integrated circuits

Abstract

To provide an integrated circuit that can accurately measure ambient temperature. [Solution] An integrated circuit comprising: a bias current circuit 26 including a first resistor that generates a first bias current I1 based on the first resistor and a reference voltage; a second resistor to which the first bias current I1 is supplied; n diodes 50-52 connected in series to which the second bias current Ib is supplied; and a compensation circuit 55 that applies a compensation voltage corresponding to the voltage generated in the second resistor to the ground-side node of the n diodes 50-52, wherein the temperature coefficient of the second resistor is either positive or negative, and the temperature coefficient of the first resistor is one.

Description

Technical Field

[0001] The present invention relates to an integrated circuit. Background Art

[0002] Some integrated circuits include a temperature sensor such as a diode and are capable of detecting temperature (see, for example, Patent Documents 1 to 3). Prior Art Literature Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2020-134512 Patent Document 2 Japanese Unexamined Patent Application Publication No. 2024-34892 Patent Document 3 Japanese Unexamined Patent Application Publication No. 2006-324652 Summary of the Invention Problems to be Solved by the Invention

[0004] Incidentally, since a temperature sensor of an integrated circuit is affected by heat generated by the integrated circuit, it is generally impossible to accurately measure the temperature of the environment where the integrated circuit is arranged.

[0005] The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an integrated circuit capable of accurately measuring an environmental temperature. Means for Solving the Problems

[0006] The main aspect of the present invention that solves the aforementioned problems is an integrated circuit comprising: a bias current circuit including a first resistor that generates a first bias current based on the first resistor and a reference voltage; a second resistor to which the first bias current is supplied; n diodes connected in series to which the second bias current is supplied; and a compensation circuit that applies a compensation voltage corresponding to the voltage generated in the second resistor to the ground-side node of the n diodes, wherein the temperature coefficient of the second resistor is either positive or negative, and the temperature coefficient of the first resistor is either positive or negative.

[0007] The main aspect of the present invention that solves the aforementioned problems is an integrated circuit comprising: a bias current circuit including a first resistor that generates a bias current based on the first resistor and a reference voltage; n diodes connected in series to which the bias current is supplied; and a second resistor connected in series to the n diodes, wherein n is an integer of 1 or more, the temperature coefficient of the second resistor is either positive or negative, and the temperature coefficient of the first resistor is one of the two. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an integrated circuit that can accurately measure the temperature of the environment. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of an integrated circuit 10a. [Figure 2] This figure shows an example of a bias current circuit 26. [Figure 3] This figure shows an example of a temperature detection circuit 21a. [Figure 4] This is a diagram illustrating the temperature detected by the temperature sensor. [Figure 5] This figure shows an example of an integrated circuit 10b. [Figure 6] This figure shows an example of a temperature detection circuit 21b. [Modes for carrying out the invention]

[0010] This specification and the accompanying drawings make it clear at least the following matters. Furthermore, identical or equivalent components, members, etc., shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted where appropriate.

[0011] =====Integrated Circuit 10a===== Figure 1 is a diagram illustrating an example of the integrated circuit 10a of this embodiment.

[0012] The integrated circuit 10a is a circuit capable of detecting pressure and temperature. The integrated circuit 10a consists of a pressure sensor 20, a temperature detection circuit 21a, a multiplexer (MUX) 22, an analog-to-digital converter (hereinafter referred to as ADC) 23, an interface circuit (hereinafter referred to as IF circuit) 24, a control circuit 25, a bias current circuit 26, and terminals T1 and T2.

[0013] Terminal T1 is the terminal to which the power supply voltage Vcc for operating the integrated circuit 10a is applied. The power supply voltage Vcc is generated by an external power supply circuit (not shown) of the integrated circuit 10a.

[0014] Terminal T2 is a terminal through which information is exchanged between the integrated circuit 10a and an external device (for example, an ECU (Electronic Control Unit)). As will be described in detail later, in this embodiment, for example, the measured temperature and pressure are output from terminal T2.

