JP2013124879A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor device capable of preventing destruction caused by ESD and achieving high accuracy.SOLUTION: The sensor device includes a sensor element 1 having a sensor part 11 for generating an output voltage according to the physical amount of a detection target and a first ESD protection circuit 12, and an IC element 2 having a signal processing circuit 21 for signal-processing the output voltage of the sensor part 11 and a second ESD protection circuit 22. The sensor device includes offset cancel means 3 for canceling an offset voltage determined by a leakage current Iflowing through the first ESD protection circuit 12 and the ESD protection circuit 22 and impedance of the sensor part 11.

Description

  The present invention relates to a sensor device.

  Conventionally, an infrared sensor module including an infrared sensor, an IC element that processes an output signal of the infrared sensor, and a package that houses the infrared sensor and the IC element has been proposed (for example, Patent Document 1). The infrared sensor described in Patent Document 1 is an infrared array sensor formed using a micromachining technique. In this infrared sensor, a plurality of pixel units each including a thermal infrared detection unit and a MOS transistor which is a pixel selection switching element are arranged in a two-dimensional array on one surface side of a base substrate made of a silicon substrate. Yes. Patent Document 1 describes that the temperature sensing part of the thermal infrared detection part can be constituted by a thermopile, a resistance bolometer, a pyroelectric thin film, or the like. Note that Patent Document 1 describes that an infrared sensor is not limited to an infrared array sensor, and may have at least one temperature sensing unit. Patent Document 1 describes that a bare chip is used as an IC element.

In addition, in a semiconductor device such as an IC, an ESD protection circuit is generally provided on a chip in order to prevent the destruction of the device due to electrostatic discharge (ESD) (for example, non-patent). Reference 1). Non-Patent Document 1 describes, as an ESD protection circuit, a series circuit of _two diodes D ₁ and D ₂ connected between a ground line and a power supply voltage line V _DD as shown in FIG. .

JP 2011-174762 A

“Analog CMOS Integrated Circuit Design and Application”, Maruzen Co., Ltd., October 10, 2003, 4th edition, p. 804-807

  In a sensor device including a sensor element and an IC element that performs signal processing on the output voltage of the sensor element, the amplitude of the output voltage of the sensor element is small and the output impedance of the sensor element is high. Processing is often performed. For example, in the above-described infrared sensor module, the amplitude of the output voltage of the infrared sensor, which is a sensor element, is small, and the output impedance of the infrared sensor is high. It is conceivable to provide an A / D conversion circuit for analog-digital conversion of the analog output voltage.

  By the way, in the sensor device such as the above-described infrared sensor module, the present inventors provide an ESD protection circuit for each of the infrared sensor and the IC element in order to prevent the infrared sensor and the IC element from being damaged by ESD. I thought.

  However, in a sensor device in which an ESD protection circuit is provided for each of an infrared sensor and an IC element as sensor elements, an offset voltage is generated due to a leakage current flowing through each ESD protection circuit, and the S / N ratio is lowered. There was a thing.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a sensor device capable of preventing breakage due to ESD and achieving high accuracy. .

  A sensor device according to the present invention includes a sensor unit that generates an analog output voltage corresponding to a physical quantity to be detected and a first ESD protection circuit, a signal processing circuit that performs signal processing on the output voltage, and a second A sensor device including an IC element having an ESD protection circuit, wherein a leakage current flowing in the sensor unit due to the first ESD protection circuit and the second ESD protection circuit, and an impedance of the sensor unit, And an offset canceling means for canceling the offset voltage determined by.

  In the sensor device, the first ESD protection circuit includes a first diode connected between the output terminal on the high potential side of the sensor element and the first power supply voltage line with the output terminal side as an anode side. And a second diode connected between the output end of the sensor element and the first ground line with the output end side as a cathode side, and the second ESD protection circuit includes the sensor element A third diode connected between the input terminal of the IC element connected to the output terminal and the second power supply voltage line with the input terminal side as the anode side, the input terminal and the second ground A fourth diode is preferably connected to the line with the input end side as the cathode side.

  In the sensor device, the offset canceling unit includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or the input terminal. A series circuit of a second analog switch and a leakage current detection resistor provided between the second ground line, and the first analog switch and the second analog switch provided in the IC element are controlled. A control unit having a function of performing the first input voltage in a state in which the first analog switch is turned off and the second analog switch is turned on by the control unit according to a resistance value of the leak current detection resistor A first calculation unit that obtains a leakage current value by dividing the first analog switch and the second analog switch by the control unit. Gusuitchi it is preferable to provide a second arithmetic unit for determining a value obtained by subtracting the product of the second input voltage in a state of being turned off and the leakage current value impedance.

  In the sensor device, the offset canceling unit includes an analog switch provided between the sensor unit and the output end, and between the output end and the first ground line or between the input end and the second end. A leakage current detecting resistor provided between the ground line, a control unit provided in the IC element and having a function of controlling the analog switch, and the analog switch being turned off by the control unit. A first calculation unit that obtains a leakage current value by dividing the first input voltage by the resistance value of the resistor, and a second input voltage in a state where the first analog switch is turned on by the control unit It is preferable to include a second calculation unit that obtains a value obtained by subtracting the product of the leakage current value and the impedance.

  In the sensor device, the offset canceling unit includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or the input terminal. A series circuit of a second analog switch and a leakage current detection resistor provided between the second ground line, the first power supply voltage line and the output terminal, or the second power supply voltage A series circuit of a current source and a third analog switch provided between a line and the input terminal, and the first analog switch, the second analog switch, and the third analog switch provided in the IC element A control unit having a function of controlling a switch, and the control unit turns off the first analog switch and turns on the second analog switch; The resistance value of the leakage current detection resistor is obtained by dividing the first input voltage when the third analog switch is turned on by the current value of the current source, and the controller controls the first input voltage. Preliminary calculation for obtaining the impedance by dividing the second input voltage by the current value of the current source when the analog switch is on, the second analog switch is off, and the third analog switch is on. And the controller calculates the third input voltage when the first analog switch is off, the second analog switch is on, and the third analog switch is off. A first calculation unit that obtains a leakage current value by dividing by a resistance value of the leakage current detection resistor, and the control unit turns on the first analog switch. Further, a value obtained by subtracting the product of the leakage current value and the impedance obtained by the preliminary calculation unit from the fourth input voltage in a state where the second analog switch is off and the third analog switch is off. It is preferable to provide the 2nd calculating part which calculates | requires.

  In the sensor device, the offset canceling unit includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or the input terminal. A series circuit of a second analog switch and a leakage current detection resistor provided between the second ground line and a variable current source provided between the first power supply voltage line and the output terminal And a third analog switch series circuit and a control unit provided in the IC element and having a function of controlling the first analog switch, the second analog switch, the third analog switch, and the variable current source And the control unit turns on the first analog switch, turns off the second analog switch, and turns off the third analog switch. The difference between the first input voltage when the variable current source is controlled to the first current value and the second input voltage when the variable current source is controlled to the second current value Is divided by the difference between the first current value and the second current value to obtain the impedance of the sensor unit, and the control unit turns off the first analog switch and the second analog switch. And the third analog switch is on and the variable current source is controlled to the third current value, the third input voltage is divided by the third current value to thereby reduce the leakage current. A preliminary calculation unit for obtaining a resistance value of the detection resistor; and a fourth in a state where the first analog switch is turned off, the second analog switch is turned on, and the third analog switch is turned off by the control unit. The input voltage of the A first calculation unit for obtaining a leakage current value by dividing by a resistance value of the leakage current detection resistor obtained by the preparation calculation unit, and the control unit turns on the first analog switch and the second analog switch. A second computing unit for obtaining a value obtained by subtracting a product of the leakage current value and the impedance obtained by the preliminary computing unit from a fifth input voltage in a state in which the third analog switch is turned off; It is preferable to provide.

