Temperature sensor and temperature calibration method

Abstract

This disclosure provides a temperature sensor and a temperature calibration method, which can be applied in the field of sensing technology. The method includes: a temperature sensing circuit for determining a nonlinear parameter based on a third adjustable parameter and a temperature coefficient based on a first adjustable parameter; a signal conditioning circuit for determining a zero-degree output parameter based on a second adjustable parameter; and a temperature sensor for determining a calibration output curve based on the nonlinear parameter, the temperature coefficient, and the zero-degree output parameter; wherein the second and third adjustable parameter signals are parameters of the signal conditioning circuit, the first adjustable parameter is a parameter of the temperature sensing circuit, and the calibration output curve is an output curve that is linearly related to temperature.

Description

Technical Field

[0001] This disclosure relates to the field of sensing technology, and more specifically, to a temperature sensor and a temperature adjustment and calibration method. Background Technology

[0002] With the rapid development of the electronics and information industry, temperature sensors have become one of the most widely used sensor components. Temperature sensor calibration and adjustment technologies have also received widespread attention, leading to increasingly stringent requirements for sensor accuracy. In related technologies, temperature sensors can be based on bipolar junction transistors (BJTs). However, this characteristic of sensing temperature based on absolute temperature can make the sensor's accuracy susceptible to variations in current gain, device mismatch, mechanical stress, and manufacturing processes, resulting in inaccurate temperature measurements. To address this inaccuracy, single-point calibration methods calibrate across the entire temperature range by measuring the temperature error at a single point. This method only achieves good measurement results at the calibrated single-point temperature, sacrificing measurement accuracy across the temperature range beyond that point. Two-point temperature calibration methods improve calibration accuracy by calibrating the temperature coefficient, but this increases calibration time and cost. Summary of the Invention

[0003] In view of this, the present disclosure provides a temperature sensor and a temperature adjustment and calibration method in order to partially solve at least one of the aforementioned technical problems.

[0004] One aspect of this disclosure is a temperature sensor.

[0005] The temperature sensor includes:

[0006] The temperature sensing circuit is used to determine the nonlinear parameter based on the third adjustable parameter and the temperature coefficient based on the first adjustable parameter; the signal conditioning circuit is used to determine the zero-degree output parameter based on the second adjustable parameter; wherein the temperature sensor is used to determine the adjusted output curve based on the nonlinear parameter, the temperature coefficient, and the zero-degree output parameter; wherein the second and third adjustable parameter signals are parameters of the signal conditioning circuit, the first adjustable parameter is a parameter of the temperature sensing circuit, and the adjusted output curve is an output curve that is linearly related to the temperature.

[0007] According to an embodiment of this disclosure, the temperature sensing circuit includes: a first resistor, a first adjustable resistor, a temperature sensing resistor, a second resistor, and a third resistor.

[0008] The first end of the first resistor is connected to the power supply voltage, and the second end is connected to the first end of the first adjustable resistor and the first end of the third resistor; the second end of the first adjustable resistor is connected to the first end of the temperature sensing resistor and the first end of the second resistor; the second end of the temperature sensing resistor is grounded; the second end of the second resistor is connected to the signal conditioning circuit; the second end of the third resistor is connected to the signal conditioning circuit; wherein, the first adjustable parameter is the parameter of the first adjustable resistor.

[0009] According to an embodiment of this disclosure, the signal conditioning circuit includes: a second adjustable resistor, a third adjustable resistor, a fourth resistor, an operational amplifier, and an analog-to-digital converter.

[0010] The first terminal of the second adjustable resistor is connected to the power supply voltage, and the second terminal is connected to the first terminal of the third adjustable resistor, the first terminal of the fourth resistor, and the negative input terminal of the operational amplifier; the second terminal of the third adjustable resistor is grounded; the second terminal of the fourth resistor is connected to the output terminal of the operational amplifier, the input terminal of the analog-to-digital converter, and the second terminal of the third resistor; the positive input terminal of the operational amplifier is connected to the second terminal of the second resistor; the power supply terminal and the reference voltage input terminal of the analog-to-digital converter are connected to the power supply voltage, and the ground terminal is grounded; wherein, the second adjustable parameter is the parameter of the second adjustable resistor, and the third adjustable parameter is the parameter of the third adjustable resistor.

[0011] According to an embodiment of this disclosure, the intersection of the second end of the fourth resistor, the output end of the operational amplifier, the input end of the analog-to-digital converter, and the second end of the third resistor is the output voltage acquisition point of the temperature sensor; the analog-to-digital converter is used to determine the output voltage based on the output voltage acquisition point; and to determine the adjusted output curve based on the reference voltage and the output voltage.

[0012] According to an embodiment of this disclosure, the temperature sensing resistor is composed of a circuit that has temperature information, and the circuit includes elements that have temperature information.