[0015] The pressure sensor 20 is a sensor that outputs a voltage corresponding to the pressure. The pressure sensor 20 is, for example, a piezoresistor bridge circuit (not shown) formed on a silicon diaphragm, and the output of the pressure sensor 20 is output to the multiplexer 22. In this embodiment, the integrated circuit 10a includes the pressure sensor 20, but is not limited to this. For example, the pressure sensor 20 may be composed of a separate chip from the integrated circuit 10a, and only the output from the pressure sensor 20 may be output to the multiplexer 22.

[0016] The temperature detection circuit 21a is a circuit that detects the temperature of the environment where the integrated circuit 10a is arranged (hereinafter referred to as "environmental temperature Ta"). The environmental temperature Ta in the present embodiment is, for example, the temperature of the medium of the pressure sensor 20. Details of the temperature detection circuit 21a will be described later.

[0017] The multiplexer 22 selects either the output of the pressure sensor 20 or the output of the temperature detection circuit 21a based on an instruction from a control circuit 25 described later, for example, and outputs the selected output to the ADC 23.

[0018] The ADC 23 is a circuit that converts an analog signal output from the multiplexer 22 (here, an analog voltage) into a digital signal. The ADC 23 according to the present embodiment converts an analog signal into, for example, a 12-bit digital signal.

[0019] The IF circuit 24 is a circuit that exchanges various types of data between an internal circuit of the integrated circuit 10a and an external device (for example, an ECU (Electronic Control Unit)). Specifically, the IF circuit 24 transmits the digital signal from the ADC 23 to the external device. The IF circuit 24 also transmits an instruction from the external device to the control circuit 25.

[0020] The control circuit 25 is a circuit that performs overall control of the operation of the integrated circuit 10a. The control circuit 25 controls the multiplexer 22 and the IF circuit 24 by executing a program stored in a storage circuit (not shown), for example.

[0021] The bias current circuit 26 generates bias currents I1 and I2 for operating the temperature detection circuit 21a and the ADC 23, respectively. Although FIG. 1 illustrates that the bias current circuit 26 generates the bias currents I1 and I2, the bias current circuit 26 may also generate bias currents for other circuits (for example, the multiplexer 22, the IF circuit 24, and the control circuit 25).

[0022] <<<Bias Current Circuit 26>>> Figure 2 shows an example of a bias current circuit 26. The bias current circuit 26 is a circuit that generates bias currents I1 and I2 according to a reference voltage Vref and a resistor 100. The bias current circuit 26 is composed of a reference voltage circuit 40, an operational amplifier 41, an NMOS transistor 42, PMOS transistors 43 to 45, and a resistor 100.

[0023] The reference voltage circuit 40 is a circuit that generates a reference voltage Vref corresponding to the power supply voltage Vcc, and is composed of resistors 110 and 111. In this embodiment, the reference voltage circuit 40 divides the power supply voltage Vcc using resistors 110 and 111 connected in series, and outputs the divided voltage as the reference voltage Vref. Note that although the reference voltage circuit 40 divides the power supply voltage Vcc using two resistors 110 and 111, it is not limited to this, and may be divided using three or more resistors.

[0024] In this embodiment, resistors 110 and 111 are both polysilicon resistors. That is, when resistors 110 and 111 are manufactured in the integrated circuit 10a, the material of resistor 110 and the material of resistor 111 are the same. Therefore, the temperature characteristics of resistors 110 and 111 are also the same. As a result, the reference voltage Vref is a temperature-compensated voltage, although it depends on the power supply voltage Vcc.

[0025] In this embodiment, the reference voltage circuit 40 generates a reference voltage Vref corresponding to the power supply voltage Vcc, but it is not limited to this. For example, a bandgap reference voltage circuit may be used as the reference voltage circuit 40, and a voltage at a predetermined level independent of the power supply voltage Vcc and temperature may be output as the reference voltage Vref.