  In this sensor device, the sensor element includes a plurality of sensor units, and the offset canceling unit is provided in the sensor element and has the same configuration as the sensor unit, and the dummy sensor Provided in the IC element, a first analog switch provided between the sensor unit and the output terminal, a plurality of second analog switches provided between the sensor unit and the output terminal, respectively. A control unit having a function of controlling the first analog switch and each of the second analog switches, and a state in which the first analog switch is turned off and one of the second analog switches is turned on by the control unit. In the state where the first analog switch is turned on and the one second analog switch is turned on from the first input voltage at A first operation unit that obtains the offset voltage by multiplying a value obtained by subtracting the second input voltage by 2; and a second operation unit that obtains a value obtained by subtracting the offset voltage from the first input voltage. Is preferred.

  In this sensor device, the sensor element includes a plurality of sensor units, and a plurality of analog switches provided between each of the sensor units and the output terminal, and the offset canceling unit includes: A control unit provided in the IC element and having a function of controlling each analog switch, and a state in which one of the first analog switches is turned on and the other one of the first analog switches is turned off by the control unit 2 is multiplied by the difference between the first input voltage and the second input voltage in a state where the one first analog switch is on and the other one first analog switch is off. A first computing unit that obtains the offset voltage and a second computing unit that obtains a value obtained by subtracting the offset voltage from the second input voltage. Masui.

  In this sensor device, the sensor element includes a plurality of sensor units, and a plurality of analog switches provided between each of the sensor units and the output terminal, and the offset canceling unit includes: A control unit provided in the IC element and having a function of controlling each analog switch, and one of the two analog switches randomly selected by the control unit is on and the other is off. The average value obtained by accumulating the second input voltage in a state where both of the two analog switches randomly selected by the control unit are turned on and dividing by the number of accumulations is subtracted from the input voltage of 1. A first calculation unit that calculates the offset voltage by multiplying the value by 2; and a second calculation unit that calculates a value obtained by subtracting the offset voltage from the first input voltage Preferably comprises a.

  In the sensor device, the offset canceling unit includes a dummy sensor unit provided in the sensor element and having the same configuration as the sensor unit and connected in reverse parallel to the sensor unit, the dummy sensor unit, and the output terminal. From the first input voltage in a state where the analog switch is turned off by the control unit, and a control unit that is provided in the IC element and has a function of controlling the analog switch. Preferably, the control unit includes a calculation unit that obtains a value obtained by subtracting a value obtained by multiplying the second input voltage by 2 when the first analog switch is turned on.

  In the sensor device, the offset canceling unit includes a first analog switch provided between the sensor unit and the output terminal, and a first analog switch provided between the output terminal and the first ground line. A third circuit connected in parallel to a series circuit of one dummy sensor section, a second analog switch, and a second dummy sensor section; and a series circuit of the second analog switch and the second dummy sensor section. An analog switch; a control unit provided in the IC element and having a function of controlling the first analog switch, the second analog switch, and the second analog switch; and the control unit configured to control the first analog switch. The first input voltage in the state where the second analog switch is turned on and the third analog switch is turned off is divided by 2 A first calculation unit for obtaining an offset voltage, and a second state in which the first analog switch is turned on, the second analog switch is turned off, and the third analog switch is turned off by the control unit. A second calculation unit that obtains a value obtained by subtracting the offset voltage from the input voltage, and each of the first dummy sensor unit and the second dummy sensor unit is provided in the sensor element and includes the sensor unit. It is preferable that the first dummy sensor unit and the second dummy sensor unit have the same configuration and are connected in reverse series.

  In the sensor device of the present invention, it is possible to prevent destruction due to ESD and to achieve high accuracy.

(A) is a schematic circuit diagram of the sensor apparatus of Embodiment 1, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 1. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 2, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 2. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 3, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 3. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 4, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 4. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 5, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 5. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 6, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 6. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 7, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 7. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 8, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 8. (A) is a schematic circuit diagram of the sensor apparatus of Embodiment 9, (b) is a schematic equivalent circuit diagram of the sensor apparatus of Embodiment 9. It is explanatory drawing of the conventional ESD protection circuit.

(Embodiment 1)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG.

  The sensor device includes a sensor unit 1 having a sensor unit 11 that generates an output voltage corresponding to a physical quantity to be detected and a first ESD protection circuit 12, a signal processing circuit 21 that performs signal processing on the output voltage of the sensor unit 11, and a first one. IC element 2 having two ESD protection circuits 22. 1A is a schematic circuit diagram of the sensor device, and FIG. 1B is an equivalent circuit diagram of the sensor device. Here, in FIG. 1B, the equivalent circuit of the sensor unit 11 is represented by a series circuit of a voltage source Vs corresponding to the signal voltage of the output voltage of the sensor unit 11 and a resistor Rs corresponding to the impedance of the sensor unit 11. It is. In short, the voltage of the voltage source Vs is the signal voltage of the sensor unit 11, and the resistance value of the resistor Rs is the impedance of the sensor unit 11.

Further, the sensor device, the offset canceling to cancel the offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Means 3 are provided.

The first ESD protection circuit 12 includes a first diode D ₁ connected between the output terminal on the high potential side of the sensor element 1 and the first power supply voltage line V _DD1 with the output terminal side as the anode side, It comprises a second diode D ₂ connected between the output end of the sensor element 1 and the first ground line V _GND1 with the output end side as the cathode side. Therefore, the first ESD protection circuit 12 can have a simple circuit configuration including a series circuit of _two diodes D ₁ and D ₂ .

The second ESD protection circuit 22 is connected between the input end of the IC element 2 connected to the output end of the sensor element 1 and the second power supply voltage line V _DD2 with the input end side being the anode side. and third diode D _3, a fourth diode D ₄ Metropolitan to the input end is connected as the cathode side between the input terminal and the second ground line V _GND2. Therefore, the second ESD protection circuit 22 can have a simple circuit configuration including a series circuit of two diodes D ₃ and D ₄ .

In FIG. 1 (b), it is represented the diode D ₁ to D ₄ as respective current sources I ₁ ~I _4. Note that the potential of the first power supply voltage line V _DD1 is the same as the potential of the second power supply voltage line V _DD2 . The potential of the first ground line V _{GND1 and} the potential of the second ground line V _GND2 are the same. In the sensor device of this embodiment, the sensor element 1 and the IC element 2 are accommodated in one package (not shown).

  As the sensor element 1, for example, an infrared sensor chip in which a sensor unit 11 made of a thermopile and a first ESD protection circuit 12 are formed on one surface side of a first silicon substrate can be used. The sensor unit 11 of the sensor element 1 is not limited to a thermopile, and may be a thermistor, for example. The sensor unit 11 of the sensor element 1 is not limited to these, and may be a voltage output type physical quantity sensor part or chemical quantity sensor part. In any case, in the sensor element 1, the sensor unit 11 generates an analog output voltage.

  As the IC element 2, for example, an IC chip in which the amplifier circuit 23, the A / D conversion circuit 24, the digital circuit 25, and the control unit 26 are formed on the second silicon substrate can be used as the signal processing circuit 21.

  As the amplifier circuit 23, for example, a chopper amplifier can be used, but an amplifier other than the chopper amplifier can also be used.

  As the A / D conversion circuit 24, for example, an integral A / D converter such as a single integral A / D converter or a double integral A / D converter can be used. Further, as the A / D conversion circuit 24, a comparison type A / D converter such as a follow-up comparison type A / D converter or a successive approximation type A / D converter can be used.

  The control unit 26 has a function of controlling the amplifier circuit 23, the A / D conversion circuit 24, the digital circuit 25, and the like. The control unit 26 may be configured by a microcomputer equipped with an appropriate program, or may be configured by a combination of a timing control circuit and a plurality of circuits each designed to realize a desired function. .