[0013] According to embodiments of this disclosure, the first adjustable resistor, the second adjustable resistor, and the third adjustable resistor are thin-film resistors and / or adjustable resistor arrays composed of resistors and metal fuses.

[0014] According to an embodiment of this disclosure, the temperature sensor further includes an external power supply; the external power supply provides the temperature sensor with the power supply voltage and the reference voltage.

[0015] In another aspect of this disclosure, a temperature adjustment and calibration method for a temperature sensor according to any of the above claims is provided, comprising:

[0016] A nonlinear parameter is determined based on the second and third adjustable parameters; if the nonlinear parameter meets a preset condition, a temperature coefficient is determined based on the first adjustable parameter; if the temperature coefficient meets a preset condition, a zero-degree output parameter is determined based on the second adjustable parameter; if the zero-degree output parameter meets a preset condition, the calibration of the temperature sensor is completed; wherein the second adjustable parameter, the third adjustable parameter, and the zero-degree output parameter are parameters of the signal conditioning circuit, and the nonlinear parameter, the temperature coefficient, and the first adjustable parameter are parameters of the temperature sensing circuit.

[0017] According to an embodiment of this disclosure, the temperature sensing circuit includes a first adjustable resistor; the signal conditioning circuit includes a second adjustable resistor and a third adjustable resistor; the first adjustable parameter is adjusted by adjusting the resistance value of the first adjustable resistor; the second adjustable parameter is adjusted by adjusting the resistance value of the second adjustable resistor; and the third adjustable parameter is adjusted by adjusting the resistance value of the third adjustable resistor.

[0018] According to embodiments of this disclosure, adjusting the resistance values ​​of the first adjustable resistor, the second adjustable resistor, and the third adjustable resistor includes any one of the following methods or a combination of the following methods: discrete adjustment, continuous adjustment, and fuse adjustment.

[0019] According to embodiments of this disclosure, by adjusting the adjustable parameters of the temperature sensing circuit and signal conditioning circuit included in the temperature sensor, the adjusted nonlinear parameters, zero-degree output parameters, and zero-degree output parameters are obtained, eliminating the influence of temperature on the temperature sensor's temperature sensing capability during the adjustment process. The temperature sensor circuit structure is simple and easy to implement, and is unaffected by power fluctuations. It can realize automated adjustment algorithms, achieving high calibration accuracy and short adjustment time. Based on the above technical means, at least partially overcoming the technical problem that related technologies cannot adequately guarantee the efficiency and accuracy of temperature calibration under arbitrary external temperatures, thereby improving the efficiency and accuracy of temperature calibration. Attached Figure Description

[0020] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 The schematic diagram illustrates the circuit structure of a temperature sensor in the relevant technology.

[0022] Figure 2 A flowchart illustrating a single-point temperature calibration method of the relevant technology is shown.

[0023] Figure 3 A schematic block diagram of a temperature sensor according to an embodiment of the present disclosure is shown.

[0024] Figure 4 A schematic block diagram of a temperature sensor according to another embodiment of the present disclosure is shown.

[0025] Figure 5 A flowchart illustrating a temperature adjustment and calibration method according to an embodiment of the present disclosure is shown schematically.

[0026] Figure 6 An initial output curve of an unadjusted temperature sensor according to an embodiment of the present disclosure is illustrated schematically.

[0027] Figure 7 The diagram illustrates the output curve after calibrating the nonlinear parameters according to an embodiment of the present disclosure.

[0028] Figure 8 The diagram schematically illustrates the output curve after calibrating the temperature coefficient according to an embodiment of the present disclosure.

[0029] Figure 9 The diagram illustrates the output curve after calibrating the zero-degree output parameters according to an embodiment of the present disclosure. Detailed Implementation

[0030] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0032] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0033] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). Similarly, when using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0034] Temperature sensors can provide temperature information in a readable form via electrical signals.

[0035] Figure 1 The schematic diagram illustrates the circuit structure of a temperature sensor in the relevant technology.

[0036] like Figure 1 As shown, the temperature sensor 100 of the related technology may include: a first transistor 1, a second transistor 2, a third transistor 3, a first current source 4, a second current source 5, a third current source 6, an operational amplifier 7, and an analog-to-digital converter 8.

[0037] In this configuration, the first terminal of the first transistor 1 is connected to the first current source 4 and the negative input terminal of the operational amplifier 7; the first terminal of the second transistor 2 is connected to the second current source 5 and the positive input terminal of the operational amplifier 7; the first terminal of the third transistor 3 is connected to the second current source 5, and the output of the first terminal of the third transistor 3 is processed together with the output of the operational amplifier 7, and the processed data is input to the analog-to-digital converter 8; the second and third terminals of the first transistor 1, the second and third terminals of the second transistor 2, and the second and third terminals of the second transistor 2 are all grounded; the output terminal of the operational amplifier 7 is connected to the analog-to-digital converter 8; and an output signal is obtained at the output terminal of the analog-to-digital converter 8.