[0026] A reference voltage Vref is applied to the non-inverting input terminal of the operational amplifier 41, and its inverting input terminal is connected to the resistor 100. The output of the operational amplifier 41 is connected to the gate electrode of the NMOS transistor 42. Therefore, in this embodiment, the operational amplifier 41 controls the NMOS transistor 42 so that the voltage applied to the resistor 100 becomes the reference voltage Vref.

[0027] Here, if we let the resistance value of resistor 100 be R0, the reference current I0 flowing through resistor 100 is expressed by the following equation (1). I0 = Vref / R0 ... (1)

[0028] A diode-connected PMOS transistor 43 is connected to the drain electrode of the NMOS transistor 42. Furthermore, the power supply voltage Vcc is applied to the source electrode of the PMOS transistor 43. Therefore, a voltage corresponding to the reference current I0 is generated at the gate electrode of the PMOS transistor 43.

[0029] The gate electrode of PMOS transistor 43 is connected to the gate electrodes of PMOS transistors 44 and 45. Therefore, PMOS transistor 43 and PMOS transistors 44 and 45 form a current mirror circuit. Consequently, bias currents I1 and I2, corresponding to the reference current I0, flow through PMOS transistors 44 and 45.

[0030] In this embodiment, the bias current I1 from the PMOS transistor 44 is supplied to the temperature detection circuit 21a, and the bias current I2 from the PMOS transistor 45 is supplied to the ADC 23. The resistor 100 corresponds to the "first resistor," and the bias current I1 corresponds to the "first bias current," or the "bias current based on the first resistor and the reference voltage."

[0031] <<<Temperature detection circuit 21a>>> Figure 3 shows an example of a temperature detection circuit 21a. The temperature detection circuit 21a is a circuit that outputs a voltage Vt indicating the detected temperature (in this case, ambient temperature Ta) to the multiplexer 22. The temperature detection circuit 21a is composed of three diodes 50-52 and a resistor 101.

[0032] Diodes 50-52 are connected in series between the PMOS transistor 44 of the bias current circuit 26 and the resistor 101 (described later). The forward voltage Vf of each of the diodes 50-52 has a predetermined temperature characteristic (e.g., -2mV / °C). Therefore, in this embodiment, the temperature can be detected based on the temperature characteristic of the forward voltage Vf, which is proportional to the number of diodes.

[0033] The number of diodes included in the temperature detection circuit 21a is not limited to three; at least one is sufficient. However, providing multiple diodes, as in this embodiment, can increase the temperature detection sensitivity. In this embodiment, the voltage generated between the anode of diode 50, which is located closest to the power supply, and the cathode of diode 52, which is located closest to ground, is defined as "voltage Vd". Also, three corresponds to "n", and 3 corresponds to "an integer greater than or equal to 1".

[0034] Here, referring to Figure 4, we will explain the temperatures detected by diodes 50-52 and the temperature detection circuit 21a, respectively. The dashed line in Figure 4 shows an example of the voltage Vd output by the three diodes 50-52 to which the bias current I1 is supplied. In the dashed line in Figure 4, the three diodes 50-52 are used as temperature sensors.

[0035] In this embodiment, diodes 50 to 52 are formed on the integrated circuit 10a. Therefore, the temperature detected by diodes 50 to 52 is affected not only by the ambient temperature Ta but also by the temperature of the integrated circuit 10a (hereinafter referred to as "chip temperature Tc").

[0036] Here, if we consider the temperature detected by diodes 50-52 to be the sum of the ambient temperature Ta and the chip temperature Tc, then, for example, the voltage Vd will be the voltage V1 at point P1 in Figure 4. On the other hand, if diodes 50-52 detect only the ambient temperature Ta, the voltage Vd will be the voltage V2 at point P2 in Figure 4. Therefore, the voltage difference between voltage V2 and voltage V1 (hereinafter referred to as "voltage Vc") will correspond to the chip temperature Tc.

