High-precision temperature measuring circuit easy to calibrate

Abstract

The present disclosure relates to a high precision temperature measurement circuit capable of easy calibration. Sensing calibration techniques are disclosed for permanently recording a calibration value of a measured value when manufacturing a temperature measurement circuit. An ambient simulation calibration circuit element configured to generate a calibration current simulating an ambient temperature is added to the temperature measurement circuit. The environmental simulation calibration circuit element operates to vary an output current of the temperature sensing circuit by an amount according to an ambient temperature in accordance with a set state value input from an external calibration device during plant calibration. During factory calibration, an external calibration device calculates a calibration value from an output value measured when changing a setting state of an environmental simulation calibration circuit element, and sets the calibration value in a temperature measurement circuit.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0093286, filed on July 15, 2024, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. TECHNICAL FIELD

[0002] Disclosed are techniques related to electronic circuits, particularly temperature measurement circuits for detecting temperature. BACKGROUND

[0003] Temperature measurement circuits measure temperature using circuit elements having characteristics that vary with temperature. For example, the threshold voltage in the forward current of a bipolar junction transistor (BJT) element is VT=kT / q, where k is the Boltzmann constant, q is the electron charge and varies with temperature. This temperature characteristic of a BJT element can be used to construct a proportional-to-absolute temperature (PTAT) circuit having an output that increases with temperature or a circuit having an output that decreases with temperature.

[0004] When constructing such a temperature measurement circuit, a process is required to measure and calibrate the output value at a standard temperature. Conventional one-point calibration determines a calibration value from an output value measured at one temperature, so that only the offset is calibrated, and thus the accuracy can decrease depending on the temperature. In contrast, known two-point calibration determines a calibration value from output values measured at two temperatures, so that both the offset and the slope can be calibrated, and thus the temperature can be accurately measured when compared to one-point calibration. However, since it is necessary to confirm the output by creating a low-temperature environment and a high-temperature environment for two-point calibration, the cost of creating an environment for calibration increases at the time of mass production. SUMMARY

[0005] Accordingly, the present application has been made keeping in mind the above-mentioned problems, and it is an object of the present application to reduce the cost due to two-point calibration.

[0006] It is another object of the present application to provide a temperature measurement circuit capable of reducing manufacturing cost while having high accuracy.

[0007] According to one aspect of the proposed application, an environment simulation calibration circuit element configured to generate a calibration current simulating an ambient temperature is added to the temperature measurement circuit. The environment simulation calibration circuit element operates to change the output current of the temperature sensing circuit by an amount of change according to the ambient temperature according to a setting state value input from an external calibration device during factory calibration. During factory calibration, the external calibration device calculates a calibration value from the output value measured when the setting state of the environment simulation calibration circuit element is changed, and sets the calibration value in the temperature measurement circuit.

[0008] According to a further aspect, the temperature measurement circuit digitizes the output of the temperature sensing circuit, adds a set calibration value thereto, and then outputs a resulting value.

[0009] According to a further aspect, in the temperature measurement circuit, a preamplification parameter of an analog-to-digital converter (A / D converter) configured to digitize the output of the temperature sensing circuit can be set to a value calculated using the environmental simulation calibration circuit element during factory calibration. BRIEF DESCRIPTION OF DRAWINGS

[0010] The above and other objects, features and other advantages of the present application will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Figure 1 is a block diagram illustrating a configuration of a temperature measurement circuit and a factory calibration system for the temperature measurement circuit according to an embodiment; Figure 2 a configuration of an environmental simulation calibration circuit element according to an embodiment is illustrated; Figure 3 is a flowchart illustrating a configuration of an embodiment of a method of designing an environmental simulation calibration circuit element; Figure 4 an embodiment of a temperature sensing circuit of Figure 1 is illustrated; Figure 5 is a flowchart illustrating a configuration of a method of calibrating a temperature measurement circuit according to an embodiment; and Figure 6 is a flowchart illustrating a configuration of a method of calibrating a temperature measurement circuit according to another embodiment. DETAILED DESCRIPTION