The offset canceling means 3 includes a first analog switch SW1 provided between the sensor unit 11 and the output terminal on the high potential side of the sensor element 1, an output terminal on the high potential side of the sensor element 1, and a first ground. A second analog switch SW2 provided between the line _VGND1 and a series circuit of a leakage current detection resistor Rc is provided. The offset canceling means 3 includes the above-described control unit 26 provided in the IC element 2 and having a function of controlling the first analog switch SW1 and the second analog switch SW2, and the above-described digital circuit 25. . The first analog switch SW1 and the second analog switch SW2 are preferably composed of n-channel MOS transistors, which can reduce the on-resistance as compared with the case where they are composed of p-channel MOS transistors and can operate at high speed. Is possible. The series circuit of the second analog switch SW2 and the leakage current detection resistor Rc is not between the output terminal on the high potential side of the sensor element 1 and the first ground line _VGND1 , but on the input terminal of the IC element 2 (here. Then, it may be provided between the input terminal of the amplifier circuit 23) and the second ground line _VGND2 .

The digital circuit 25 divides the first input voltage V _C1 when the first analog switch SW1 is turned off and the second analog switch SW2 is turned on by the control unit 26 by the resistance value of the leakage current detection resistor Rc. a first arithmetic unit 25 ₁ for obtaining a leakage current value by, from the second input voltage V _C2 in a state where the control unit 26 first analog switch SW1 is turned on and the second analog switch SW2 is turned off And a second arithmetic unit 25 ₂ for obtaining a value obtained by subtracting the product of the leakage current value and the impedance of the sensor unit 11 (here, the resistance value of the resistor Rs). Here, the digital circuit 25 includes a memory 25 _{3 in} which the resistance value of the leakage current detection resistor Rc and the resistance value of the resistor Rs are stored in advance. Further, the resistance value of the leakage current detection resistor Rc and the resistance value of the resistor Rs are not necessarily stored in the memory 25 ₃ , and may be known in the first calculation unit 25 ₁ and the second calculation unit 25 _2, respectively. . The resistance values of the leakage current detection resistor Rc and the resistor Rs used for the calculation in the digital circuit 25 may be an actually measured value measured in advance or an estimated value from a measured value in a TEG (test element group), or may be a design value. Good.

Here, if the current value of the leakage current I _L (the leakage current value) I _L, the resistance value of the leakage current detection resistor Rc Rc, the resistance value of the resistor Rs and Rs, the first input voltage V _C1, The second input voltage V _C2 is expressed by the following equations (1) and (2), respectively.

Thus, (1) As can be seen from the equation, the first computing section 25 _1, be determined leakage current I _L by the first input voltage V _C1 is divided by the resistance value of the leakage current detection resistor Rc it can.

Also, knowing the leakage current I _L in equation (1), the second operation unit 25 _2, the impedance (in this case the leakage current I _L and the sensor unit 11 from the second input voltage V _C2, a resistor Rs the value obtained by subtracting the product of the resistance value), that is, it is possible from the output voltage of the sensor unit 11 to obtain a value obtained by canceling the offset voltage (noise voltage) determined by the impedance of the leakage current I _L and the sensor unit 11.

In the sensor device of the present embodiment described above, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively, thereby preventing destruction due to ESD. It becomes possible to do. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

In the sensor device of the present embodiment, the offset canceling means 3 includes the first analog switch SW1, the series circuit of the second analog switch SW2, and the leakage current detection resistor Rc, the control unit 26, By providing the digital circuit 25, it becomes possible to cancel the offset voltage determined by the leakage current I _L and the impedance of the sensor unit 11 with a relatively simple configuration, and high accuracy by improving the S / N ratio. Can be achieved.

(Embodiment 2)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The sensor device of this embodiment is different from the sensor device of Embodiment 1 in that the second analog switch SW2 in the sensor device of Embodiment 1 is not provided.

Therefore, the offset canceling means 3 in the sensor device of the present embodiment includes an analog switch SW1 provided between the sensor unit 11 and the output terminal, and between the output terminal of the sensor element 1 and the first ground line _VGND1. Is provided with a leakage current detection resistor Rc, a control unit 26 provided in the IC element 2 and having a function of controlling the analog switch SW1, and a digital circuit 25. The leakage current detection resistor Rc may be provided not between the output terminal of the sensor element 1 and the first ground line V _GND1 but between the input terminal of the IC element 2 and the second ground line V _GND2. .

  In the sensor device of this embodiment, the resistance value of the leakage current detection resistor Rc is set to the resistance Rs to such an extent that the combined resistance when the leakage current detection resistance Rc and the resistance Rs are connected in parallel can be approximated by the resistance value of the resistance Rs. It is preferable to set a value sufficiently larger than the resistance value.

  Here, the combined resistance R when the leakage current detection resistor Rc and the resistor Rs are connected in parallel is expressed by the following equation (3).

  If the resistance value of the leakage current detection resistor Rc is n times the resistance value of the resistor Rs, the combined resistor R can be expressed by the following equation (4).

  And mathematically, the following equation (5) is established.

  Therefore, in order to approximate the combined resistance R with the resistance value of the resistor Rs, it is necessary to make n sufficiently large. In other words, the resistance value of the leakage current detection resistor Rc needs to be sufficiently larger than the resistance value of the resistor Rs. There is. Here, the resistance value of the leakage current detection resistor Rc is preferably larger than the resistance value of the resistor Rs, but in practice, a chip (sensor element 1 or IC element 2) provided with the leakage current detection resistor Rc. ) Is limited by the relationship between the size, layout, and impurity concentration.

The digital circuit 25, first to obtain the leakage current I _L of the first input voltage V _C1 in the state where the analog switch SW1 is turned off by the control unit 26 by dividing by the resistance value of the leakage current detection resistor Rc The leak current value _IL and the impedance of the sensor unit 11 (here, the resistance value of the resistor Rs) from the second input voltage V _{C2 when the} analog switch SW1 is turned on by the arithmetic unit 25 ₁ and the control unit 26 And a second arithmetic unit 25 ₂ for obtaining a value obtained by subtracting the product of The control unit 26 also has a function of controlling the amplifier circuit 23, the A / D conversion circuit 24, the digital circuit 25, and the like as in the first embodiment.

Here, the first input voltage V _C1 and the second input voltage V _C2 are expressed by the following equations (6) and (7), respectively.

Thus, (6) As can be seen from equation The first operation unit 25 _1, be determined leakage current I _L by the first input voltage V _C1 is divided by the resistance value of the leakage current detection resistor Rc it can.

Further, (6) in the leakage current I _L is known, the second operation unit 25 _2, the impedance (in this case the leakage current I _L and the sensor unit 11 from the second input voltage V _C2, a resistor Rs the value obtained by subtracting the product of the resistance value), that is, from the output voltage of the sensor unit 11, it is possible to obtain a cancellation value offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

Further, in the sensor device of this embodiment, the offset canceling means 3 includes the analog switch SW1, the leakage current detection resistor Rc, the control unit 26, and the digital circuit 25 described above, so that it is relatively simple. in Do arrangement, it is possible to cancel the offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11, it is possible to improve the accuracy by improving the S / N ratio. Further, in the sensor device of the present embodiment, the second analog switch SW2 described in the first embodiment is not necessary, so that it is possible to cancel the offset voltage with a simpler configuration compared to the embodiment. .

(Embodiment 3)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

The sensor device of this embodiment includes a series circuit of a first power supply voltage line V _DD1 and the current source is provided between the high-potential side output end of the sensor element 1 I _R and the third analog switch SW3 And the configuration of the digital circuit 25 are different from those of the sensor device of the first embodiment.

The offset canceling means 3 in the sensor device of the present embodiment includes a first analog switch SW1 provided between the sensor unit 11 and the output terminal on the high potential side of the sensor element 1, and a high potential side of the sensor element 1. A second analog switch SW2 provided between the output terminal and the first ground line _VGND1 and a series circuit of a leakage current detection resistor Rc are provided.

Also, the offset canceling means 3 is provided with a series circuit of a first power supply voltage line V _DD1 and the current source is provided between the high-potential side output end of the sensor element 1 I _R and the third analog switch SW3 ing. The offset canceling means 3 includes a control unit 26 that is provided in the IC element 2 and has a function of controlling the first analog switch SW1, the second analog switch SW2, and the third analog switch SW3. The control unit 26 also has a function of controlling the amplifier circuit 23, the A / D conversion circuit 24, the digital circuit 25, and the like as in the first embodiment.

