Temperature sensor and sensor device

Abstract

A temperature sensor (1) comprises a first resistor bridge circuit (11) having a first resistor (R1) and a second resistor (R2) connected in series between an application terminal of a power supply voltage (Vdd) and an application terminal of a ground potential, and a third resistor (R3) and a fourth resistor (R4) connected in series between the application terminal of the power supply voltage and the application terminal of the ground potential, wherein the first resistor is provided on the ground potential side and has a positive temperature characteristic with respect to a resistance value, the second resistor is provided on the power supply voltage side and has a negative temperature characteristic with respect to a resistance value, the third resistor is provided on the power supply voltage side and has a positive temperature characteristic with respect to a resistance value, and the fourth resistor is provided on the ground potential side and has a negative temperature characteristic with respect to a resistance value.

Description

Temperature sensor and sensor device

[0001] The present disclosure relates to temperature sensors.

[0002] Conventionally, a temperature sensor using a constant current source and a diode has been known (see, for example, FIG. 4 of Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2002-368110

[0004] However, when an AD converter is used to convert the output of the temperature sensor into analog digital data, the output of the AD converter is affected by the power supply voltage, which means that the output of the AD converter has the characteristics of the power supply voltage.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a temperature sensor that can prevent the output of an AD converter from having power supply voltage characteristics when AD conversion is performed using the AD converter.

[0006] For example, a temperature sensor according to the present disclosure includes a first resistor bridge circuit having a first resistor and a second resistor connected in series between an application terminal of a power supply voltage and an application terminal of a ground potential, and a third resistor and a fourth resistor connected in series between the application terminal of the power supply voltage and the application terminal of the ground potential, wherein the first resistor is provided on the ground potential side and has a positive temperature characteristic with respect to its resistance value, the second resistor is provided on the power supply voltage side and has a negative temperature characteristic with respect to its resistance value, the third resistor is provided on the power supply voltage side and has a positive temperature characteristic with respect to its resistance value, and the fourth resistor is provided on the ground potential side and has a negative temperature characteristic with respect to its resistance value.

[0007] According to the temperature sensor according to the present disclosure, when AD conversion is performed using an AD converter, it is possible to prevent the output of the AD converter from having power supply voltage characteristics.

[0008] FIG. 1 is a diagram illustrating a configuration of a sensor device according to an exemplary embodiment of the present disclosure. FIG. 2 is a diagram illustrating a specific configuration example of an AD conversion unit according to an embodiment of the present disclosure. FIG. 3 is a timing chart illustrating an example of the behavior of output voltages Vout1 and Vout2 and a comparator output CPout. FIG. 4 is a timing chart illustrating an example of a case where noise is introduced into a temperature sensor according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating a first example of an arrangement of various resistors. FIG. 6 is a diagram illustrating a second example of an arrangement of various resistors. FIG. 7 is a diagram illustrating a third example of an arrangement of various resistors. FIG. 8 is a diagram illustrating a fourth example of an arrangement of various resistors. FIG. 9 is a diagram illustrating a configuration of a sensor device according to a comparative example. FIG. 10 is a diagram illustrating a specific configuration example of an AD conversion unit according to a comparative example. FIG. 11 is a timing chart illustrating an example of the behavior of the output voltage Vout and the comparator output CPout. FIG. 12 is a timing chart illustrating an example of a case where noise is introduced into a temperature sensor according to a comparative example.

[0009] Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[0010] 1. Comparative Example Before describing exemplary embodiments according to the present disclosure, a comparative example will be described for comparison. By describing such a comparative example, the problems will become clear.

[0011] Fig. 9 is a diagram showing the configuration of a sensor device 50 according to a comparative example. The sensor device 50 shown in Fig. 9 includes a temperature sensor 10, an AD conversion unit 20, and a MEMS (Micro Electro Mechanical Systems) sensor 30.

[0012] The temperature sensor 10 includes a constant current source 101 and a diode 102. The constant current source 101 is connected between an application terminal of an internal voltage Vreg and an anode of the diode 102. The cathode of the diode 102 is connected to an application terminal of a ground potential. The anode of the diode 102 is connected to an AD conversion unit 20 via a switch SW10. When a constant current generated by the constant current source 101 flows, the Vf (forward voltage) of the diode 102 changes depending on the temperature. The Vf is AD converted by the AD conversion unit 20, making it possible to detect the temperature.