[0038] The temperature sensor 100 senses temperature through a transistor. The first voltage signal ΔV in the temperature sensor 100... BE It can be represented by the following formula (1).

[0039]

[0040] In the formula, ΔV BE It is the first voltage signal positively correlated with T; k is the Boltzmann constant; T is the Kelvin temperature; q is the electron charge; I SI1 is the saturation current; p is the ratio of bias currents; r is the ratio of emitter area.

[0041] The second voltage signal in the temperature sensor 100 can be represented by the following formula (2).

[0042]

[0043] In the formula, V BE I1 is the second voltage signal negatively correlated with T; I2 is the second bias current.

[0044] The first voltage signal is amplified by operational amplifier 7 to obtain the input signal of operational amplifier 7, which can be expressed by the following formula (3): V PTAT .

[0045] V PTAT =α·ΔV BE (3)

[0046] In the formula, α is the amplification factor of operational amplifier 7.

[0047] Based on the first voltage signal and the second voltage signal, the reference signal is obtained as V. REF The reference signal V can be represented by the following formula (4). REF .

[0048] V REF =V BE +α·ΔV BE (4)

[0049] Based on the input signal and the reference signal, the output signal is obtained, which can be expressed by the following formula (5): D out .

[0050]

[0051] However, in actual sensing processes, temperature sensors based on BJT temperature sensing elements have many error sources, V BE and ΔV BE It is affected by various non-ideal factors (such as process errors, curvature, series resistance, finite current gain, etc.). Therefore, the reference signal and input signal will deviate from the ideal values, resulting in temperature measurement errors in the output signal.

[0052] The corresponding temperature coefficient can be obtained from the output signal, and the temperature coefficient TC can be represented by the following formula (6).

[0053]

[0054] At the set temperature, i.e., the single-point temperature T required by the single-point adjustment and calibration method. cal Then, according to formula (7), V can be obtained. BE The adjustment amount V can be expressed by the following formula (7). BE Adjustment amount V BE,error :

[0055]

[0056] In the formula, V BE,error It is V BE Adjustment amount; V BE1 It is the actual second voltage signal obtained before adjustment; D out1 It is the actual output signal obtained; V BE,ideal It is an ideal second voltage signal; D out1,ideal It is an ideal output signal.

[0057] Figure 2 A flowchart illustrating a single-point temperature calibration method of the relevant technology is shown.

[0058] like Figure 2 As stated, after obtaining V BE In the case of adjustment amount, it can be achieved by adjusting V. BE The system obtains the adjusted output signal; it then determines whether the adjusted output signal meets the temperature measurement error standard. If the adjusted output signal meets the standard, the temperature sensor is adjusted; otherwise, the temperature sensor cannot perform temperature measurement normally.

[0059] In related technologies, a single-point adjustment and calibration method can be used, that is, a resistor can be connected in series at the first terminal of the third transistor 3, and the voltage across the resistor can be adjusted to achieve the calibration of V. BE The adjustment.

[0060] However, although the above-mentioned single-point adjustment calibration method can perfectly calibrate T at a specified ambient temperature, cal While the temperature measurement error is reduced, it does not adequately meet the requirements for calibrating the temperature measurement error across the entire temperature range. Furthermore, this single-point adjustment calibration method does not calibrate the temperature coefficient shown in formula (6), which leads to the sacrifice of temperature measurement error at the end of the temperature range, resulting in low calibration accuracy. Moreover, this adjustment method, which requires a specified ambient temperature, increases calibration costs and introduces calibration errors, resulting in high calibration costs.

[0061] Research and analysis revealed that, compared to the single-source nature of BJT temperature sensing, resistance-based temperature sensing elements result in fewer error sources for temperature sensors. Furthermore, the inherent characteristic of resistance sensing, which is not based on absolute temperature, allows for more flexible and precise adjustment.

[0062] In order to at least partially solve the technical problems existing in the related technologies, this disclosure provides a temperature sensor and a temperature adjustment and calibration method, which can be applied to the field of sensing technology.

[0063] Figure 3 A schematic block diagram of a temperature sensor according to an embodiment of the present disclosure is shown.

[0064] like Figure 3 As shown, the temperature sensor 300 includes a temperature sensing circuit 310 and a signal conditioning circuit 320.

[0065] The temperature sensing circuit 310 is used to determine the nonlinear parameter based on the third adjustable parameter and to determine the temperature coefficient based on the first adjustable parameter.