[0037] Therefore, if the voltage Vc corresponding to the chip temperature Tc can be added to the voltage Vd, the temperature detection circuit 21a can detect the ambient temperature Ta. The temperature detection circuit 21a in Figure 3 is a circuit that can add the voltage Vc to the voltage Vd of diodes 50 to 52. The temperature detection circuit 21a includes a resistor 101 for adding the voltage Vc.

[0038] When a bias current I1 is supplied, resistor 101 applies a voltage Vc, expressed by equation (2) below, to the cathode of diode 52. Here, the value of the bias current I1 is denoted as I1, and the resistance value of resistor 101 is denoted as R1. Note that the resistance value R1 is determined, for example, based on the standard chip temperature Tc of the integrated circuit 10a. Vc = I1 × R1 ... (2)

[0039] As described above, the bias current I1 in this embodiment changes according to the reference current I0. The reference current I0 is given by I0 = Vref / R0 from equation (1) above. Also, the reference voltage Vref in this embodiment is proportional to the power supply voltage Vcc. Therefore, the voltage Vc in equation (2) is expressed by the following equation (3). Vc∝(R1 / R0)×Vcc···(3)

[0040] <<Temperature coefficient>> Here, if we assume that the voltage Vc has a temperature coefficient, the temperature coefficient of the voltage Vt, which indicates the temperature detected by the temperature detection circuit 21a, will be affected not only by the temperature coefficient of the voltage Vd but also by the temperature coefficient of the voltage Vc. In such a case, the temperature coefficient of the voltage Vt will deviate significantly from the known temperature coefficient of the voltage Vd (for example, (-2mV / °C) × 3).

[0041] Therefore, in this embodiment, it is preferable that the temperature coefficient of the voltage Vc is approximately zero (i.e., that it is temperature compensated). In equation (3), the power supply voltage Vcc is generally generated by an external power supply circuit (not shown) and does not have temperature dependence. Therefore, if the temperature coefficient of resistor 100 and the temperature coefficient of resistor 101 are approximately the same, it is possible to temperature compensate the voltage Vc.

[0042] In this embodiment, both the resistor 100 of the bias current circuit 26 and the resistor 101 of the temperature detection circuit 21a are polysilicon resistors formed on the silicon substrate (not shown) of the integrated circuit 10a. When the material of resistor 100 and the material of resistor 101 are the same in this way, the temperature characteristics of resistors 100 and 101 can be made approximately equal, so the temperature coefficient of voltage Vc can be made almost zero.

[0043] As a result, the temperature detection circuit 21a can make the temperature coefficient of voltage Vt approximately equal to the temperature coefficient of voltage Vd. In this embodiment, the resistance value R1 of resistor 101 is set so that the magnitude of voltage Vc represents a typical chip temperature Tc. As a result, the temperature detection circuit 21a outputs a voltage Vt (=Vd+Vc) that represents the ambient temperature Ta. Therefore, by measuring the voltage Vt, the ambient temperature Ta can be determined with high accuracy. Note that resistor 101 corresponds to the "second resistor".

[0044] If resistors 100 and 101 are both polysilicon resistors, then, for example, the temperature coefficients of resistors 100 and 101 will be negative. Also, "the material of resistor 100 and the material of resistor 101 are the same" means that the materials used to manufacture the polysilicon resistor corresponding to resistor 100 (e.g., arsenic (As), phosphorus (P), boron (B)) are the same as the materials used to manufacture the polysilicon resistor of resistor 101. Note that as long as the materials of resistors 100 and 101 are the same, the dopant concentrations of each material may be different.

[0045] Here, resistors 100 and 101 are polysilicon resistors with negative temperature coefficients, but this is not the only option. For example, resistors 100 and 101 could each be offset resistors with positive temperature coefficients. It is preferable that the temperature coefficients of resistors 100 and 101 are equal, but at a minimum, the signs (positive or negative) of the temperature coefficients of resistors 100 and 101 should be the same. In other words, resistors 100 and 101 do not necessarily have to be made of the same material.