[0013] The MEMS sensor 30 has a resistor bridge circuit 301 composed of MEMS resistors Ra, Rb, Rc, and Rd. The MEMS resistors Ra and Rb are connected in series between an application terminal of a power supply voltage Vdd and an application terminal of a ground potential. The MEMS resistors Rc and Rd are connected in series between an application terminal of the power supply voltage Vdd and an application terminal of a ground potential.

[0014] The MEMS sensor 30 is configured by integrating a diaphragm and a resistance bridge circuit 301. For example, a silicon substrate is used as the diaphragm, and impurities are diffused on the surface of the silicon substrate to form the resistance bridge circuit 301. The MEMS sensor 30 is a pressure sensor that utilizes the piezoresistance effect. The piezoresistance effect is a phenomenon in which the resistance value changes when pressure is applied to a resistor.

[0015] When pressure is applied to the diaphragm, a change in the resistance value occurs in the MEMS resistors Ra, Rb, Rc, and Rd. A voltage difference occurs between a node Na to which Ra and Rb are connected and a node Nb to which Rc and Rd are connected, depending on the resistance values ​​of the MEMS resistors Ra, Rb, Rc, and Rd. The node Na is connected to the AD conversion unit 20 via a switch SW12, and the node Nb is connected to the AD conversion unit 20 via a switch SW11. The voltage difference is AD converted by the AD conversion unit 20, thereby detecting the pressure.

[0016] When detecting temperature using the temperature sensor 10, the switch SW10 is turned on and the switches SW11 and SW12 are turned off, and when detecting pressure using the MEMS sensor 30, the switch SW10 is turned off and the switches SW11 and SW12 are turned on.

[0017] A DSP (digital signal processor) (not shown) is provided downstream of the AD conversion unit 20. The DSP can correct the pressure value detected by the MEMS sensor 30 based on the temperature detected by the temperature sensor 10. In other words, the temperature characteristics of the resistance value of the resistor bridge circuit 301 are corrected by the temperature sensor 10.

[0018] 10 is a diagram showing a specific configuration example of the AD conversion unit 20. The AD conversion unit 20 includes a non-inverting amplifier circuit 201, an AD converter 202, and a comparator 203.

[0019] The non-inverting amplifier circuit 201 includes an amplifier (op-amp) 201A and resistors 201B and 201C. The non-inverting input terminal of the amplifier 201A is connected to the anode of the diode 102. A switch SW10 (FIG. 9) is connected between the anode of the diode 102 and the non-inverting input terminal of the amplifier 201A. The output terminal of the amplifier 201A is connected to one terminal of a resistor 201B. The other terminal of the resistor 201B and the inverting input terminal of the amplifier 201A are connected to one terminal of a resistor 201C. The other terminal of the resistor 201C is connected to a terminal to which a ground potential is applied. The Vf of the diode 102 is non-invertingly amplified with an amplification factor determined by the resistors 201B and 201C.

[0020] The AD converter 202 is provided in a subsequent stage of the non-inverting amplifier circuit 201. The AD converter 202 is configured as an integral type AD converter, and includes an input resistor Ri, an input switch SWi, a discharge resistor Ro, a discharge switch SWo, a capacitor C, and an amplifier 202A.

[0021] One end of the input resistor Ri is connected to the output terminal of the amplifier 201A. The other end of the resistor Ri is connected to one end of the input switch SWi. The other end of the input switch SWi is connected to a first input terminal of the amplifier 202A. One end of the discharge switch SWo is connected to the first input terminal of the amplifier 202A. The other end of the discharge switch SWo is connected to one end of the discharge resistor Ro. The other end of the discharge resistor Ro is connected to an application terminal of the ground potential. A capacitor C is connected between the first input terminal and the output terminal of the amplifier 202A. A second input terminal of the amplifier 202A is connected to an application terminal of the reference voltage Vref.

[0022] The comparator 203 is provided at a subsequent stage of the AD converter 202. A first input terminal of the comparator 203 is connected to the output terminal of the amplifier 202A. A second input terminal of the comparator 203 is connected to the application terminal of the reference voltage Vref.

[0023] Here, the operation of the AD converter 202 and the comparator 203 will be described. First, by turning on the input switch SWi and turning off the discharge switch SWo, an input current Ii flows through the input resistor Ri, charging the capacitor C. At this time, if the charging time is Ti and the voltage of the capacitor C is Vint, then equation (1) holds: Vint = (Ii × Ti) / C = Vref - Vout （Ｔ＝Ｔｉ） (1) However, Vout （Ｔ＝Ｔｉ） is the output voltage of the amplifier 202A after the charging time Ti has elapsed

[0024] 11 is a timing chart showing an example of the behavior of the output voltage Vout and the comparator output CPout output from the comparator 203. As shown in FIG. 11, during the charging time Ti, the output voltage Vout gradually decreases from the reference voltage Vref.