[0066] The signal conditioning circuit 320 is used to determine the zero-degree output parameter based on the second adjustable parameter. The temperature sensor can be used to determine the adjusted output curve based on the nonlinear parameter, temperature coefficient, and zero-degree output parameter. The second and third adjustable parameter signals are parameters of the signal conditioning circuit, the first adjustable parameter is a parameter of the temperature sensing circuit, and the adjusted output curve is an output curve that has a linear relationship with temperature.

[0067] According to an embodiment of this disclosure, the temperature sensing circuit 310 can sense the external temperature through the temperature sensing element inside the circuit, and then output a voltage signal with temperature information to the signal conditioning circuit 320.

[0068] According to embodiments of this disclosure, the signal conditioning circuit 320 may include an operational amplifier and an analog-to-digital converter to amplify the voltage signal of the temperature sensing circuit 310. The signal conditioning circuit 320 may also include multiple resistive elements to enable the normal functioning of the temperature sensor 300 circuit. An adjusted output curve is then output externally.

[0069] According to the embodiments of this disclosure, the resistive element may have resistance value errors. These resistance errors can be one of the error sources in the temperature sensor circuit, as well as non-ideal factors in the operational amplifier, such as offset voltage and bias current. These error sources mainly affect the accuracy of the temperature sensor in the following three aspects: 1. They affect the linearity of the temperature sensor 300; 2. They affect the accuracy of the temperature coefficient of the temperature sensor 300; 3. They affect the accuracy of the zero-degree output of the temperature sensor 300.

[0070] According to embodiments of this disclosure, linearity characterizes the consistency of the output curve of the temperature sensor 300 within a certain temperature range. The temperature coefficient characterizes the slope of the output curve of the temperature sensor 300 as a function of temperature. Zero-degree output refers to the signal value corresponding to the output curve of the temperature sensor 300 at 0°C.

[0071] According to the embodiments of this disclosure, a temperature sensing element is used to sense temperature, a signal conditioning circuit 320 is used to process the temperature-related voltage signal, and the parameters of the circuit elements of the temperature sensing circuit 310 and the signal conditioning circuit 320 can be adjusted to achieve the adjustment and calibration of the three indicators of the temperature sensor—nonlinearity, temperature coefficient, and zero-degree output—at any ambient temperature through a single-point temperature adjustment and calibration method.

[0072] According to embodiments of this disclosure, the single-point temperature adjustment calibration method is a method of adjusting the circuit component parameters of the temperature sensor 300 at a specific temperature point to achieve full-temperature-range error adjustment calibration.

[0073] According to embodiments of this disclosure, by adjusting the adjustable parameters of the temperature sensing circuit and signal conditioning circuit included in the temperature sensor, the adjusted nonlinear parameters, temperature coefficient, and zero-degree output parameters are obtained, eliminating the influence of temperature on the temperature sensor's sensing capability during the adjustment process. The temperature sensor circuit structure is simple and easy to implement, and is unaffected by power fluctuations. It can realize automated calibration algorithms, achieving high calibration accuracy and short calibration time. Based on the above technical means, at least partially overcoming the technical problem that related technologies cannot adequately guarantee the efficiency and accuracy of temperature calibration under arbitrary external temperatures, thereby improving the efficiency and accuracy of temperature calibration.

[0074] According to an embodiment of this disclosure, the temperature sensor 300 can also be connected to an external power supply; the external power supply provides a power supply voltage and a reference voltage to the temperature sensor so that the circuit of the temperature sensor 300 can perform sensing normally.

[0075] Figure 4 A schematic block diagram of a temperature sensor according to another embodiment of the present disclosure is shown.

[0076] like Figure 4 As shown, the temperature sensing circuit 310 may include: a first resistor R1, a first adjustable resistor R2, a temperature sensing resistor RT, a second resistor R5, and a third resistor R6.

[0077] The first terminal of the first resistor R1 is connected to the power supply voltage, and the second terminal is connected to the first terminals of the first adjustable resistor R2 and the third resistor R6. The second terminal of the first adjustable resistor R2 is connected to the first terminal of the temperature sensing resistor RT and the first terminal of the second resistor R5. The second terminal of the temperature sensing resistor RT is grounded. The second terminal of the second resistor R5 is connected to the signal conditioning circuit. The second terminal of the third resistor R6 is connected to the signal conditioning circuit. The first adjustable parameter is the parameter of the first adjustable resistor R2.

[0078] like Figure 4As shown, the signal conditioning circuit 320 includes: a second adjustable resistor R3, a third adjustable resistor R4, a fourth resistor RF, an operational amplifier OP, and an analog-to-digital converter ADC.