[0011] The above and other aspects are embodied by the embodiments described with reference to the accompanying drawings. It should be understood that components of each embodiment can be combined in various ways within the embodiments or combined with components of other embodiments unless there is any other mention or contradiction therebetween. Based on the principle that the inventor can appropriately define the concept of terms to describe the present application in the best way, the terms used in the present specification and claims should be interpreted as having the meaning and concept consistent with the described content or proposed technical idea. Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0012] <DESCRIPTION OF DEVICE INVENTION> According to one aspect of the proposed invention, an environment simulation calibration circuit element that generates a calibration current simulating an ambient temperature is added to the temperature measurement circuit. The environment simulation calibration circuit element operates to change the output current of the temperature sensing circuit by an amount corresponding to the ambient temperature according to a set state value input from an external calibration device during factory calibration. During factory calibration, the external calibration device calculates a calibration value from the measured output value while changing the set state of the environment simulation calibration circuit element, and sets the calibration value in the temperature measurement circuit.

[0013] Figure 1 is a block diagram showing the configuration of a temperature measurement circuit and a factory calibration system for the temperature measurement circuit according to an embodiment. As shown in the figure, the illustrative external calibration device includes a calibration processor 200 and a temperature setter 300. The temperature setter 300 is a device that contacts the upper surface of a semiconductor chip included in the temperature measurement circuit 100 to maintain its temperature at a reference temperature (in this case, at room temperature (23.5°C)), and can be configured as, for example, a Peltier element. The illustrative calibration processor 200 includes an input port 215 for receiving the output value of the temperature measurement circuit 100, which is the calibration target according to the proposed invention, recording ports 211 and 213 for recording calibration values, a control output port 230 for controlling the temperature setter 300 used for measurement, and a setting control port 250 for controlling the internal settings of the temperature measurement circuit 100.

[0014] According to one aspect, the temperature measurement circuit 100, which is the calibration target, includes a temperature sensing circuit 130, an environment simulation calibration circuit element 110, and a measurement value calibration circuit 150. The temperature measurement circuit 100 according to the proposed embodiment can be used as a temperature sensor on its own, or can be included as part of a circuit inside another semiconductor device. The temperature sensing circuit 130 is a circuit that has a characteristic that changes with temperature. Electronic devices can have characteristics in which a certain current characteristic changes with temperature, because the movement of charge-carrying carriers is affected by temperature. For example, in the forward current of a BJT element, the threshold voltage is proportional to temperature according to the equation VT=kT / q, where k is the Boltzmann constant and q is the electronic charge. Temperature sensing circuits that have an output that is proportional to the temperature in the operating range by utilizing this characteristic are known.

[0015] The environmental simulation calibration circuit element 110 is connected to the temperature sensing circuit 130 and changes the output current of the temperature sensing circuit 130 according to a set state value input from an external calibration device during factory calibration. In the illustrated embodiment, the environmental simulation calibration circuit element 110 is implemented as a variable resistor 110 having different values according to the set state value input from the external calibration device. According to another aspect, the environmental simulation calibration circuit element 110 changes the output current to one of two values according to at least two set state values.

[0016] In the illustrated embodiment, the variable resistor 110 included in the environmental simulation calibration circuit element 110 can be set to one of three resistance values according to the set state value. Figure 2 A configuration of the environmental simulation calibration circuit element 110 according to an embodiment is illustrated. As shown, the environmental simulation calibration circuit element 110 according to an embodiment includes three resistors R1, R2, and R3 connected in series and switches 112 and 114 for connecting and disconnecting the resistors R2 and R3. The switches 112 and 114 can be configured as, for example, FET elements.