[0025] Next, by turning the input switch SWi off and the discharge switch SWo on, a discharge current Io flows through the discharge resistor Ro, discharging the capacitor C. At this time, if the discharge time required to discharge the charge stored in the capacitor C during the charging time Ti is defined as To, then the following equation (2) is established: To=(C×Vint) / Io (2)

[0026] Substituting equation (1) into equation (2), we get To = (C × Vint) / Io = (Ii × Ti) / Io (3)

[0027] Here, Ii=(Vin-Vref) / Ri and Io=Vref / Ro (where Vin is the output voltage of the non-inverting amplifier circuit 201). If Ri=Ro, then equation (3) becomes To / Ti=(Vin-Vref) / Vref (4).

[0028] 11, the output voltage Vout gradually increases during the discharge time To, and when the discharge time To has elapsed, the output voltage Vout reaches the reference voltage Vref. The comparator 203 compares the output voltage Vout with the reference voltage Vref, so when the discharge time To has elapsed, the comparator output Cpout switches from low level to high level.

[0029] From equation (4), if the charging time Ti is a fixed value, the discharging time To varies depending on the input voltage Vin. The input voltage Vin is a voltage obtained by amplifying the Vf of the diode 102 by the non-inverting amplifier circuit 201. Therefore, Vf, i.e., the temperature, can be detected by counting the discharging time To, which is the time from when the charging time Ti has elapsed to when the level of the comparator output CPout changes. Note that the output voltage Vout indicated by the dashed line in FIG. 11 indicates a case where Vf, i.e., the input voltage Vin, is smaller than the output voltage Vout indicated by the solid line, and the discharging time To is shorter.

[0030] Here, let's assume that the reference voltage Vref = (1 / 2) × Vdd. In this case, equation (4) becomes To / Ti = (Vf × Av - (1 / 2) × Vdd) / ((1 / 2) × Vdd). Here, Av is the amplification factor of the non-inverting amplifier circuit 201. Therefore, if the AD converter 202 is operated based on Vdd, Vf will not be affected by Vdd, and the output (To / Ti) of the AD converter 202 will be affected by Vdd, i.e., the power supply characteristics. Therefore, to avoid being affected by the power supply characteristics, the AD converter 202 must also be operated based on the internal voltage Vreg. In this case, a constant voltage source such as an LDO (Low Dropout) is required to generate Vreg so that Vreg does not fluctuate even when Vdd fluctuates.

[0031] Furthermore, if noise is present in the temperature sensor 10, the following problem occurs. FIG. 12 is a diagram showing an example of a case where noise is present in the temperature sensor 10. Like FIG. 11, FIG. 12 shows the behavior of the output voltage Vout and the comparator output CPout. In FIG. 12, the output voltage Vout shown by the solid line represents a case where there is no noise, and the output voltage Vout shown by the dashed line represents a case where there is noise. When the input voltage Vin increases due to noise, as in the output voltage Vout shown by the dashed line, the discharge time To becomes longer, resulting in an error ΔTo in the discharge time To. Therefore, there is a problem of temperature detection errors occurring.

[0032] 2. Sensor Device of the Present Disclosure In order to solve the above-described problems, an embodiment of the present disclosure is implemented. Fig. 1 is a diagram showing the configuration of a sensor device 5 according to an exemplary embodiment of the present disclosure.

[0033] The sensor device 5 shown in FIG. 1 includes a temperature sensor 1, an AD conversion unit 2, a MEMS sensor 30, and switches SW1, SW2, SW11, and SW12.

[0034] The temperature sensor 1 has a resistor bridge circuit 11 composed of resistors R1, R2, R3, and R4. The resistors R2 and R1 are connected in series between an application terminal for the power supply voltage Vdd and an application terminal for the ground potential. The resistor R2 is provided on the power supply voltage Vdd side, and the resistor R1 is provided on the ground potential side. The resistors R3 and R4 are connected in series between the application terminal for the power supply voltage Vdd and an application terminal for the ground potential. The resistor R3 is provided on the power supply voltage Vdd side, and the resistor R4 is provided on the ground potential side.

[0035] Resistors R1 and R3 have a positive temperature characteristic for their resistance value. The higher the temperature, the greater the resistance value. Resistors R2 and R4 have a negative temperature characteristic for their resistance value. The higher the temperature, the smaller the resistance value.