[0046] <<Manufacturing variations>> By the way, the resistance value R0 of resistor 100 in the bias current circuit 26 varies because it is a component manufactured on a silicon substrate (not shown). For example, if the resistance value R0 increases from a standard value, the reference current I0 decreases. As a result, the power consumption of the integrated circuit 10a decreases, and the chip temperature Tc decreases. On the other hand, for example, if the resistance value R0 decreases from a standard value, the reference current I0 increases. As a result, the power consumption of the integrated circuit 10a increases, and the chip temperature Tc rises.

[0047] Therefore, it is preferable that when the reference current I0 increases and the chip temperature Tc rises, the voltage Vc also increases, and when the reference current I0 decreases and the chip temperature Tc decreases, the voltage Vc decreases.

[0048] In this embodiment, resistors 100 and 101 are manufactured such that the variation in the resistance value R1 of resistor 101 is sufficiently smaller than the variation in the resistance value R0 of resistor 100. Therefore, even if the resistance value R0 changes significantly from the standard value, the resistance value R1 remains almost at the standard value. Consequently, even when the same material is used for resistors 100 and 101, a voltage Vc is obtained that rises when the reference current I0 increases and falls when the reference current I0 decreases.

[0049] As a result, the temperature detection circuit 21a can not only output a voltage Vt (=Vd+Vc) indicating the ambient temperature Ta, but can also change the magnitude of the voltage Vt according to the magnitude of the reference current I0. In other words, even if the chip temperature Tc changes due to the influence of the reference current I0, the temperature detection circuit 21a can output a voltage Vt in which the influence of the chip temperature Tc is suppressed. Therefore, in such cases, the ambient temperature Ta can be accurately determined by measuring the voltage Vt.

[0050] Furthermore, if both resistors 100 and 101 are polysilicon resistors, to make the variation in resistance value R1 smaller than the variation in resistance value R0, for example, the sheet resistance of resistor 101 should be made sufficiently smaller than the sheet resistance of resistor 100. This prevents the resistance value R1 from changing significantly even if the dopant concentration of the polysilicon resistor material of resistor 101 changes.

[0051] <<Dependence on power supply voltage Vcc>> Incidentally, when the power supply voltage Vcc applied to the integrated circuit 10a increases and the power consumption of the integrated circuit 10a increases, the chip temperature Tc also increases. Specifically, as shown in equation (3) above, the voltage Vc in this embodiment is proportional to the power supply voltage Vcc.

[0052] As a result, the temperature detection circuit 21a can not only output a voltage Vt (=Vd+Vc) indicating the ambient temperature Ta, but can also change the magnitude of the voltage Vt according to the magnitude of the power supply voltage Vcc. In other words, even if the chip temperature Tc changes due to the influence of the power supply voltage Vcc, the temperature detection circuit 21a can output a voltage Vt in which the influence of the power supply voltage Vcc is suppressed. Therefore, in such cases, the ambient temperature Ta can be accurately determined by measuring the voltage Vt.

[0053] ===== Integrated Circuit 10b ===== Figure 5 is a diagram illustrating an example of the integrated circuit 10b of this embodiment. The integrated circuit 10b is a circuit capable of detecting pressure and temperature. Furthermore, the bias current Ib (described later) can be set by an external resistor 11 of the integrated circuit 10b.

[0054] The integrated circuit 10b consists of a pressure sensor 20, a temperature detection circuit 21b, a multiplexer (MUX) 22, an ADC 23, an IF circuit 24, a control circuit 25, a bias current circuit 26, and terminals T1 to T3. Comparing the integrated circuit 10a in Figure 1 with the integrated circuit 10b in Figure 5, the configurations are the same except for the temperature detection circuit 21b and terminal T3. Therefore, the temperature detection circuit 21b and terminal T3 will be described here.

[0055] Terminal T3 is the terminal to which a bias current Ib from the power supply circuit (not shown) is supplied. The value of the bias current Ib is determined by the resistance value of resistor 11 connected between terminal T1 and terminal T3. Note that the bias current Ib corresponds to the "second bias current".