The current source I _R is a constant current source. The current source I _R can be configured by, for example, a current mirror circuit and a reference current source that applies a reference current to the current mirror circuit, but the configuration of the current source I _R is not particularly limited. The third analog switch SW3 is preferably composed of an n-channel MOS transistor, whereby the on-resistance can be reduced and high-speed operation is possible as compared with the case where the third analog switch SW3 is composed of a p-channel MOS transistor.

The series circuit of the second analog switch SW2 and the leakage current detection resistor Rc is not between the output terminal on the high potential side of the sensor element 1 and the first ground line _VGND1 , but on the input terminal of the IC element 2 and the first circuit. You may provide between 2 ground lines. Further, a series circuit of a current source I _R and the third analog switch SW3, instead of between the first power supply voltage line V _DD1 and the high potential side of the output end of the sensor element 1, a second power supply voltage line V You may provide between _DD2 and the input terminal of IC element 2. FIG.

In the sensor device of this embodiment, it is assumed that the resistance value of the leakage current detection resistor Rc and the resistance value of the resistor Rs are unknown values. This is because the resistance values of the leakage current detection resistor Rc and the resistor Rs may deviate from the design values due to manufacturing variations, errors, temperature fluctuations, and the like. In the sensor device of the present embodiment, it is preferable to set the current value of the current source I _R to a value sufficiently than the leakage current value I _L. Furthermore, the sensor device of the present embodiment, than the product of the current value of the current source I _R and the resistor Rs, as the voltage value of the voltage source Vs corresponding to the signal voltage is sufficiently small, the current source I _R It is preferable to set the current value.

Here, the current value of the current source I _R I _R, the current value of the current source I _R, when is n times the leakage current I _L, a first analog switch SW1 is off and the second analog switch The first input voltage V _C11 of the digital circuit 25 in a state where SW2 is on and the third analog switch SW3 is on can be expressed by the following equation (8).

  And mathematically, the following equation (9) holds.

Therefore, in order to approximate V _C11 by I _R × Rc, n needs to be sufficiently large, in other words, the current value of the current source I _R needs to be sufficiently larger than the leakage current value I _L.

The current source I product of the current value and the resistance Rs of _R is, when an m times the voltage value of the voltage source Vs (signal voltage), a first analog switch SW1 is turned on and the second analog switch SW2 The second input voltage V _C12 in a state where is turned off and the third analog switch SW3 is turned on can be expressed by the following equation (10).

  And mathematically, the following equation (11) is established.

Therefore, in order to approximate V _C12 by I _R × Rs, m needs to be sufficiently large. In other words, the product of the current value of the current source I _R and the resistance Rs is larger than the voltage value of the voltage source Vs. It needs to be large enough.

The digital circuit 25 supplies the first input voltage V _C11 as a current source when the control unit 26 turns off the first analog switch SW1, turns on the second analog switch SW2, and turns on the third analog switch SW3. It obtains the resistance value of the leakage current detection resistor Rc by dividing by the current value of I _R, a first analog switch SW1 is turned on and the second analog switch SW2 is turned off by the control unit 26 and third analog switches SW3 There the second input voltage V _C12 in a state of being turned on current source impedance of the sensor unit 11 by dividing (here, the resistance value of the resistor Rs) by the current value of I _R a preliminary calculation unit 25 ₀ to determine the I have.

In addition, the digital circuit 25 outputs the third input voltage V _C13 when the first analog switch SW1 is turned off, the second analog switch SW2 is turned on, and the third analog switch SW3 is turned off by the control unit 26. and a first arithmetic unit 25 ₁ for obtaining a leakage current I _L by dividing by the resistance value of the leakage current detection resistor Rc obtained in the preliminary calculation unit 25 _0. Also, the digital circuit 25 starts from the fourth input voltage V _{C14 when} the first analog switch SW1 is turned on, the second analog switch SW2 is turned off, and the third analog switch SW3 is turned off by the control unit 26. and a second arithmetic unit 25 ₂ for obtaining a value obtained by subtracting the product of the impedance obtained by the leak current value I _L and the spare computing unit 25 _0.

Here, if the current value of the current source I _R is I _R , the resistance value of the leakage current detection resistor Rc is Rc, and the resistance value of the resistor Rs is Rs, the first input voltage V _C11 , the second input voltage V _C12 is represented by the following formulas (12) and (13), respectively.

Therefore, (12) As can be seen from the equation, the pre-processor 25 _0, can be obtained resistance value of the leakage current detection resistor Rc by dividing by the current value I _R of the first input voltage V _C11. Further, (13) As can be seen from the equation, the pre-processor 25 _0, can be obtained resistance value of the resistor Rs by dividing the second input voltage V _C12 by the current value I _R.

Further, the third input voltage V _C13 and the fourth input voltage V _C14 are expressed by the following equations (14) and (15), respectively.

Therefore, as can be seen from the equation (14), the first calculation unit 25 ₁ can determine the leakage current value I _L by dividing the third input voltage V _C13 by the resistance value of the resistor Rc.

Also, if the leakage current value I _L is known from the equation (14), the second calculation unit 25 ₂ determines the leakage current value I _L and the impedance of the sensor unit 11 (here, the resistance Rs) from the fourth input voltage V _C14 . the value obtained by subtracting the product of the resistance value), that is, it is possible from the output voltage of the sensor unit 11 to obtain a value obtained by canceling the offset voltage (noise voltage) determined by the impedance of the leakage current I _L and the sensor unit 11.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

Furthermore, the sensor device of the present embodiment, the offset canceling means 3, described above, the first analog switch SW1, a series circuit of a second analog switch SW2 resistor Rc, the current source I _R and the third analog Since the series circuit of the switch SW3, the control unit 26, and the digital circuit 25 are provided, the resistance value of the leakage current detection resistor Rc and the impedance of the sensor unit 11 (here, the resistance value of the resistor Rs) are unknown. even, it is possible to cancel the offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11, it is possible to improve the accuracy by improving the S / N ratio. Further, in the sensor device of the present embodiment, when the third analog switch SW3 is turned on, it is possible to suppress the self-heating of the sensor element 1 by shortening the on time, and the preliminary calculation unit 25 _0. It is possible to improve the accuracy of the resistance value of the leakage current detection resistor Rc and the impedance of the sensor unit 11 obtained by

  Therefore, in the sensor device of the present embodiment, it is possible to suppress changes in accuracy due to manufacturing variations and temperature fluctuations of the sensor unit 11 and the leakage current detection resistor Rc.

(Embodiment 4)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 3, and description is abbreviate | omitted.

The sensor device of this embodiment, the current source I _R is, like that are constituted by the variable current source is different from the sensor device of the third embodiment. In the following description, the current source I _R is also referred to as a variable current source I _R.

The offset canceling means 3 in the sensor device of the present embodiment includes a first analog switch SW1 provided between the sensor unit 11 and the output terminal on the high potential side of the sensor element 1, and a high potential side of the sensor element 1. A second analog switch SW2 provided between the output terminal and the first ground line _VGND1 and a series circuit of a leakage current detection resistor Rc are provided.

Also, the offset canceling means 3, a series circuit of a variable current source I _R and the third analog switch SW3 provided between the first power supply voltage line V _DD1 and the high potential side of the output end of the sensor element 1 I have.

The variable current source I _R includes a current mirror circuit having two MOS transistors M1 and M2 whose gates are connected to each other, and a reference current to the current mirror circuit connected in series to one MOS transistor M1 of the current mirror circuit. and a reference current source I ₀ which gives, on the other MOS transistor M2, MOS transistors M3 and is connected a series circuit of a fourth analog switch SW4 in parallel. The fourth analog switch SW4 can be composed of a MOS transistor. The fourth analog switch SW4 is controlled by the control unit 26. Therefore, the variable current source I _R can change the current value of the variable current source I _R by controlling the fourth analog switch SW 4 by the control unit 26.