[0036] A node N1, to which the resistors R2 and R1 are connected, is connected to the AD conversion unit 2 via a switch SW2. A node N2, to which the resistors R3 and R4 are connected, is connected to the AD conversion unit 2 via a switch SW1. The higher the temperature, the larger the voltage difference between the nodes N1 and N2. The AD conversion unit 2 can detect the temperature by AD converting the voltage difference.

[0037] The MEMS sensor 30 has the same configuration as the comparative example ( FIG. 9 ) described above. The node Na is connected to the AD conversion unit 2 via a switch SW12. The node Nb is connected to the AD conversion unit 2 via a switch SW11. The voltage difference generated between the nodes Na and Nb in response to pressure is AD converted by the AD conversion unit 2, thereby detecting the pressure.

[0038] When detecting temperature using the temperature sensor 1, the switches SW1 and SW2 are turned on and the switches SW11 and SW12 are turned off, and when detecting pressure using the MEMS sensor 30, the switches SW1 and SW2 are turned off and the switches SW11 and SW12 are turned on.

[0039] A DSP (not shown) is provided downstream of the AD conversion unit 2. The DSP can correct the pressure value detected by the MEMS sensor 30 based on the temperature detected by the temperature sensor 1.

[0040] 2 is a diagram showing a specific configuration example of the AD conversion unit 2. The AD conversion unit 2 has a first voltage follower 21, a first AD converter 22, a second voltage follower 23, a second AD converter 24, and a comparator 25.

[0041] The voltage of node N1 in the resistor bridge circuit 11 is input to a first voltage follower 21. A switch SW2 (FIG. 1) is connected between node N1 and the first voltage follower 21. The first AD converter 22 is provided in a subsequent stage of the first voltage follower 21 and has a configuration similar to that of the AD converter 202 according to the comparative example (FIG. 10) described above, so a detailed description thereof will be omitted. An input voltage Vin1 output from the first voltage follower 21 is applied to one end of an input resistor Ri in the first AD converter 22.

[0042] The voltage at node N2 in the resistor bridge circuit 11 is input to the second voltage follower 23. A switch SW1 (FIG. 1) is connected between node N2 and the second voltage follower 23. The second AD converter 24 is provided in a subsequent stage of the second voltage follower 23 and has basically the same configuration as the AD converter 202 according to the comparative example (FIG. 10) described above, so a detailed description will be omitted. However, in the second AD converter 24, the application terminal of the power supply voltage Vdd is connected to the discharge resistor Ro. The input voltage Vin2 output from the second voltage follower 23 is applied to one end of the input resistor Ri in the second AD converter 24.

[0043] The comparator 25 is provided in a subsequent stage of the first AD converter 22 and the second AD converter 24. An output voltage Vout1 output from an amplifier 22A in the first AD converter 22 is applied to a first input terminal of the comparator 25. An output voltage Vout2 output from an amplifier 24A in the second AD converter 24 is applied to a second input terminal of the comparator 25. The comparator 25 compares the output voltages Vout1 and Vout2 and outputs the result as a comparator output CPout.

[0044] In the first AD converter 22, by turning the input switch SWi on and the discharge switch SWo off, an input current Ii flows through the input resistor Ri, thereby charging the capacitor C. Thereafter, by turning the input switch SWi off and the discharge switch SWo on, a discharge current Io flows through the discharge resistor Ro, thereby discharging the capacitor C. At this time, as shown in FIG. 2 , the input current Ii flows to the amplifier 22A side, and the discharge current Io flows to the ground potential side.

[0045] 3 is a timing chart showing an example of the behavior of the output voltages Vout1 and Vout2 and the comparator output CPout. The output voltage Vout1 drops from the reference voltage Vref during the charging time Ti and rises to the reference voltage Vref during the discharging time To.

[0046] Here, since Vref = (1 / 2) × Vdd, from equation (4), To / Ti = (Vin1 - Vref) / Vref = ((Vdd × R1) / (R1 + R2) - (1 / 2) × Vdd) / ((1 / 2) × Vdd) (5)

[0047] It can be seen from equation (5) that Vdd can be canceled, and therefore the influence of Vdd on the output of the first AD converter 22 can be suppressed.

[0048] In the second AD converter 24, by turning the input switch SWi on and the discharge switch SWo off, an input current Ii flows through the input resistor Ri, charging the capacitor C. Thereafter, by turning the input switch SWi off and the discharge switch SWo on, a discharge current Io flows through the discharge resistor Ro, discharging the capacitor C. At this time, as shown in FIG. 2 , the input current Ii flows to the second voltage follower 23 side, and the discharge current Io flows to the amplifier 24A side.