[0017] When all of the switches 112 and 114 are on, the environmental simulation calibration circuit element 110 has the resistance value of R1. This resistance value is designed to output a current value that is obtained when the temperature sensing circuit 130 is exposed to a high temperature (e.g., 90°C) with both resistors R1 and R2 connected, and when the temperature sensing circuit 130 is exposed to room temperature (e.g., 23.5°C) with only the resistor R1 connected. When all of the switches 112 and 114 are off, the environmental simulation calibration circuit element 110 has a value obtained by summing the resistance values of the three resistors R1, R2, and R3. In this case, the resistance value of R3 added is designed to output a current value that is obtained when the temperature sensing circuit 130 is exposed to a low temperature (e.g., -40°C) with both resistors R1 and R2 connected, and when the temperature sensing circuit 130 is exposed to room temperature (e.g., 23.5°C) with all of the three resistors R1, R2, and R3 connected. When the switch 114 is on, the environmental simulation calibration circuit element 110 has a resistance value obtained by adding the resistance values of R1 and R2. In the illustrated embodiment, the environmental simulation calibration circuit element is implemented as a resistance element. However, the proposed invention is not limited thereto and can be implemented as a capacitance element or an inductance element.

[0018] Figure 3is a flowchart showing a configuration of an embodiment of a method of simulating calibration of a circuit element of a design environment. First, one resistor corresponding to a constant amplitude, here R1+R2, is connected to a temperature sensing circuit (step S310). Even if the individual resistance values of R1 and R2 are not determined, the resistance value corresponding to their sum can be set appropriately. Thereafter, the output current is measured at each of a high temperature and a low temperature (step S330). Here, the high temperature is 90°C, and the low temperature is -40°C. In a factory calibration device, a temperature setter 300 can be in contact with the temperature sensing circuit 130, and set its temperature according to a control instruction of a calibration processor.

[0019] Thereafter, when the temperature sensing circuit is exposed to room temperature of 23.5°C, the resistance value at which the output current value measured at the high temperature in step S330 is output is determined as the value of R1 (step S350). Thereafter, when the temperature sensing circuit is exposed to room temperature of 23.5°C, the resistance value at which the output current value measured at the low temperature in step S330 is output is determined, and the value of R3 is determined by subtracting R1+R2 from this resistance value (step S370). These resistance values can be designed by circuit simulation of a design tool, without constructing an actual circuit.

[0020] The measurement value calibration circuit 150 calibrates the output of the temperature sensing circuit 130 according to calibration information set from an external calibration device at the time of factory calibration and outputs. Generally, the output of the temperature sensing circuit deviates from the designed characteristics due to process variation, and factory calibration is performed for its calibration. The error from the temperature-current value characteristics of the design is modeled as an offset and a slope in two-point calibration.

[0021] In an embodiment shown according to a further aspect, the measurement value calibration circuit 150 includes an A / D converter 151 and an adder 155. The A / D converter 151 converts the analog output of the temperature sensing circuit to a digital output. The adder 155 adds a set calibration value to the digital output of the A / D converter 151 and outputs the result. In an embodiment, the calibration value can be a constant value independent of the output of the A / D converter 151. Such a constant can be set in a fuse circuit or an OTP (One Time Programmable) memory. In another embodiment, the calibration value can vary according to the output value of the A / D converter 151. In this case, a calibration value memory 157 can be provided to store a lookup table. As is known, the lookup table can be configured as a memory that uses the output value of the A / D converter 151 as an address and outputs the calibration output value stored at that address.

[0022] According to another aspect, the measurement value calibration circuit 150 can further include a conversion setter 153. The conversion setter 153 sets the offset and gain values of the A / D converter 151 according to calibration information set from an external calibration device during factory calibration. The A / D converter 151 includes an offset addition circuit and a preamplifier circuit that normalize an input signal according to an input range to utilize resolution sufficiently. The external calibration device measures the output current of the temperature sensing circuit 130 while changing temperature to measure the range of output values and the offset in a temperature range specified in a specification, and sets the offset and gain values of the A / D converter according to the measured offset and range. However, since the offset and gain values according to temperature can be non-linear, an adder 155 can be included to additionally apply a calibration value determined according to the output value.