Also, the offset canceling means 3, a first analog switch SW1 provided on the IC device 2, a second analog switch SW2, the control unit 26 having a function of controlling the third analog switch SW3 and the variable current source I _R I have. The control unit 26 also has a function of controlling the amplifier circuit 23, the A / D conversion circuit 24, the digital circuit 25, and the like as in the first embodiment.

The digital circuit 25 (here, the resistance the resistance value of Rs) impedance of the sensor unit 11 and a pre-processor 25 ₀ for determining the resistance of and the current detection resistor Rc. Preliminary calculating unit 25 _0, the first analog switch SW1 is turned on and the second analog switch SW2 is turned off and the third analog switch SW3 is turned on by the control unit 26, the variable current source I _R is the first current value The first input voltage V _C21 in the state controlled to I ₁ and the second input voltage V in the state in which the variable current source I _R is controlled to the second current value I ₂ (I ₂ ≠ I ₁ ). The impedance of the sensor unit 11 is obtained by dividing the difference from _C22 by the difference between the first current value I ₁ and the second current value I ₂ . Also, pre-calculating unit 25 _0, the control unit 26 first analog switch SW1 is off and the second analog switch SW2 is turned on and the third analog switch SW3 is turned on, the variable current source I _R is a third The resistance value of the current detection resistor Rc is obtained by dividing the third input voltage V _C23 under the control of the current value I ₃ (I ₃ ≠ I ₂ ) by the third current value I ₃ .

Further, the digital circuit 25 outputs the fourth input voltage V _C24 in a state where the first analog switch SW1 is turned off, the second analog switch SW2 is turned on, and the third analog switch SW3 is turned off by the control unit 26. and a first arithmetic unit 25 ₁ for obtaining a leakage current I _L by dividing by the resistance value of the leakage current detection resistor Rc obtained in the preliminary calculation unit 25 _0. In addition, the digital circuit 25 starts from the fifth input voltage V _{C25 when} the first analog switch SW1 is turned on, the second analog switch SW2 is turned off, and the third analog switch SW3 is turned off by the control unit 26. and a second arithmetic unit for determining a value obtained by subtracting the product of the impedance obtained by the leak current value I _L and the spare computing unit 25 _0.

Here, the first input voltage V _C21 described above can be expressed by the following equation (16).

The second input voltage V _C22 described above can be expressed by the following equation (17).

From the equations (16) and (17), the difference between the first input voltage V _C21 and the second input voltage V _C22 can be expressed by the following equation (18).

The third input voltage V _C23 described above can be expressed by the following equation (19).

Therefore, (18) As can be seen from the equation, the pre-calculation unit _{25 0, | V C21 -V C22} | a | I ₁ -I ₂ | makes it possible to determine the resistance value of the resistor Rs by dividing. Further, (19) As can be seen from the equation, the pre-processor 25 _0, to obtain the resistance value of the leakage current detection resistor Rc by dividing a third input voltage V _C23 by the third current value I ₃ Can do.

The fourth input voltage V _C24 and the fifth input voltage V _C25 are expressed by the following formulas (20) and (21), respectively.

Therefore, (20) As can be seen from the equation, the first computing section 25 _1, it is determined leakage current I _L by the fourth input voltage V _C24 dividing by the resistance value of the leakage current detection resistor Rc it can.

Further, if the leakage current value I _L is known from the equation (20), as can be understood from the equation (21), the second calculation unit 25 ₂ calculates the leakage current value I _L and the sensor unit 11 from the fifth input voltage V _C25. The offset voltage (noise voltage) determined by the leakage current I _L and the impedance of the sensor unit 11 from the output voltage of the sensor unit 11 is subtracted from the product of the impedance (here, the resistance value of the resistor Rs). Canceled values can be obtained.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

In the sensor device of the present embodiment, the offset canceling means 3 includes the first analog switch SW1, the series circuit of the second analog switch SW2 and the leakage current detection resistor Rc, and the current source I _R. Since the series circuit of the third analog switch SW3, the control unit 26, and the digital circuit 25 are provided, the resistance value of the leakage current detection resistor Rc, the impedance of the sensor unit 11 (here, the resistance value of the resistor Rs) ) even if unknown, it is possible to cancel the offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11, it is possible to improve the accuracy by improving the S / N ratio.

  Further, in the sensor device of the present embodiment, it is possible to suppress changes in accuracy due to manufacturing variations and temperature fluctuations of the sensor unit 11 and the leakage current detection resistor Rc.

(Embodiment 5)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  The sensor device of this embodiment is different in that the sensor element 1 includes a plurality of sensor units 11.

The offset canceling means 3 in the sensor device of the present embodiment includes a dummy sensor unit 11D provided in the sensor element 1 and having the same configuration as the sensor unit 11, and an output terminal on the high potential side of the dummy sensor unit 11D and the sensor element 1. And a first analog switch SW11 provided between the first and second analog switches SW11. Here, the dummy sensor unit 11D having the same configuration as the sensor unit 11 means that the specifications are the same, and that the characteristics of the dummy sensor unit 11D are substantially the same as the characteristics of the sensor unit 11. . Therefore, if the voltage of the voltage source Vs ₁ corresponding to the signal voltage of the output voltage of the sensor unit 11 is Vs and the resistance value of the resistor Rs ₁ corresponding to the impedance of the sensor unit 11 is Rs, the output voltage of the dummy sensor unit 11D. The voltage of the voltage source Vs ₂ corresponding to the signal voltage Vs can be regarded as Vs, and the resistance value of the resistor Rs ₂ corresponding to the impedance of the dummy sensor unit 11D can be regarded as Rs.

  As the sensor element 1, for example, a plurality of pixel units each including a temperature sensing unit and a MOS transistor for taking out an output voltage of the temperature sensing unit like an infrared array sensor disclosed in Japanese Patent Application Laid-Open No. 2010-237117 However, a semiconductor substrate (silicon substrate) that is arranged in a two-dimensional array on the one surface side and that can read out the outputs of all the temperature sensing parts in time series can be used. In this case, each of the temperature sensing parts constitutes the sensor part 11, and each of the MOS transistors constitutes the second analog switch SW12. Further, by providing a dummy temperature sensing part having the same configuration as the temperature sensing part, this dummy temperature sensing part constitutes the dummy sensor part 11D. When this infrared array sensor is used as a temperature sensor, a Peltier element that keeps the temperature of the cold junction of the thermopile in the temperature sensing part at a constant temperature by keeping the temperature of the semiconductor substrate constant, or cold junction It is preferable to provide a thermistor for detecting the temperature.

  The offset canceling means 3 includes a plurality of second analog switches SW12 provided between each sensor unit 11 and the output terminal on the high potential side of the sensor element 1, and a first analog switch provided in the IC element 2. And a control unit 26 having a function of controlling the analog switch SW11 and each second analog switch SW12.

In addition, the digital circuit 25 starts from the first input voltage V ₃₁ in a state where the first analog switch SW11 is turned off and one second analog switch SW12 is turned on by the control unit 26. And a first arithmetic unit 25 ₃₁ that obtains an offset voltage by multiplying 2 by a value obtained by subtracting the second input voltage V ₃₂ in a state where the second analog switch SW12 is turned on. . The digital circuit 25, and a second arithmetic unit 25 ₃₂ determine the value of the offset voltage obtained by subtracting obtained from the first input voltage V ₃₁ at the first arithmetic unit 25 _31.

The first input voltage V ₃₁ described above and the second input voltage V _C32 are expressed by the following equations (22) and (23), respectively.

Therefore, the first calculation unit 25 ₃₁ can obtain the offset voltage represented by the following equation (24).

Then, in the second operation unit 25 _32, (25) below, it is possible to obtain a value of the offset voltage obtained by subtracting obtained from the first input voltage V ₃₁ at the first arithmetic unit 25 _31.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

  In the sensor device of this embodiment, the dummy sensor part 11D can be formed simultaneously with the sensor part 11 at the time of manufacture, and the first switching element SW11 can be formed simultaneously with each second switching element SW12. Since it is possible, it is not necessary to add a process for forming the leakage current detection resistor Rc as in the first embodiment, the manufacturing process can be simplified, and the manufacturing cost can be reduced. .