[0049] 3, the output voltage Vout2 rises from the reference voltage Vref during the charging time Ti and drops to the reference voltage Vref during the discharging time To. The influence of Vdd on the output of the second AD converter 24 can also be suppressed.

[0050] 3, when the discharge time To has elapsed, the magnitudes of the output voltages Vout1 and Vout2 are reversed, and the comparator output CPout switches from low to high. By counting the time (discharge time To) from the time when the fixed charge time Ti has elapsed until the level of the comparator output CPout switches, the input voltages Vin1 and Vin2, and therefore the temperature, can be detected.

[0051] FIG. 4 is a diagram illustrating an example of a case where noise is present in the temperature sensor 1. Similar to FIG. 3, FIG. 4 illustrates the behavior of the output voltages Vout1 and Vout2 and the comparator output CPout. In FIG. 4, the solid line indicates the output voltage Vout when there is no noise, while the dashed line indicates the output voltage Vout when there is noise. The noise is common-mode noise (such as PSRR) that affects the nodes N1 and N2 in the same phase. As a result, even when noise is present, the output voltages Vout1 and Vout2 deviate in the same direction, as shown by the dashed lines in FIG. 4, and thus the error in the discharge time To is suppressed. Thus, the configuration of the temperature sensor 1 and AD conversion unit 2 according to the present disclosure improves noise resistance.

[0052] The node Na in the MEMS sensor 30 is connected to the first voltage follower 21 via the switch SW12, and the node Nb in the MEMS sensor 30 is connected to the second voltage follower 23 via the switch SW11. As a result, similar to the case of temperature detection, pressure can be detected by measuring the discharge time To. Even if noise is introduced into the MEMS sensor 30, noise resistance is improved similar to the case of temperature detection. In other words, since the temperature sensor 1 has the same circuit configuration as the MEMS sensor 30, it is possible to increase affinity with the MEMS sensor 30.

[0053] 3. First Example of Resistor Arrangement Various examples of arrangements of the resistors R1 to R4 in the temperature sensor 1 and the MEMS resistors Ra to Rd in the MEMS sensor 30 will be described below.

[0054] Fig. 5 is a diagram showing a first arrangement example of resistors R1 to R4 and MEMS resistors Ra to Rd. In the configuration shown in Fig. 5, a sensor device 5 has a MEMS chip 3 and an ASIC (application specific integrated circuit) chip 4. This also applies to the configurations shown in Figs. 6 to 8, which will be described later.

[0055] 5, the resistors R1 to R4 and the MEMS resistors Ra to Rd are integrated into the MEMS chip 3. A diaphragm is also integrated into the MEMS chip 3. With this configuration, the MEMS chip 3 is provided with a pad P31 for applying a power supply voltage Vdd connected to the resistors R2 and R3, a pad P32 connected to the node N2, a pad P33 connected to the node N1, and a pad P34 for applying a ground potential connected to the resistors R1 and R4.

[0056] Furthermore, the MEMS chip 3 is provided with a pad P35 for applying a power supply voltage Vdd connected to the resistors Ra and Rc, a pad P36 connected to the node Nb, a pad P37 connected to the node Na, and a pad P38 for applying a ground potential connected to the resistors Rb and Rd.

[0057] The ASIC chip 4 is provided with pads P41 to P48 which are connected to the pads P31 to P38 by wires Wr, respectively.

[0058] The ASIC chip 4 is also provided with AD converters 22 and 24 and a DSP 400. This also applies to the configurations shown in Figures 6 to 8, which will be described later.

[0059] In this way, since the temperature detection resistors R1 to R4 are provided on the MEMS chip 3, the temperature of the MEMS chip 3 can be measured directly, and the cause of error with the temperature of the MEMS sensor 30 is reduced.

[0060] 6 is a diagram showing a second example of the arrangement of resistors R1 to R4 and MEMS resistors Ra to Rd. In the configuration shown in FIG. 6, resistors R1 to R4 are provided on the ASIC chip 4. As a result, the MEMS chip 3 is provided with a pad P31 for applying a power supply voltage Vdd connected to resistors Ra and Rc, a pad P32 connected to node Nb, a pad P33 connected to node Na, and a pad P34 for applying a ground potential connected to resistors Rb and Rd. The ASIC chip 4 is provided with pads P41 to P44 connected to pads P31 to P34, respectively, by wires Wr.