[0079] The first terminal of the second adjustable resistor R3 is connected to the power supply voltage, and the second terminal is connected to the first terminal of the third adjustable resistor R4, the first terminal of the fourth resistor RF, and the negative input terminal of the operational amplifier OP. The second terminal of the third adjustable resistor R4 is grounded. The second terminal of the fourth resistor RF is connected to the output terminal of the operational amplifier OP, the input terminal of the analog-to-digital converter ADC, and the second terminal of the third resistor R6. The positive input terminal of the operational amplifier OP is connected to the second terminal of the second resistor R5. The power supply terminal and reference voltage input terminal of the analog-to-digital converter ADC are connected to the power supply voltage, and the ground terminal is grounded. The second adjustable parameter is the parameter of the second adjustable resistor R3, and the third adjustable parameter is the parameter of the third adjustable resistor R4.

[0080] According to the embodiments of this disclosure, the resistance value of the temperature sensing resistor RT can change according to the external temperature change in the presence of a constant current source. Thus, the temperature sensing circuit 310 can output a voltage signal with temperature information when the power supply voltage is obtained from the first resistor R1.

[0081] According to embodiments of this disclosure, the temperature-sensing resistor RT can be constructed from a circuit that provides temperature information. The circuit includes a first terminal connected to the second terminal of a first adjustable resistor R2 and the first terminal of a second resistor R5, and a second terminal grounded. The circuit providing temperature information can be a complex circuit with multiple components or a simple circuit with one or two components. Those skilled in the art can select a temperature-sensing circuit that includes temperature-sensing elements and specific connection relationships according to actual needs, and no limitation is made here.

[0082] According to embodiments of this disclosure, the temperature-sensing resistor RT can also be directly composed of an element with temperature information. The temperature-sensing element includes a first terminal connected to the second terminal of the first adjustable resistor R2 and the first terminal of the second resistor R5, and a second terminal grounded. Those skilled in the art can select the corresponding type of temperature-sensing element according to actual needs, and no limitation is made here.

[0083] According to embodiments of this disclosure, the temperature sensing resistor RT can also be directly composed of a temperature sensing resistor. The resistance types and characteristics of common temperature sensing resistors used in integrated circuits are shown in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087] According to embodiments of this disclosure, based on the resistance types and characteristics shown in Table 1 and the actual temperature sensing requirements of the temperature sensor 300, the temperature sensing resistor RT can be selected as a metal resistor or an S-Poly resistor. Those skilled in the art can also select corresponding types of temperature sensing resistors according to other actual needs, which are not limited here.

[0088] According to embodiments of this disclosure, in a temperature sensing circuit, it is not only necessary to use a temperature-sensing resistor to sense the external temperature in order to obtain a voltage signal, but also to ensure that the temperature-sensing resistor has low power supply sensitivity, noise, and stress sensitivity, thereby reducing the component noise introduced by the temperature-sensing resistor element into the circuit and improving the signal quality of the voltage signal.

[0089] According to embodiments of this disclosure, the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 can be thin-film resistors. Thin-film resistors are made by depositing a material of a certain resistivity onto the surface of an insulating material using a method similar to evaporation. The resistance value of the thin-film resistor can be changed by altering the thickness of the thin-film material connected to the circuit. Changes in the resistance value of a thin-film resistor are generally irreversible.

[0090] According to embodiments of this disclosure, CrSi thin-film resistors can be selected as the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4, as CrSi thin-film resistors have a low temperature coefficient. Those skilled in the art can also select corresponding types of thin-film resistors according to other practical needs, and no limitation is made here.

[0091] According to embodiments of this disclosure, the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 can also be an adjustable resistor array composed of resistors and metal fuses. The resistance values ​​of the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 can be adjusted by adjusting the metal fuses, and the change in resistance value is generally irreversible.

[0092] According to an embodiment of this disclosure, in one embodiment, the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 may be of the same type or different types. Those skilled in the art can choose according to actual needs, and no limitation is made here.

[0093] According to an embodiment of this disclosure, the first adjustable parameter is the parameter of the first adjustable resistor R2, that is, the resistance value of the first adjustable resistor R2; the second adjustable parameter is the parameter of the second adjustable resistor R3, that is, the resistance value of the second adjustable resistor R3; and the third adjustable parameter is the parameter of the third adjustable resistor R4, that is, the resistance value of the third adjustable resistor R4.

[0094] According to the embodiments of this disclosure, the first resistor R1, the second resistor R5, the third resistor R6, and the fourth resistor RF are ordinary resistors, whose resistance values ​​are fixed in the circuit and generally do not change. The first resistor R1, the second resistor R5, the third resistor R6, and the fourth resistor RF can be poly resistors or diff resistors. Those skilled in the art can also select corresponding types of resistors according to other practical needs, and this is not limited thereto.

[0095] According to the embodiments of this disclosure, by adjusting the resistance values ​​of the third adjustable resistor R4, the first adjustable resistor R2, and the second adjustable resistor R3 in a preset order, the calibration of three indicators of the temperature sensor—nonlinearity, temperature coefficient, and zero-degree output—can be achieved at any ambient temperature.