(Embodiment 6)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

In the sensor device of the present embodiment, the sensor element 1 includes a plurality of sensor units 11 and a plurality of analog switches SW1 provided between each sensor unit 11 and the output terminal on the high potential side of the sensor element 1 (description) For example, a plurality of analog switches SW1 may be referred to as analog switches SW1 _{1 to} SW1 _n ).

Here, the plurality of sensor units 11 have the same configuration. In short, the multiple sensor units 11 have the same specifications and substantially the same characteristics. Therefore, the voltage Vs _n of the voltage source Vs ₁ corresponding to the signal voltage of the output voltage of each sensor unit 11 is Vs, and the resistance values of the resistors Rs ₁ to Rs _n corresponding to the impedance of each sensor unit 11 are Rs. Can be considered.

  The offset canceling means 3 in the sensor device of the present embodiment includes a control unit 26 that is provided in the IC element 2 and has a function of controlling each analog switch SW1.

The digital circuit 25 in the offset canceling unit 3 includes a first calculation unit ₂₅₄₁ and a second calculation unit ₂₅₄₂ . The first arithmetic unit ₂₅₄₁ is configured such that one first analog switch SW1 (for example, the first analog switch SW1 ₁ ) is turned on by the control unit 26 and the other _one first analog switch SW1 (for example, the first analog switch SW1) The first input voltage V ₄₁ when the analog switch SW1 ₂ ) is turned off, the one first analog switch SW1 is on, and the other one first analog switch SW1 is off. The offset voltage caused by the leak current I _L is obtained by multiplying the difference from the second input voltage V ₄₂ by 2.

The second arithmetic unit 25 ₄₂ calculates a value of the offset voltage obtained by subtracting determined by the second input voltage V ₄₂ from the first operation unit 25 _41.

The first input voltage V ₄₁ and the second input voltage V _C42 are expressed by the following equations (26) and (27), respectively.

Thus, the first operation unit 25 _41, it is possible to determine the offset voltage represented by (28) below.

Then, in the second operation unit 25 _42, at (29) below, it is possible to obtain a value of the offset voltage obtained by subtracting obtained from the second input voltage V ₄₂ at the first arithmetic unit 25 _41.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

  Further, in the sensor device of this embodiment, it is not necessary to add a special configuration for the offset canceling means 3 to the sensor element 1, and a process for forming the leakage current detection resistor Rc as in the first embodiment is performed. Since it is not necessary to add, the cost increase of the sensor element 1 can be prevented.

(Embodiment 7)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

In the sensor device of the present embodiment, the sensor element 1 includes a plurality of sensor units 11 and a plurality of analog switches SW1 provided between each sensor unit 11 and the output terminal on the high potential side of the sensor element 1 (description) For example, a plurality of analog switches SW1 may be referred to as analog switches SW1 _{1 to} SW1 _n ).

Here, the plurality of sensor units 11 have the same configuration. In short, the multiple sensor units 11 have the same specifications and substantially the same characteristics. Therefore, the voltage Vs _n of the voltage source Vs ₁ corresponding to the signal voltage of the output voltage of each sensor unit 11 is Vs, and the resistance values of the resistors Rs ₁ to Rs _n corresponding to the impedance of each sensor unit 11 are Rs. Can be considered.

  The offset canceling means 3 in the sensor device of the present embodiment includes a control unit 26 that is provided in the IC element 2 and has a function of controlling each analog switch SW1.

The digital circuit 25 in the offset means 3 is controlled by the control unit 26 from the first input voltage V ₅₁ in a state where one of the two analog switches SW1 randomly selected by the control unit 26 is on and the other is off. By multiplying the value obtained by subtracting the average value obtained by accumulating the second input voltage V ₅₂ in the state in which both of the two analog switches SW1 selected at random with the two are turned on and dividing by the number of accumulations, by 2. a first operation unit 25 ₅₁ for obtaining an offset voltage, and a second arithmetic unit 25 ₅₂ determine the value of the offset voltage is subtracted from the first input voltage V _51.

Here, the control unit 26 includes a pseudo-random number generation circuit 26a for randomly selecting any two analog switches SW1 from a plurality (for example, 64) of analog switches SW, and a counter for counting the number of accumulations described above. 26b. The first calculation unit 25 ₅₁ includes an accumulation circuit 25 ₅₁₁ that accumulates the second input voltage V ₅₂ , and a divider that divides the output of the accumulation circuit 25 ₅₁₁ by the number of accumulations provided from the control unit 26. 25 ₅₁₂ . The count value of the accumulated value and the counter 26b in the accumulator circuit 25 ₅₁₁ is reset each time it is performed an operation in the second operation unit 25 _52.

The first input voltage V ₅₁ described above and the second input voltage V _C52 are expressed by the following equations (30) and (31), respectively.

Therefore, in the first calculation unit 25 ₃₁ , the offset voltage represented by the following equation (32) can be obtained if the average value of the second input voltage V _C52 is V _C52ave .

The second operation unit 25 _52, the following equation (33) can be obtained Vs corresponding to the signal voltage.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

  Further, in the sensor device of this embodiment, it is not necessary to add a special configuration for the offset canceling means 3 to the sensor element 1, and a process for forming the leakage current detection resistor Rc as in the first embodiment is performed. Since it is not necessary to add, the cost increase of the sensor element 1 can be prevented.

Further, in the sensor device of the present embodiment, the offset voltage is obtained using the average value V _C52ave of the second input voltage V _C52 , so that it is possible to reduce the influence of the impedance variation of the sensor unit 11.

(Embodiment 8)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

The offset canceling means 3 in the sensor device of the present embodiment includes a dummy sensor unit 11D provided in the sensor element 1 and having the same configuration as the sensor unit 11 and connected to the sensor unit 11 in antiparallel. Here, the dummy sensor unit 11D having the same configuration as the sensor unit 11 means that the specifications are the same, and that the characteristics of the dummy sensor unit 11D are substantially the same as the characteristics of the sensor unit 11. . Therefore, if the voltage of the voltage source Vs ₁ corresponding to the signal voltage of the output voltage of the sensor unit 11 is Vs and the resistance value of the resistor Rs ₁ corresponding to the impedance of the sensor unit 11 is Rs, the output voltage of the dummy sensor unit 11D. The voltage of the voltage source Vs ₂ corresponding to the signal voltage Vs can be regarded as Vs, and the resistance value of the resistor Rs ₂ corresponding to the impedance of the dummy sensor unit 11D can be regarded as Rs. The dummy sensor unit 11D and the sensor unit 11 have polarity, and the “−” side of the dummy sensor unit 11D is connected to the “+” side of the sensor unit 11, and the “+” side of the dummy sensor unit 11D is connected to the “+” side. By being connected to the “−” side of the sensor unit 11, they are connected in antiparallel. For example, when the sensor unit 11 and the dummy sensor unit 11D are thermopile, such a configuration to be connected in antiparallel is easily realized by appropriately designing the layout of the wiring connecting the sensor unit 11 and the dummy sensor unit 11D. it can.

  The offset cancel means 3 includes an analog switch SW1 provided between the dummy sensor unit 11D and the output terminal on the high potential side of the sensor element 1. The offset canceling means 3 includes a control unit 26 that is provided in the IC element 2 and has a function of controlling the analog switch SW1.

State The digital circuit 25 in the offset canceling means 3, the first input voltage V ₆₁ in the state where the analog switch SW1 is turned off by the control unit 26, which by the control unit 26 first analog switch SW1 is turned on and a calculation unit 25 ₆ to the second input voltage V ₆₂ obtains a value obtained by subtracting a multiplied by 2 in.

The first input voltage V ₆₁ described above and the second input voltage V _C62 are expressed by the following equations (34) and (35), respectively.

Thus, the arithmetic unit 25 _6, it is possible to determine the offset voltage represented by (36) below.