[0061] This configuration allows the number of pads and wires to be reduced. Also, by providing the resistors R1 to R4 having predetermined temperature characteristics on the ASIC chip 4, which is separate from the MEMS chip 3, the resistors R1 to R4 can be easily formed.

[0062] 7 is a diagram showing a third example of the arrangement of the resistors R1 to R4 and the MEMS resistors Ra to Rd. In the configuration shown in Fig. 7, the resistors R3 and R1 are provided on the MEMS chip 3, and the resistors R2 and R4 are provided on the ASIC chip 4.

[0063] A pad P31 for applying a power supply voltage Vdd, which is connected to the resistors Ra and Rc, a pad P32 connected to a node Nb, a pad P33 connected to a node Na, and a pad P34 for applying a ground potential, which is connected to the resistors Rb and Rd, are provided on the MEMS chip 3. One end of the resistor R3 is connected to the pad P31. A pad P35 connected to the other end of the resistor R3 is provided on the MEMS chip 3. A pad P36 connected to one end of the resistor R1 and a pad P37 connected to the other end of the resistor R1 are provided on the MEMS chip 3.

[0064] The ASIC chip 4 is provided with pads P41 to P47, which are connected to the pads P31 to P37 by wires Wr, respectively. The ASIC chip 4 is provided with a switch SW41 having one end connected to the pad P44. The other end of the switch SW41 is connected to a terminal to which the ground potential is applied. One end of a resistor R2 is connected to the pad P41. The other end of the resistor R2 is connected to the pad P46. One end of a resistor R4 is connected to the pad P45. The ASIC chip 4 is provided with a switch SW42 having one end connected to the other end of the resistor R4 and the pad P47. The other end of the switch SW42 is connected to a terminal to which the ground potential is applied.

[0065] When detecting pressure using the MEMS sensor 30, the switch SW41 is turned on and the switch SW42 is turned off. When detecting temperature using the temperature sensor 1, the switch SW41 is turned off and the switch SW42 is turned on.

[0066] In this way, resistors R1 and R3, both of which have a positive temperature characteristic with respect to their resistance value, are provided on the MEMS chip 3, and resistors R2 and R4, both of which have a negative temperature characteristic with respect to their resistance value, are provided on the ASIC chip 4. Resistors R1 and R3 can be formed as resistors having the same resistance, i.e., the same temperature characteristic, as resistors Ra to Rd in the MEMS sensor 30. Furthermore, resistors R2 and R4, which have the opposite temperature characteristic to resistors R1 and R3, can be formed on the ASIC chip 4. This makes it easier to form resistors R1 to R4. Furthermore, providing resistors R1 and R3 on the MEMS chip 3 reduces the error factor with respect to the temperature of the MEMS sensor 30. Furthermore, the number of pads and wires can be reduced.

[0067] The resistors R2 and R4 may be provided on the MEMS chip 3, and the resistors R1 and R3 may be provided on the ASIC chip 4.

[0068] 6. Fourth Example of Resistor Arrangement FIG. 8 is a diagram showing a fourth example of arrangement of resistors R1 to R4 and MEMS resistors Ra to Rd. The difference between the configuration shown in FIG. 8 and the previously described third example of arrangement (FIG. 7) is that a switch SW31 having one end connected to resistors Rb and Rd is provided on the MEMS chip 3. The other end of the switch SW31 and the resistor R3 are connected to pad P34. Pad P44, which is connected to pad P34 by wire Wr, is connected to switch SW41 and resistor R4. One end of resistor R1 is connected to pad P35. Pad P45, which is connected to pad P35 by wire Wr, is connected to resistor R2. The other end of resistor R1 is connected to pad P36. Pad P46, which is connected to pad P36 by wire Wr, is connected to switch SW42.

[0069] When detecting pressure using the MEMS sensor 30, the switches SW31 and SW41 are turned on and the switch SW42 is turned off. When detecting temperature using the temperature sensor 1, the switches SW31 and SW41 are turned off and the switch SW42 is turned on.

[0070] In this way, compared to the configuration shown in FIG. 7, by providing switch SW31, the pads connected to resistors Rb and Rd and the pad connected to resistor R3 can be shared, thereby further reducing the number of pads and wires.

[0071] 7. Others Although exemplary embodiments have been described above, the embodiments can be modified in various ways within the scope of the spirit of the present invention.

