiconductor integrated circuit device, that is used to control both the first memory and the second memory and to read and write data from and to the first memory and the second memory; A semiconductor integrated circuit device that can input signals from a MEMS transducer.

3. 2. The semiconductor integrated circuit device according to claim 1, further comprising a high-pass filter connected between the output terminal of said input amplifier and said input terminal of said line driver.

4. 4. The semiconductor integrated circuit device according to claim 1, further comprising: a power supply input terminal; and a ripple elimination device connected between said first memory and said second memory and said power supply input terminal.

5. a substrate, a MEMS transducer and a semiconductor integrated circuit device formed on the substrate, and a shield cover that covers the periphery of the MEMS transducer and the semiconductor integrated circuit device; A MEMS microphone module comprising: The semiconductor integrated circuit device is a semiconductor integrated circuit device according to any one of claims 1 to 4, the MEMS microphone module further includes an RF noise rejection filter formed of a capacitor and a resistor and connected to the output terminal; The RF noise removal filter is covered by the shield cover. MEMS microphone module.

6. The MEMS microphone module according to claim 5 , wherein the capacitor is formed by sandwiching a dielectric included in the substrate.

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