Further, the arithmetic unit 25 _6, by the following equation (37) can be obtained Vs corresponding to the signal voltage.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

Further, in the sensor device of the present embodiment, the dummy sensor unit 11D can be formed at the same time as the sensor unit 11 at the time of manufacture, so a process for forming the leakage current detection resistor Rc as in the first embodiment is added. This is not necessary, and the manufacturing process can be simplified and the manufacturing cost can be reduced. Further, in the sensor device of the present embodiment, the offset voltage can be easily obtained from the second input voltage V _C62 as shown in the above equation (36).

(Embodiment 9)
Below, the sensor apparatus of this embodiment is demonstrated based on FIG. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

The offset canceling means 3 in the sensor device of the present embodiment includes a first analog switch SW31 provided between the sensor unit 11 and the output terminal on the high potential side of the sensor element 1, and a high potential side of the sensor element 1. A first dummy sensor unit 11D ₁ , a second analog switch SW32, and a series circuit of the _second dummy sensor unit 11D ₂ provided between the output terminal and the first ground line V _GND1 are provided. . Also, the offset canceling means 3 is provided with a third analog switch SW33 connected in parallel to a series circuit of a second analog switch SW32 and the second dummy sensor portion 11D _2. Each of the analog switches SW31 to SW33 is preferably configured by an n-channel MOS transistor, thereby reducing the on-resistance and enabling a high-speed operation as compared with the case of configuring by a p-channel MOS transistor.

  Further, the offset canceling means 3 includes a control unit 26 provided in the IC element 2 and having a function of controlling the first analog switch SW31, the second analog switch SW32, and the third analog switch SW13.

In addition, the digital circuit 25 in the offset canceling means 3 is the first circuit when the first analog switch SW31 is turned off, the second analog switch SW2 is turned on, and the third analog switch SW33 is turned off by the control unit 26. a first operation unit 25 ₇₁ for obtaining an offset voltage by dividing the input voltage V ₇₁ at 2, a first analog switch SW31 is turned on by the control unit 26 and the second analog switch SW32 is turned off and the third analog switch A second operation unit ₂₅₇₂ that obtains a value obtained by subtracting the offset voltage from the second input voltage V ₇₁ in a state where the SW 33 is turned off.

Each of the first dummy sensor unit 11D ₁ and the second dummy sensor unit 11D ₂ is provided in the sensor element 1 and has the same configuration as the sensor unit 11. Further, the first dummy sensor unit 11D ₁ and the second dummy sensor unit 11D ₂ are connected in reverse series.

Here, the first dummy sensor unit 11D ₁ and the second dummy sensor unit 11D ₂ having the same configuration as the sensor unit 11 means that the specifications are the same, and the first dummy sensor unit 11D ₁ This means that the characteristics of the second dummy sensor unit 11D ₂ are substantially the same as the characteristics of the sensor unit 11. Therefore, if the voltage of the voltage source Vs corresponding to the signal voltage of the output voltage of the sensor unit 11 is Vs and the resistance value of the resistor Rs corresponding to the impedance of the sensor unit 11 is Rs, the output of each dummy sensor unit 11D1, 11D2 The voltage of the voltage sources Vs ₁ and Vs ₂ corresponding to the voltage signal voltage can be regarded as Vs, and the resistance values of the resistors Rs ₁ and Rs ₂ corresponding to the impedances of the dummy sensor portions 11D ₁ and 11D ₂ can be regarded as Rs. The dummy sensor units 11D ₁ and 11D ₂ and the sensor unit 11 have polarity, and the “+” side of the _first dummy sensor unit 11D ₁ is connected to the “+” side of the sensor unit 11; the first dummy sensor portion 11D ₁ "-" side is, via a second analog switch SW32 of the second dummy sensor portion 11D ₂ "-" is connected to the side of the second dummy sensor portion 11D ₂ " The “+” side is connected to the “−” side of the sensor unit 11. For example, when the sensor unit 11 and the dummy sensor units 11D ₁ and 11D ₂ are thermopile, such a connection relationship can be easily realized by appropriately designing the layout of the wiring that connects them.

The first input voltage V ₇₁ described above and the second input voltage V _C72 are expressed by the following equations (38) and (39), respectively.

Therefore, the first calculation unit ₂₅₇₁ can obtain the offset voltage represented by the following equation (40).

In the offset canceling means 3 in the sensor device of the present embodiment, the first input voltage V ₇₁ is determined by twice the impedance of the sensor unit 11 and the leakage current, so the impedance of the sensor unit 11 (resistance value of the resistor Rs) Even when the value is smaller than that of the first embodiment, the offset voltage can be obtained with high accuracy.

Further, in the second arithmetic unit 25 _72, the following equation (41) can be obtained Vs corresponding to the signal voltage.

In the sensor device of the present embodiment described above, as in the first embodiment, the sensor element 1 and the IC element 2 include the first ESD protection circuit 12 and the second ESD protection circuit 22, respectively. It is possible to prevent the destruction caused by the above. Then, the sensor device of the present embodiment, an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow to the sensor unit 11 due to the first ESD protection circuit 12 and the second ESD protection circuit 22 Since the offset canceling means 3 for canceling is provided, high accuracy can be achieved.

In the sensor device of the present embodiment, the first dummy sensor unit 11D ₁ can be used as the sensor unit 11. In this case, the offset voltage from the third input voltage V ₇₃ in a state where the first analog switch SW31 is turned off, the second analog switch SW2 is turned off, and the third analog switch SW33 is turned on by the control unit 26. Should be subtracted.

Here, the third input voltage V ₇₃ is expressed by the following equation (42).

Therefore, even when the first dummy sensor unit 11D ₁ is used as the sensor unit 11, the sensor device of the present embodiment causes the sensor unit 11 to be caused by the first ESD protection circuit 12 and the second ESD protection circuit 22. is provided with the offset canceling means 3 for canceling an offset voltage determined by the impedance of the leakage current I _L and the sensor unit 11 to flow, it is possible to improve the accuracy.

DESCRIPTION OF SYMBOLS 1 Sensor element 2 IC element 11 Sensor part 11D Dummy sensor part 11D ₁ 1st dummy sensor part 11D ₂ 2nd dummy sensor part 12 1st ESD protection circuit 21 Signal processing circuit 22 2nd ESD protection circuit 23 Amplifier circuit 24 A / D conversion circuit 25 Digital circuit 25 ₀ Preliminary operation unit 25 ₁ 1st operation unit 25 ₂ 2nd operation unit 25 ₃₁ 1st operation unit 25 ₃₂ 2nd operation unit 25 ₄₁ 1st operation unit 25 ₄₂ 2nd operation unit 25 ₅₁ 1st operation part 25 ₅₂ 2nd operation part 25 ₆ Operation part 26 Control part D ₁ 1st diode D ₂ 2nd diode D ₃ 3rd diode D ₄ 4th diode I ₁ 1st current source I ₂ Second current source I ₃ Third current source I ₄ Fourth current source I _R Current source (variable current source)
The first analog switch I _L leak current Rc leakage current detection resistor Rs resistor SW1 (analog switch)
SW2 Second analog switch SW3 Third analog switch SW4 Fourth analog switch SW11 First analog switch SW12 Second analog switch SW31 First analog switch SW32 Second analog switch SW33 Third analog switch V _DD1 First power voltage line V _DD2 Second power voltage line V _GND1 First ground line V _GND2 Second ground line V _C1 First input voltage V _C2 Second input voltage V _C11 First input voltage V _C12 second input voltage V _C13 third input voltage V _C14 fourth input voltage V _C21 first input voltage V _C22 second input voltage V _C23 third input voltage V _C24 fourth input voltage V _C25 fifth input voltage V _C31 first input voltage V _C32 second input voltage V _C41 first input voltage V _C42 second input voltage V _C51 first input voltage V _C52 first Input voltage V _C61 first input voltage V _C62 second input voltage V _C71 first input voltage V _C72 second input voltage

Claims (11)