[0096] According to the embodiments of this disclosure, the temperature sensing resistor RT needs to operate in the presence of a constant current source in the temperature sensing circuit 310. This constant current source can be formed by a positive feedback loop consisting of a first resistor R1, a first adjustable resistor R2, and a second resistor R5 in the circuit. The positive feedback loop makes the voltage of the current flowing through the first adjustable resistor R2 independent of the temperature, thereby approximating a constant current source.

[0097] According to an embodiment of this disclosure, the current flowing through the first adjustable resistor R2 can be represented by the following formula (8).

[0098]

[0099] In the formula, Vcc is the power supply voltage; I R2 R1 is the current flowing through the first adjustable resistor R2; R2 is the resistance of the first adjustable resistor R2; R3 is the resistance of the second adjustable resistor R3; R4 is the resistance of the first adjustable resistor R1; R5 is the resistance of the second adjustable resistor R5; R F This is the resistance value of the fourth resistor RF; R T It is the resistance value of the temperature sensing resistor RT.

[0100] According to the embodiments of this disclosure, it can be obtained from formula (8) that R in the denominator T The coefficient part is designed to be 0, that is... When I is designed to be 0, R2 Regarding R T The value is independent of the current, thus the current flowing through the first adjustable resistor R2 is a constant current source, which is proportional to the power supply voltage Vcc and independent of temperature.

[0101] According to the embodiments of this disclosure, when the coefficient part of RT is 0 and the non-ideal characteristics of the operational amplifier OP, such as the bias current, are not considered, R5 is designed to be much larger than R1 and R2. The voltage value of the temperature sensing resistor RT, that is, the output value of the temperature sensing circuit 310, can be obtained based on formula (8) and simplified. The voltage value of the temperature sensing resistor RT can be expressed by the following formula (9).

[0102]

[0103] In the formula, V RT It is the voltage value of the temperature sensing resistor RT; R T0 TC is the resistance value of the temperature sensing resistor RT at the actual sensing temperature; TFR It is the temperature coefficient of the temperature sensing resistor; T A It is any non-fixed ambient temperature under actual sensing conditions.

[0104] According to embodiments of this disclosure, in actual sensing, V RT The value is relatively small; if V is processed directly through a temperature sensor interface circuit or an ADC... RT Obtaining a sensing curve showing a linear relationship with temperature places very high demands on the temperature sensor interface circuit or ADC, which is not conducive to practical sensing applications. Therefore, it is also necessary to further refine the V... RT Modular-to-digital conversion can only be performed after conditioning.

[0105] According to an embodiment of this disclosure, the operational amplifier OP of the signal conditioning circuit 320 can be a non-inverting operational amplifier with DC bias. Through the operational amplifier OP and the analog-to-digital converter ADC, V can be... RT The voltage value is amplified. Simultaneously, the operational amplifier (OP) and analog-to-digital converter (ADC) can amplify the temperature coefficient of the temperature sensor 300, thereby improving the accuracy of the temperature sensor 300.

[0106] like Figure 4 As shown, the intersection of the second end of the fourth resistor RF, the output end of the operational amplifier OP, the input end of the analog-to-digital converter ADC, and the second end of the third resistor R6 can be set as the output voltage acquisition point of the temperature sensor.

[0107] According to the embodiments of this disclosure, when the operational amplifier OP is an ideal operational amplifier, the output voltage amplified by the operational amplifier OP can be obtained at the output voltage acquisition point according to formula (9), and the output voltage can be expressed by the following formula (10).

[0108]

[0109] In the formula, V out It is the output voltage.

[0110] According to the embodiments of this disclosure, it can be obtained from formula (10) that the output voltage is linearly related to the temperature and is proportional to the power supply voltage.

[0111] According to embodiments of this disclosure, an analog-to-digital converter (ADC) can determine the ratio of the output voltage to the reference voltage provided by the external power supply based on the output voltage and the reference voltage provided by the external power supply, thereby determining the adjusted output curve. The adjusted output curve can be represented by the following formula (11).

[0112]

[0113] In the formula, D out It's about adjusting the output curve; V ref It is the reference voltage, which can be the voltage provided by an external power source to the temperature sensor.

[0114] According to the embodiments of this disclosure, it can be obtained from formula (11) that the adjusted output curve is linearly related to the temperature and is independent of the power supply voltage.

[0115] According to embodiments of this disclosure, by designing the circuit structure of the temperature sensor 300, including the temperature sensing circuit 310 and the signal conditioning circuit 320, and designing a single-point calibration method, temperature is sensed using resistance, the temperature-related voltage signal is processed using the signal conditioning circuit, and the single-point temperature calibration method is used to calibrate the nonlinearity, temperature coefficient, and zero-degree output of the temperature sensor at any ambient temperature. Compared with the prior art, the circuit structure of this disclosure is simple, the calibration algorithm is easy to implement, the calibration cost is low, and the calibration accuracy is high.