[0023] Figure 4 An embodiment of a temperature sensing circuit according to the proposed application is shown. Figure 1 The shown temperature sensing circuit is merely a typical PTAT circuit to which an environmental simulation calibration circuit element 110 is added according to one aspect of the proposed application. In the shown embodiment, the temperature sensing circuit includes a first constant current circuit 131, a first BJT diode Ql, a second constant current circuit 133, a second BJT diode Q2, and a comparison circuit 132. The output current nlo of the first constant current circuit 131 is set to n times the output current lo of the second constant current circuit 133. The output of the first constant current circuit 131 is provided to the collector of the first BJT diode Ql. The output of the second constant current circuit 133 is provided to the collector of the second BJT diode Q2. The comparison circuit 132 outputs the differential voltage between the input terminal voltage of the first BJT diode Ql and the input terminal voltage of the second BJT diode Q2.

[0024] In this typical PTAT circuit, the voltage difference between the base terminals of the two BJT diodes Ql and Q2 can be expressed as follows.

[0025]

[0026] Here, it is satisfied that Thus, it can be seen that the voltage difference between the base terminals of the two BJT diodes Ql and Q2 is proportional to temperature.

[0027] According to one aspect of the proposed application, the temperature measurement circuit further includes an environmental simulation calibration circuit element. In the shown embodiment, the environmental simulation calibration circuit element 110 includes a variable resistor VR. According to one aspect, the variable resistor VR changes the output current to one of two values according to at least two setting state values. Figure 2 The shown circuit can be Figure 4one possible embodiment of the variable resistor VR. By adjusting the variable resistance, the voltage output at high and low temperature environments can be checked at room temperature environment. When the variable resistor VR is changed substantially, the base voltage of Q1 increases, the collector voltage decreases, and the output of the comparison circuit 132 decreases accordingly. The temperature sensing circuit shown uses the output of the comparator as the output of the circuit. However, a CMOS amplifier circuit with a base connected to the constant current circuits 131 and 133 can be added to the output terminal.

[0028] The proposed invention has been described using a PTAT circuit as an example. However, the same principle can be applied to a CTAT circuit.

[0029] <Description of method invention- Figure 5 <Embodiment> In the following, the invention related to a method of calibrating a temperature measurement circuit will be described. According to one aspect, a temperature measurement circuit to which the presented calibration method is applied can comprise a temperature sensing circuit, an environmental simulation calibration circuit element connected to the temperature sensing circuit to change the output current of the temperature sensing circuit according to an input setting state value, and a measurement value calibration circuit to calibrate the output of the temperature sensing circuit according to a set calibration information and to output. For example, the presented calibration method can be implemented using program instructions executed in a calibration device connected to the above-mentioned temperature measurement circuit to calibrate the circuit. The calibration device can comprise a computing element, such as a microprocessor, and a memory element to store programs and data. According to one aspect, the temperature measurement circuit to be calibrated is kept at a constant temperature (e.g. room temperature) during the calibration operation.

[0030] Figure 5 is a flow chart illustrating a configuration of a method of calibrating a temperature measurement circuit according to an embodiment. As shown, the method of calibrating a temperature measurement circuit according to an embodiment comprises a second calibration information generating step (S550) and a second calibration information setting step (S560). In the embodiment shown, the second calibration information generating step (S550) comprises a first environmental simulation setting step (S551), a first simulation output obtaining step (S553), a calibration information calculating step (S559), and the second calibration information setting step (S560). In the first environmental simulation setting step (S551), the calibration device outputs a first setting state value corresponding to a first temperature to the environmental simulation calibration circuit element. Then, in the first simulation output obtaining step (S553), the calibration device obtains a first output value of the temperature measurement circuit set to the first setting state. The output value of the temperature measurement circuit is the output value of the A / D converter 151 in the embodiment shown, and thus a digital code value. Then, in the calibration information calculating step (S559), the calibration device generates a second calibration information from the first output value. Figure 1 is a flow chart illustrating a configuration of a method of calibrating a temperature measurement circuit according to an embodiment. As shown, the method of calibrating a temperature measurement circuit according to an embodiment comprises a second calibration information generating step (S550) and a second calibration information setting step (S560). In the embodiment shown, the second calibration information generating step (S550) comprises a first environmental simulation setting step (S551), a first simulation output obtaining step (S553), a calibration information calculating step (S559), and the second calibration information setting step (S560). In the first environmental simulation setting step (S551), the calibration device outputs a first setting state value corresponding to a first temperature to the environmental simulation calibration circuit element. Then, in the first simulation output obtaining step (S553), the calibration device obtains a first output value of the temperature measurement circuit set to the first setting state. The output value of the temperature measurement circuit is the output value of the A / D converter 151 in the embodiment shown, and thus a digital code value. Then, in the calibration information calculating step (S559), the calibration device generates a second calibration information from the first output value.