  A sensor element that generates an analog output voltage corresponding to a physical quantity to be detected and a sensor element having a first ESD protection circuit, a signal processing circuit that processes the output voltage, and an IC element that has a second ESD protection circuit And canceling an offset voltage determined by a leak current flowing through the sensor unit and an impedance of the sensor unit due to the first ESD protection circuit and the second ESD protection circuit A sensor device comprising offset canceling means.   The first ESD protection circuit includes a first diode connected between an output terminal on a high potential side of the sensor element and a first power supply voltage line with the output terminal side as an anode side, and the sensor element And a second diode connected between the output terminal and the first ground line with the output terminal side as a cathode side, and the second ESD protection circuit is connected to the output terminal of the sensor element. Between the input terminal of the IC element to be connected and the second power supply voltage line, a third diode connected with the input terminal side as the anode side, and between the input terminal and the second ground line The sensor device according to claim 1, comprising a fourth diode connected with the input end side as a cathode side.   The offset canceling means includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or between the input terminal and the second ground. A control circuit having a function of controlling the first analog switch and the second analog switch provided in the IC element, and a series circuit of a second analog switch provided between the line and a leakage current detection resistor And a first input voltage in a state where the first analog switch is turned off and the second analog switch is turned on by the control unit and a leakage value by dividing the first input voltage by the resistance value of the leakage current detection resistor A first calculation unit for obtaining a current value, and the control unit turns on the first analog switch and turns off the second analog switch. Wherein the second input voltage at state leakage current sensor apparatus according to claim 2, characterized in that it comprises a second arithmetic unit for determining a value obtained by subtracting the product of the impedance.   The offset canceling means includes an analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or between the input terminal and the second ground line. A leakage current detection resistor provided in between, a control unit provided in the IC element and having a function of controlling the analog switch, and a first input voltage when the analog switch is turned off by the control unit Is divided by the resistance value of the resistor to obtain a leakage current value, and the leakage current value is calculated from the second input voltage when the first analog switch is turned on by the control unit. The sensor device according to claim 2, further comprising a second calculation unit that obtains a value obtained by subtracting a product of the impedance.   The offset canceling means includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or between the input terminal and the second ground. A series circuit of a second analog switch and a leakage current detection resistor provided between the first power supply voltage line and the output terminal, or the second power supply voltage line and the input terminal. And a function of controlling the first analog switch, the second analog switch, and the third analog switch provided in the IC element. And a control unit having the first analog switch off and the second analog switch on and the third analog switch by the control unit. The resistance value of the leakage current detection resistor is obtained by dividing the first input voltage in a state in which the first analog switch is turned on by the current value of the current source, and the control unit turns on the first analog switch and A preliminary calculation unit for obtaining the impedance by dividing a second input voltage in a state where the second analog switch is off and the third analog switch is on by a current value of the current source; and the control unit For the leakage current detection, wherein the preliminary calculation unit obtains the third input voltage when the first analog switch is off, the second analog switch is on, and the third analog switch is off. A first calculation unit that obtains a leakage current value by dividing by a resistance value of the resistor; and the control unit turns on the first analog switch and the second analog unit. A second arithmetic unit that obtains a value obtained by subtracting a product of the leakage current value and the impedance obtained by the preliminary arithmetic unit from a fourth input voltage in a state where the switch is off and the third analog switch is off The sensor device according to claim 2, further comprising:   The offset canceling means includes a first analog switch provided between the sensor unit and the output terminal, and between the output terminal and the first ground line or between the input terminal and the second ground. A series circuit of a second analog switch and a leakage current detection resistor provided between the line, a variable current source provided between the first power supply voltage line and the output terminal, and a third analog A series circuit of switches; a control unit provided in the IC element and having a function of controlling the first analog switch, the second analog switch, the third analog switch, and the variable current source; and the control unit The first analog switch is on, the second analog switch is off, and the third analog switch is on, and the variable current source is The difference between the first input voltage when the current value is controlled to the second current value and the second input voltage when the variable current source is controlled to the second current value is calculated as the first current value. The impedance of the sensor unit is obtained by dividing by the difference with the second current value, and the first analog switch is turned off and the second analog switch is turned on and the third analog switch is turned on by the control unit. The resistance value of the leakage current detection resistor is obtained by dividing the third input voltage by the third current value when the variable current source is controlled to the third current value. The preliminary calculation unit outputs a fourth input voltage in a state where the first analog switch is turned off, the second analog switch is turned on, and the third analog switch is turned off by the calculation unit and the control unit. The requested A first calculation unit that obtains a leakage current value by dividing by a resistance value of a current detection resistor, and the control unit turns on the first analog switch and turns off the second analog switch and the third And a second operation unit that obtains a value obtained by subtracting a product of the leakage current value and the impedance obtained by the preliminary operation unit from a fifth input voltage in a state where the analog switch is turned off. The sensor device according to claim 2.   The sensor element includes a plurality of the sensor units, and the offset canceling unit is provided in the sensor element and has the same configuration as the sensor unit, the dummy sensor unit, and the output terminal. A first analog switch provided between the sensor unit, a plurality of second analog switches provided between each of the sensor units and the output terminal, and the first analog switch provided in the IC element. A control unit having a function of controlling a switch and each of the second analog switches, and a first unit in a state where the first analog switch is turned off and one of the second analog switches is turned on by the control unit. The second input voltage in a state where the first analog switch is turned on and the one second analog switch is turned on is subtracted from the input voltage. 3. A first calculation unit that obtains the offset voltage by multiplying a value by 2 and a second calculation unit that obtains a value obtained by subtracting the offset voltage from the first input voltage. Sensor device.   The sensor element includes a plurality of sensor units and a plurality of analog switches provided between each of the sensor units and the output terminal, and the offset canceling unit is provided in the IC element. A control unit having a function of controlling each of the analog switches, and a first state in which one of the first analog switches is turned on and the other one of the first analog switches is turned off by the control unit. The offset voltage is obtained by multiplying the difference between the input voltage and the second input voltage in a state in which the one first analog switch is on and the other one first analog switch is off by two. 3. A first computing unit for obtaining the second computing unit, and a second computing unit for obtaining a value obtained by subtracting the offset voltage from the second input voltage. Capacitors apparatus.   The sensor element includes a plurality of sensor units and a plurality of analog switches provided between each of the sensor units and the output terminal, and the offset canceling unit is provided in the IC element. And a control unit having a function of controlling each analog switch, and a first input voltage in a state where one of the two analog switches randomly selected by the control unit is on and the other is off. The value obtained by subtracting the average value obtained by accumulating the second input voltage in the state where both of the two analog switches randomly selected by the control unit are turned on and dividing by the accumulated number is multiplied by 2. A first calculation unit for obtaining the offset voltage, and a second calculation unit for obtaining a value obtained by subtracting the offset voltage from the first input voltage. The sensor device of claim 2 wherein.   The offset canceling unit is provided between the dummy sensor unit and the output end, and a dummy sensor unit provided in the sensor element and having the same configuration as the sensor unit and connected in antiparallel to the sensor unit. From the first input voltage in a state where the analog switch is turned off by the control unit, the control unit provided in the IC element and having a function of controlling the analog switch. 3. The sensor device according to claim 2, further comprising an arithmetic unit that obtains a value obtained by subtracting a value obtained by multiplying the second input voltage by 2 in a state where the first analog switch is turned on.   The offset canceling means includes a first analog switch provided between the sensor unit and the output end, and a first dummy sensor unit provided between the output end and the first ground line. And a third analog switch connected in parallel to a series circuit of the second analog switch and the second dummy sensor unit; and a series circuit of the second analog switch and the second dummy sensor unit; A control unit provided in an IC element and having a function of controlling the first analog switch, the second analog switch, and the second analog switch; and the control unit turns off the first analog switch and the second analog switch. The offset voltage is obtained by dividing the first input voltage by 2 when the analog switch 2 is on and the third analog switch is off. And a first input unit in a state in which the first analog switch is turned on, the second analog switch is turned off, and the third analog switch is turned off by the control unit. A second calculation unit that obtains a value obtained by subtracting an offset voltage, and each of the first dummy sensor unit and the second dummy sensor unit is provided in the sensor element and has the same configuration as the sensor unit. The sensor device according to claim 2, wherein the first dummy sensor unit and the second dummy sensor unit are connected in anti-series.

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