[0072] 8. Supplementary Notes As described above, for example, a temperature sensor (1) according to one aspect of the present disclosure includes a first resistor bridge circuit (11) having a first resistor (R1) and a second resistor (R2) connected in series between an application terminal of a power supply voltage (Vdd) and an application terminal of a ground potential, and a third resistor (R3) and a fourth resistor (R4) connected in series between the application terminal of the power supply voltage and the application terminal of the ground potential, wherein the first resistor is provided on the ground potential side and has a positive temperature characteristic with respect to its resistance value, the second resistor is provided on the power supply voltage side and has a negative temperature characteristic with respect to its resistance value, the third resistor is provided on the power supply voltage side and has a positive temperature characteristic with respect to its resistance value, and the fourth resistor is provided on the ground potential side and has a negative temperature characteristic with respect to its resistance value (first configuration, FIG. 1 ).

[0073] Furthermore, a sensor device (5) according to one aspect of the present disclosure includes the temperature sensor (1) of the first configuration described above and an AD conversion unit (2) provided downstream of the resistor bridge circuit (11), wherein the AD conversion unit includes: a first AD converter (22) connectable to a first node (N1) at which the first resistor and the second resistor are connected; and a second AD converter (24) connectable to a second node (N2) at which the third resistor and the fourth resistor are connected; wherein the first AD converter and the second AD converter each include an amplifier (22A, 24A) having a first input terminal to which a reference voltage (Vref) can be applied, and a capacitor (C) connected between the second input terminal of the amplifier and the output terminal of the amplifier; and wherein the first AD converter and the second AD converter are configured to perform AD conversion by charging and discharging the capacitor based on the voltage of the first node or the voltage of the second node (second configuration, FIG. 2).

[0074] In the second configuration, the reference voltage (Vref) may be a voltage based on the power supply voltage (Vdd), and in the first AD converter (22), the capacitor is discharged by a discharge current (Io) flowing to the ground potential side, and in the second AD converter (24), the capacitor is discharged by a discharge current (Io) flowing from the power supply voltage side (third configuration, FIG. 2).

[0075] Furthermore, the second or third configuration may be configured to include a comparator (25) configured to receive the output of the amplifier (22A) in the first AD converter (22) and the output of the amplifier (24A) in the second AD converter (24) (fourth configuration, FIG. 2).

[0076] Furthermore, in any of the second to fourth configurations, the sensor may further include a MEMS sensor (30) having a second resistor bridge circuit (301) including a first MEMS resistor (Ra) and a second MEMS resistor (Rb) connected in series between the power supply voltage (Vdd) application terminal and the ground potential application terminal, and a third MEMS resistor (Rc) and a fourth MEMS resistor (Rd) connected in series between the power supply voltage application terminal and the ground potential application terminal, wherein a third node (Na) connecting the first MEMS resistor and the second MEMS resistor is connectable to the first AD converter (22), and a fourth node (Nb) connecting the third MEMS resistor and the fourth MEMS resistor is connectable to the second AD converter (24) (fifth configuration, FIG. 1).

[0077] In addition, the fifth configuration may be configured to include a first chip (3) on which the first to fourth resistors (R1 to R4) and the first to fourth MEMS resistors (Ra to Rd) are provided (sixth configuration, Figure 5).

[0078] In addition, the fifth configuration may also be configured to include a first chip (3) on which the first to fourth MEMS resistors (Ra to Rd) are provided, and a second chip (4) on which the first to fourth resistors (R1 to R4) are provided (seventh configuration, Figure 6).

[0079] Furthermore, in the fifth configuration, the fifth configuration may include a first chip (3) on which the first to fourth MEMS resistors (Ra to Rd) are provided, and a second chip (4), wherein the first resistor (R1) and the third resistor (R3) are provided on the first chip, and the second resistor (R2) and the fourth resistor (R4) are provided on the second chip, or the second resistor and the fourth resistor are provided on the first chip, and the first resistor and the third resistor are provided on the second chip (eighth configuration, Figures 7 and 8).

[0080] In addition, in the above-mentioned eighth configuration, a first switch (SW41) connected between the second MEMS resistor (Rb) and the fourth MEMS resistor (Rd) and the application terminal of the ground potential, and a second switch (SW42) connected between the first resistor (R1) and the fourth resistor (R4) and the application terminal of the ground potential may be provided on the second chip (4) (ninth configuration, Figures 7 and 8).

[0081] In addition, in the above-mentioned ninth configuration, a pad (P34) to which the third resistor (R3) or the second resistor (R2) is connected, and a third switch (SW31) connected between the second MEMS resistor (Rb) and the fourth MEMS resistor (Rd) and the pad may be provided on the first chip (3) (tenth configuration, Figure 8).