[0031] According to a further aspect, the method of calibrating a temperature measurement circuit according to embodiments (here, in this embodiment, the second calibration information generating step (S550)) can further comprise a second environment simulation setting step (S555) and a second simulated output obtaining step (S557). In the second environment simulation setting step (S555), the calibration device outputs a second setting state value corresponding to a second temperature to the environment simulation calibration circuit element. Then, in the second simulated output obtaining step (S557), the calibration device obtains a second output value of the temperature measurement circuit set to the second setting state. Similar to the first output value, the second output value is a digital code value. Then, in the calibration information calculating step (S559), the calibration device further generates second calibration information from the first output value and the second output value.

[0032] In embodiments, the first temperature can be a high temperature (e.g., 90 °C), and the calibration device outputs a first setting state value for setting the environment simulation calibration circuit element such that the current value output when the temperature measurement circuit as a calibration target is exposed to the high temperature is output at room temperature (e.g., 23.5 °C) corresponding to the current test environment. In embodiments, the second temperature can be a low temperature (e.g., -40 °C), and the calibration device outputs a second setting state value for setting the environment simulation calibration circuit element such that the current value output when the temperature measurement circuit as a calibration target is exposed to the low temperature is output at room temperature corresponding to the current test environment.

[0033] According to a further aspect, the method of calibrating a temperature measurement circuit can further comprise a one-point calibration to calibrate the offset before the two-point calibration. According to this aspect, the temperature measurement circuit to be calibrated is set to room temperature, in this embodiment, to 23.5 °C (step S510). The setting of the room temperature can be achieved by configuring the test chamber as a constant temperature chamber and keeping the temperature constant throughout the chamber. Alternatively, as shown in FIG. 3, the setting of the room temperature can be achieved using a device that comes into contact with the upper surface of the temperature measurement circuit through the temperature setter 300. According to one aspect, when the calibration method according to the proposed invention is in progress, the environment of the temperature measurement circuit as a calibration target is controlled such that the constant temperature set is maintained. Figure 1

[0034] ​Then, the calibration device acquires an output value of the temperature measurement circuit at a set room temperature (step S520). Similar to the first and second output values, the output value at this time is a digital code value. The calibration device generates one-point calibration information from the acquired room temperature output value (step S530). The one-point calibration information can be an offset value of the temperature measurement circuit. Then, the calibration device outputs the generated one-point calibration information to the measurement value calibration circuit of the temperature measurement circuit, and permanently records the one-point calibration information (step S540). For example, the offset can be set by a conversion setter 153 of the A / D converter 151 input to the temperature measurement circuit as a set parameter. Figure 1 As another example, the one-point calibration information can be reflected by recording a generally constant value in the calibration value memory. In this case, the calibration information calculated in step S559 can be recorded by adding to these one-point calibration information values.

[0035] <Description of the method invention> Figure 6 Figure 6 is a flowchart showing a configuration of a method of calibrating a temperature measurement circuit according to another embodiment. Compared to the embodiment of Figure 5 , the embodiment of Figure 6 does not include the step S530 of generating one-point calibration information and the step S540 of setting one-point calibration information. That is, in the illustrated embodiment, the calibration information is generated in step S559 from the output value acquired at the room temperature in step S520, the first analog output value acquired in step S553, and the second analog output value acquired in step S557.