[0116] Figure 5 A flowchart illustrating a temperature adjustment and calibration method according to an embodiment of the present disclosure is shown schematically.

[0117] like Figure 5 As shown, the temperature adjustment and calibration method for a temperature sensor includes operations S510 to S540.

[0118] In operation S510, the nonlinear parameters are determined based on the second and third adjustable parameters.

[0119] When operating S520, if the nonlinear parameters meet the preset conditions, the temperature coefficient is determined based on the first adjustable parameter.

[0120] When operating S530, if the temperature coefficient meets the preset conditions, the zero-degree output parameter is determined according to the second adjustable parameter.

[0121] When operating the S540, the temperature sensor is calibrated if the zero-degree output parameters meet the preset conditions.

[0122] Among them, the second adjustable parameter, the third adjustable parameter, and the zero-degree output parameter are parameters of the signal conditioning circuit, while the nonlinear parameter, the temperature coefficient, and the first adjustable parameter are parameters of the temperature sensing circuit.

[0123] According to an embodiment of this disclosure, the temperature sensing circuit includes a first adjustable resistor R2. The signal conditioning circuit includes a second adjustable resistor R3 and a third adjustable resistor R4. A first adjustable parameter is adjusted by adjusting the resistance value of the first adjustable resistor R2; a second adjustable parameter is adjusted by adjusting the resistance value of the second adjustable resistor R3; and a third adjustable parameter is adjusted by adjusting the resistance value of the third adjustable resistor R4.

[0124] According to the embodiments of this disclosure, in operation S510, the nonlinear error mainly exists in the constant current source in the temperature sensing circuit 310. It can be found through formula (8) that R shown in the denominator T The term is a nonlinear error term, which means that R... T The coefficients corresponding to the terms are defined as nonlinear parameters, which can be expressed by the following formula (12).

[0125]

[0126] In the formula, k 非线性 It is a nonlinear parameter.

[0127] According to the embodiments of this disclosure, in actual adjustment, such as in actual wafer testing, testing all the parameters included in formula (12) one by one would result in a significant waste of resources and time, and is not suitable for actual temperature adjustment calibration methods. Therefore, formula (12) can be simplified to obtain simpler adjustment parameters related to nonlinear parameters.

[0128] According to embodiments of this disclosure, the simplified nonlinear parameters can be represented by the following formula (13).

[0129]

[0130]

[0131] In the formula, gain is the gain of the signal conditioning circuit 320, and its expression can be represented by formula (13.1).

[0132] According to the embodiments of this disclosure, both the first resistor R1 and the second resistor R5 can be ordinary resistors. After matching design, the ratio of R1 / R5 is less affected by the process and can be directly used with the preset design value. Therefore, in the adjustment test, only the gain value needs to be tested and adjusted to realize the calculation and calibration of nonlinearity. That is, by adjusting the resistance value of the second adjustable resistor R3, the nonlinear parameters that meet the preset conditions can be obtained.

[0133] According to an embodiment of this disclosure, in operation S520, the temperature coefficient of the temperature sensor 300 can be obtained according to formula (10), and the temperature coefficient TC can be expressed by the following formula (14).

[0134]

[0135] According to an embodiment of this disclosure, according to formula (14), when actually adjusting the temperature coefficient, the first adjustable resistor R2 in the denominator can be selected to calibrate the temperature coefficient.

[0136] According to the embodiments of this disclosure, in actual adjustment, the temperature coefficient expressed by formula (14) can be further simplified. According to formula (9) and formula (14), the simplified temperature coefficient can be obtained. The simplified temperature coefficient can be expressed by the following formula (15).

[0137]

[0138] In the formula, V RT It is the voltage of the temperature sensing resistor.

[0139] According to the embodiments of this disclosure, according to formula (15), when actually adjusting the temperature coefficient, the current ambient temperature and the voltage of the temperature sensing resistor under the actual adjustment situation can be obtained, so as to realize the calculation and calibration of the temperature coefficient.

[0140] According to an embodiment of this disclosure, in operation S530, zero-degree output refers to the output signal value of the temperature sensor at 0°C. The zero-degree output expression can be obtained according to formula (10). The zero-degree output V can be expressed by the following formula (16). T0 .

[0141]

[0142] According to the embodiments of this disclosure, according to formula (16), in order to avoid the influence of adjusting R3 on the nonlinearity, R4 should be much smaller than R3 in the design.

[0143] According to the embodiments of this disclosure, when the nonlinear parameters and temperature coefficients both meet the preset conditions, the zero-degree output can be simplified as shown in the following formula (17). In the adjustment test, only the current ambient temperature and output voltage need to be measured to achieve the adjustment of the zero-degree output V. T0 Calculation and calibration.