[0056] Figure 6 shows an example of a temperature detection circuit 21b. The temperature detection circuit 21b is a circuit that applies a voltage Vtemp indicating the ambient temperature Ta to terminal T3 and outputs it to the multiplexer 22, and is composed of three diodes 50-52, a compensation circuit 55, and a resistor 102. A resistor 11 located outside the integrated circuit 10b is connected between terminal T1, to which the power supply voltage Vcc is applied, and terminal T3. Therefore, a bias current Ib corresponding to the power supply voltage Vcc and the resistance value of resistor 11 is supplied to diodes 50-52.

[0057] Diodes 50-52 are connected in series between terminal T3 and resistor 121 (described later) of compensation circuit 55. Note that diodes 50-52 are the same as the three diodes in Figure 3 except for their connection relationships. Therefore, a detailed explanation of diodes 50-52 is omitted here.

[0058] Similar to resistor 101, resistor 102 generates a voltage Vcommp, represented by equation (4), when supplied with a bias current I1 from the bias current circuit 26. Here, the value of the bias current I1 is denoted as I1, and the resistance value of resistor 102 is denoted as R2. Note that the resistance value R2 is determined, for example, based on the typical chip temperature of the integrated circuit 10b. Vcommp = I1 × R2 ... (4)

[0059] As described above, the bias current I1 in this embodiment changes according to the reference current I0. The reference current I0 is given by I0 = Vref / R0 from equation (1) above. Also, the reference voltage Vref in this embodiment is proportional to the power supply voltage Vcc. Therefore, the voltage Vcommp in equation (4) is expressed by the following equation (5). Vcomp∝(R2 / R0)×Vcc···(5)

[0060] The compensation circuit 55 is a circuit that compensates the voltage Vd so that the temperature detected by the temperature detection circuit 21b becomes the ambient temperature Ta. Specifically, the compensation circuit 55 is a circuit that adds a compensation voltage Vc to the voltage Vd of diodes 50 to 52, and is composed of an operational amplifier 120 and a resistor 121.

[0061] The non-inverting input terminal of the operational amplifier 120 is connected to resistor 102, and the output of the operational amplifier 120 is connected to the inverting input terminal. Therefore, the operational amplifier 120 is equivalent to a so-called voltage follower, outputting the voltage Vcommp across resistor 102.

[0062] Resistor 121 is placed between the cathode of diode 52 and ground. The output of the operational amplifier 120, which acts as a voltage follower, is connected to diode 52 and resistor 121. Therefore, the voltage at the cathode of diode 52 is the voltage Vcommp.

[0063] Here, resistor 102 is a polysilicon resistor manufactured to have the same temperature characteristics and variability as resistor 101 in Figure 3. Therefore, the voltage Vcommp shown in equation (5) has the same characteristics (here, temperature characteristics, variability, and dependence on the power supply voltage Vcc) as the voltage Vc shown in equation (3). As a result, the voltage obtained by adding voltage Vcommp to voltage Vd is the voltage Vtemp.

[0064] Therefore, the temperature detection circuit 21b can output a voltage Vtemp that is less affected by the chip temperature and power supply voltage Vcc. For this reason, the ambient temperature Ta can be determined with high accuracy by measuring the voltage Vtemp. Note that resistor 102 corresponds to the "second resistor", resistor 11 corresponds to the "third resistor", and resistor 121 corresponds to the "fourth resistor".

[0065] =====Summary===== The integrated circuits 10a and 10b of this embodiment have been described above. For example, the integrated circuit 10b shown in Figure 5 is configured to include the temperature detection circuit 21b shown in Figure 6. The temperature detection circuit 21b includes a compensation circuit 55 that applies a voltage Vcomp to the ground-side nodes of the three diodes 52. Therefore, the temperature detection circuit 21b outputs a voltage Vtemp in which the influence of the chip temperature of the integrated circuit 10b is suppressed, and the ambient temperature Ta is measured with high accuracy.