[0036] <Description of the method invention - generation of calibration information> Hereinafter, the process of generating calibration information will be described in detail. The offset value generated in step S530 can be calculated as a difference between a digital output value of a temperature measurement circuit ideally manufactured at a room temperature and a digital output value of the temperature measurement circuit as a calibration target at the room temperature. When the output of the temperature sensing circuit is digitized by an 8-bit A / D converter in the range of -40°C to 87.5°C, the output of the A / D converter at the room temperature 23.5°C is FT TARG = (OTP FT + 40) / 0.5 = (23.5 + 40) / 0.5 = 127.

[0037] Therefore, when the digital output value at the room temperature of the temperature measurement circuit as a calibration target is set to OTP FT DATA, the offset value OFFSET can be obtained as OFFSET = OTP FT DATA - FT TARG = OTP FT DATA - 127.

[0038] ​The output of the temperature measuring circuit needs to be output as a temperature value, not as a number in the range of 0 to 255, so it is necessary to output by adding a certain value to the output value of the A / D converter 151 by the adder 155 Figure 1 When the value of the temperature T expressed in 8 bits within the measurement range of the temperature measuring circuit (-40°C to 87.5°C) is set as TEMP[7:0][T], the digital temperature output value OFFSET_CAL[T] reflecting the offset of the temperature T can be obtained as follows.

[0039] OFFSET_CAL[T] = TEMP[7:0][T] - OFFSET That is, the offset is obtained for all temperature values.

[0040] Next, when the digital output value in the case of the high-temperature environment of the temperature measuring circuit as the calibration target obtained in step S553 is set as OTP_HT_DATA, the digital output value in the case of the low-temperature environment obtained in step S557 is set as OTP_LT_DATA, the high temperature is set as OTP_HT, and the low temperature is set as OTP_LT, the slope of the output of the temperature measuring circuit obtained by the two-point calibration can be obtained as follows.

[0041]

[0042] SLOPE_CAL, the value of the slope of the output value of the A / D converter, that is, the value obtained by applying the slope calibration to the output value of the A / D converter subjected to the offset calibration, can be obtained as follows.

[0043]

[0044] When the code value FT_TARG to be output at room temperature is subtracted from the output value of the A / D converter subjected to the offset calibration, the resulting value is multiplied by 2, then divided by the slope, then FT_TARG is added thereto, the resulting value obtained by performing the offset and slope calibration on the output of the A / D converter is obtained.

[0045] Therefore, the temperature value as the output of the temperature measuring circuit, that is, the value TEMP obtained by converting the output of the A / D converter to the actual temperature value, can be obtained as follows.

[0046]

[0047] When the value of the above calculation is stored at an address corresponding to the temperature T in the calibration value memory 157 of the measurement value calibration circuit 150 in Figure 1 The output of the A / D converter 151 of the temperature sensing circuit 130 can be subjected to two-point calibration and output.

[0048] Statistically, as a result of calibrating 9000 temperature sensors in a temperature range of -40°C to 90°C by applying the calibration method according to the proposed application, an accuracy of approximately 2 code values, i.e. within approximately 1°C, can be obtained based on 8-bit A / D conversion.

[0049] According to the proposed application, a temperature measurement circuit having an accuracy equivalent to two-point calibration is realized without setting an external temperature. Therefore, manufacturing costs can be reduced by adding a simple circuit to the temperature measurement circuit. In addition, since calibration is performed at a constant room temperature, the time required for the calibration operation due to temperature changes can be eliminated, thereby shortening the calibration time.

[0050] Although the present application has been described above with reference to the drawings, the present application is not limited thereto and should be interpreted to encompass various modifications that can be readily derived by those skilled in the art. The claims are intended to cover such modifications.

Claims

1. A temperature measurement circuit comprising: a temperature sensing circuit having a characteristic that varies with temperature; an environment simulation calibration circuit element connected to the temperature sensing circuit to change an output current of the temperature sensing circuit according to a set state value input from an external calibration device during factory calibration; and a measurement value calibration circuit configured to calibrate an output of the temperature sensing circuit and output according to calibration information set from the external calibration device during factory calibration. The environment simulation calibration circuit element changes the output current to one of two values according to at least two set state values.