[0082] The present disclosure can be used, for example, for temperature compensation of MEMS sensors.

[0083] REFERENCE SIGNS LIST 1 Temperature sensor 2 AD conversion unit 3 MEMS chip 4 ASIC chip 5 Sensor device 10 Temperature sensor 11 Resistance bridge circuit 20 AD conversion unit 21 First voltage follower 22 First AD converter 22A Amplifier 23 Second voltage follower 24 Second AD converter 24A Amplifier 25 Comparator 30 MEMS sensor 50 Sensor device 101 Constant current source 102 Diode 301 Resistance bridge circuit C Capacitor P31 to P38 Pads P41 to P48 Pads R1, R2, R3, R4 Resistors Ra, Rb, Rc, Rd MEMS resistors Ri Input resistor Ro Discharge resistor SW1, SW2, SW11, SW12 Switches SW31 Switch SW41 Switch SW42 Switch SWi Input switch SWo Discharge switch Wr Wire

Claims

1. a first resistor bridge circuit including a first resistor and a second resistor connected in series between an application end of a power supply voltage and an application end of a ground potential, and a third resistor and a fourth resistor connected in series between the application end of the power supply voltage and the application end of the ground potential, the first resistor is provided on the ground potential side and has a positive temperature characteristic with respect to a resistance value; the second resistor is provided on the power supply voltage side and has a negative temperature characteristic with respect to a resistance value; the third resistor is provided on the power supply voltage side and has a positive temperature characteristic with respect to a resistance value; The fourth resistor is provided on the ground potential side, and has a negative temperature characteristic with respect to a resistance value.

2. A temperature sensor comprising: the temperature sensor according to claim 1; and an AD conversion unit provided in a subsequent stage of the resistor bridge circuit; The AD conversion unit includes: a first AD converter connectable to a first node to which the first resistor and the second resistor are connected; a second AD converter connectable to a second node to which the third resistor and the fourth resistor are connected; having each of the first AD converter and the second AD converter includes an amplifier having a first input terminal to which a reference voltage can be applied, and a capacitor connected between a second input terminal of the amplifier and an output terminal of the amplifier; A sensor device, wherein the first AD converter and the second AD converter are configured to perform AD conversion by charging the capacitor based on a voltage of the first node or a voltage of the second node, and discharging the capacitor, respectively.

3. the reference voltage is a voltage based on the power supply voltage, In the first AD converter, a discharge current flows to a ground potential side, thereby discharging the capacitor.

3. The sensor device according to claim 2, wherein in the second AD converter, a discharge current flows from the power supply voltage side to discharge the capacitor.

4. The sensor device according to claim 2 , further comprising a comparator configured to receive an output of the amplifier in the first AD converter and an output of the amplifier in the second AD converter.

5. a MEMS sensor having a second resistor bridge circuit including a first MEMS resistor and a second MEMS resistor connected in series between an application end of the power supply voltage and an application end of the ground potential, and a third MEMS resistor and a fourth MEMS resistor connected in series between the application end of the power supply voltage and the application end of the ground potential, a third node to which the first MEMS resistor and the second MEMS resistor are connected is connectable to the first AD converter; The sensor device according to claim 2 , wherein a fourth node to which the third MEMS resistor and the fourth MEMS resistor are connected is connectable to the second AD converter.

6. The sensor device according to claim 5 , further comprising a first chip on which the first to fourth resistors and the first to fourth MEMS resistors are provided.

7. 6. The sensor device according to claim 5, comprising: a first chip on which the first to fourth MEMS resistors are provided; and a second chip on which the first to fourth resistors are provided.

8. a first chip on which the first to fourth MEMS resistors are provided, and a second chip; 6. The sensor device of claim 5, wherein the first resistor and the third resistor are provided on the first chip, and the second resistor and the fourth resistor are provided on the second chip, or the second resistor and the fourth resistor are provided on the first chip, and the first resistor and the third resistor are provided on the second chip.

9. 9. The sensor device according to claim 8, wherein a first switch connected between the second MEMS resistor and the fourth MEMS resistor and an application terminal of the ground potential, and a second switch connected between the first resistor and the fourth resistor and an application terminal of the ground potential are provided on the second chip.

10. The sensor device according to claim 9 , wherein a pad to which the third resistor or the second resistor is connected, and a third switch connected between the second MEMS resistor and the pad and between the fourth MEMS resistor and the pad are provided on the first chip.