[0066] Furthermore, in the integrated circuit 10b, a resistor 11 is connected between terminals T1 and T3. Therefore, the bias current Ib supplied to the diodes 50-52 of the temperature detection circuit 21b can be set using the resistor 11.

[0067] Furthermore, the compensation circuit 55 includes a resistor 121 connected to the cathode of diode 52 and a voltage follower (in this case, an operational amplifier 120) that applies a voltage Vcomp across resistor 121. Therefore, the voltage Vcomp can be set regardless of the current value of the bias current Ib.

[0068] Furthermore, for example, the integrated circuit 10a shown in Figure 1 is configured to include the temperature detection circuit 21a shown in Figure 3. In the temperature detection circuit 21a, a resistor 101 that generates a voltage Vc is connected to the ground node of the three diodes 52. Therefore, since the temperature detection circuit 21a outputs a voltage Vt that is less affected by the chip temperature of the integrated circuit 10a, the ambient temperature Ta can be measured with high accuracy.

[0069] Furthermore, in integrated circuit 10a, the material for resistor 100 and the material for resistor 101 are the same, and in integrated circuit 10b, the material for resistor 100 and the material for resistor 102 are the same. Therefore, the temperature dependence of voltages Vc and Vcommp can be made approximately zero.

[0070] Furthermore, in integrated circuit 10a, the variation in resistor 101 is smaller than the variation in resistor 100, and in integrated circuit 10b, the variation in resistor 102 is smaller than the variation in resistor 100. Therefore, the voltages Vc and Vcommp can be changed according to the power consumption.

[0071] Furthermore, the reference voltage circuit 40 outputs a reference voltage Vref obtained by dividing the power supply voltage Vcc. Therefore, the voltages Vc and Vcommp can be changed according to the power supply voltage Vcc.

[0072] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that equivalents thereof are included. [Explanation of Symbols]

[0073] 10a, 10b integrated circuits 11,100,101,102,110,111,121 resistance 20 Pressure Sensors 21a, 21b Temperature detection circuit 22 Multiplexer 23 ADC 24 IF circuit 25 Control circuits 26 Bias Current Circuit 40 Reference voltage circuit 41,120 operational amplifiers 42 NMOS transistors 43-45 PMOS transistors 50-52 diodes 55 Compensation circuit

Claims

1. A bias current circuit including a first resistor that generates a first bias current based on the first resistor and a reference voltage, The second resistor to which the first bias current is supplied, A second bias current is supplied, along with n diodes connected in series, A compensation circuit that applies a compensation voltage corresponding to the voltage generated in the second resistor to the ground-side node of the n diodes, Equipped with, Qn is an integer greater than or equal to 1, The temperature coefficient of the second resistor is either positive or negative, and the temperature coefficient of the first resistor is either positive or negative. Integrated circuit.

2. The integrated circuit according to claim 1, The terminals to which the power supply side nodes of the n diodes are connected are provided. A third resistor is connected to the aforementioned terminal to generate the second bias current from the power supply. Integrated circuit.

3. The integrated circuit according to claim 1, The aforementioned compensation circuit is A fourth resistor is provided between the aforementioned grounded node and the ground, A voltage follower that applies the compensation voltage to the fourth resistor based on the voltage generated in the second resistor, including, Integrated circuit.

4. A bias current circuit including a first resistor that generates a bias current based on the first resistor and a reference voltage, The bias current is supplied, and n diodes are connected in series, A second resistor connected in series with the aforementioned n diodes, Equipped with, Qn is an integer greater than or equal to 1, The temperature coefficient of the second resistor is either positive or negative, and the temperature coefficient of the first resistor is either positive or negative. Integrated circuit.

5. An integrated circuit according to any one of claims 1 to 4, The material of the second resistor and the material of the first resistor are the same. Integrated circuit.

6. The integrated circuit according to claim 5, The variation in the resistance value of the second resistor is smaller than the variation in the resistance value of the first resistor. Integrated circuit.

7. The integrated circuit according to claim 6, The system includes a reference voltage circuit that divides the power supply voltage to generate the reference voltage. Integrated circuit.

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