2. The temperature measurement circuit of claim 1, wherein, The measurement value calibration circuit includes:

3. The temperature measurement circuit of claim 1, wherein, an analog-digital converter configured to convert an analog output of the temperature sensing circuit to a digital output; and a summer configured to add a set calibration value to the digital output of the analog-digital converter and output a result value. The measurement value calibration circuit further includes a conversion setter configured to set an offset and a gain of the analog-digital converter according to calibration information set from the external calibration device during factory calibration.

4. The temperature measurement circuit of claim 3, wherein, The temperature sensing circuit includes a bipolar junction transistor diode to which a constant current is supplied at an input terminal of the bipolar junction transistor diode.

5. The temperature measurement circuit of claim 1, wherein, The environment simulation calibration circuit element includes a variable resistor having one end connected to an output terminal of the bipolar junction transistor diode and having different resistance values depending on at least two set state values input from an external controller during factory calibration.

6. The temperature measurement circuit of claim 5, wherein, The temperature sensing circuit includes:

7. The temperature measurement circuit of claim 5, wherein, a first constant current circuit; a first bipolar junction transistor diode having a collector to which an output of the first constant current circuit is supplied; a second constant current circuit; a second bipolar junction transistor diode having a collector to which an output of the second constant current circuit is supplied; and a comparison circuit configured to output a voltage difference between an input terminal voltage of the first bipolar junction transistor diode and an input terminal voltage of the second bipolar junction transistor diode. The environment simulation calibration circuit element includes a variable resistor having one end connected to an output terminal of the first bipolar junction transistor diode and having different resistance values depending on at least two set state values input from an external controller during factory calibration.

8. The temperature measurement circuit of claim 7, wherein, 9. A method of calibrating a temperature measurement circuit, the method performed by a calibration device configured to calibrate the temperature measurement circuit, the temperature measurement circuit including a temperature sensing circuit, an environment simulation calibration circuit element connected to the temperature sensing circuit to change an output current of the temperature sensing circuit according to a set state value, and a measurement value calibration circuit configured to calibrate an output of the temperature sensing circuit and output according to a set calibration information, the method comprising: a first environment simulation setting step of outputting a first set state value corresponding to a first temperature to the environment simulation calibration circuit element; ​ a first analog output acquisition step for acquiring a first output value of the temperature measuring circuit; a second calibration information generation step for generating second calibration information from the first output value; and a second calibration information setting step for outputting the second calibration information to a measurement value calibration circuit of the temperature measuring circuit and permanently recording the second calibration information.

10. The method of claim 9, wherein, Between the first analog output acquisition step and the second calibration information generation step, the method further comprises: a second environmental simulation setting step for outputting a second setting state value corresponding to a second temperature to the environmental simulation calibration circuit element; and a second analog output acquisition step for acquiring a second output value of the temperature measuring circuit, and the second calibration information generation step comprises generating second calibration information from the first output value and the second output value.

11. The method of claim 10, wherein, Before the first environmental simulation setting step, the method further comprises: a room temperature setting step for setting the temperature measuring circuit to be calibrated to room temperature; and a room temperature output acquisition step for acquiring a room temperature output value of the temperature measuring circuit at room temperature, and the second calibration information generation step comprises generating second calibration information from the room temperature output value, the first output value and the second output value.

12. The method of claim 9, wherein, Before the first environmental simulation setting step, the method further comprises: a room temperature setting step for setting the temperature measuring circuit to be calibrated to room temperature; a room temperature output acquisition step for acquiring a room temperature output value of the temperature measuring circuit at room temperature; a one-point calibration information generation step for generating one-point calibration information from the acquired room temperature output value; and a one-point calibration information setting step for outputting the one-point calibration information to the measurement value calibration circuit of the temperature measuring circuit and permanently recording the one-point calibration information.

13. The method of claim 9, wherein, The environment is controlled so that the temperature measuring circuit that is the calibration target is kept at a constant temperature while the method is being performed.

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