[0144] V T0 =V out -TCT A (17)

[0145] According to embodiments of this disclosure, adjusting the resistance values ​​of the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 includes any one of the following methods or a combination of the following methods: discrete adjustment, continuous adjustment, and fuse adjustment.

[0146] According to embodiments of this disclosure, the adjustment of the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 may include a discrete adjustment portion and a continuous adjustment portion. The discrete portion typically employs a fuse method, while the continuous portion typically employs a cap-type resistor.

[0147] According to embodiments of this disclosure, a "test-while-adjusting" method can be adopted during the actual adjustment process, stopping the adjustment once the expected effect is achieved. This design ensures both adjustment accuracy and speed.

[0148] Figure 5 A flowchart illustrating a temperature adjustment and calibration method according to an embodiment of the present disclosure is shown schematically. Figure 6 An initial output curve of an unadjusted temperature sensor according to an embodiment of the present disclosure is illustrated schematically. Figure 7 The diagram illustrates the output curve after calibrating the nonlinear parameters according to an embodiment of the present disclosure. Figure 8 The diagram schematically illustrates the output curve after calibrating the temperature coefficient according to an embodiment of the present disclosure. Figure 9 The diagram illustrates the output curve after calibrating the zero-degree output parameters according to an embodiment of the present disclosure.

[0149] like Figure 5 As shown, the horizontal axis represents the actual measured temperature, and the vertical axis represents the output voltage of the temperature sensor. The output curve of a temperature sensor that has not undergone temperature calibration is significantly different from the expected output curve due to factors such as manufacturing processes. Figure 6 As shown, after adjusting the third adjustable resistor R4, the nonlinearity of the temperature sensor output curve was calibrated, and the linearity of the output curve was significantly improved. Figure 7 As shown, after adjusting the second adjustable resistor R3, the temperature sensor output curve is vertically biased and corrected. Figure 8 As shown, after adjusting the first adjustable resistor R2, the temperature sensor output curve was calibrated to zero degree. After three adjustments, the nonlinearity, temperature coefficient, and zero degree output of the output curve were all calibrated, and the output curve now closely matches the desired output curve.

[0150] According to embodiments of this disclosure, the temperature sensor includes a temperature sensing circuit and a signal conditioning circuit. The temperature sensing circuit is based on resistive temperature sensing, resulting in a small error source. By adjusting the adjustable parameters of the temperature sensing circuit and the signal conditioning circuit included in the temperature sensor, the nonlinear parameters, temperature coefficient, and zero-degree output parameters after adjustment are obtained. The adjustment process eliminates the influence of temperature on the temperature sensing of the temperature sensor. The circuit structure is simple, making adjustment easy and unaffected by power fluctuations. Furthermore, adjustment and calibration can be performed at any ambient temperature.

[0151] According to embodiments of this disclosure, during the actual calibration process, the temperature sensor calibration is completed when the adjustments of the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 all meet the expected results. If the adjustments of the first adjustable resistor R2, the second adjustable resistor R3, and the third adjustable resistor R4 do not meet the expected results, it can be determined that the temperature sensor is not functioning properly. This fully automated calibration algorithm ensures calibration accuracy while saving calibration time.

[0152] The flowcharts and block diagrams in the accompanying drawings schematically illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0153] Those skilled in the art will understand that the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments and / or claims of this disclosure can be combined or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0154] The embodiments of this disclosure have been described above. However, these embodiments are merely for illustrating the purpose, technical solutions, and beneficial effects of this disclosure, and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Without departing from the scope of this disclosure, various substitutions and modifications can be made by those skilled in the art within the spirit and principles of this disclosure, and all such substitutions and modifications should fall within the protection scope of this disclosure.

Claims

1. A temperature sensor, comprising: A temperature sensing circuit is used to determine a nonlinear parameter based on a third adjustable parameter and to determine a temperature coefficient based on a first adjustable parameter. The temperature sensing circuit includes a first resistor, a first adjustable resistor, and a second resistor. The positive feedback loop formed by the first resistor, the first adjustable resistor, and the second resistor forms a constant current source. as well as The signal conditioning circuit is used to determine the zero-degree output parameter based on the second adjustable parameter; The temperature sensor is used to determine the adjusted output curve based on the nonlinear parameter, the temperature coefficient, and the zero-degree output parameter. Wherein, the second adjustable parameter and the third adjustable parameter are parameters of the signal conditioning circuit, the first adjustable parameter is a parameter of the temperature sensing circuit, and the adjusted output curve is an output curve that is linearly related to temperature.

2. The temperature sensor of claim 1, wherein, The temperature sensing circuit also includes: a temperature sensing resistor and a third resistor; The first end of the first resistor is connected to the power supply voltage, and the second end is connected to the first end of the first adjustable resistor and the first end of the third resistor; The second end of the first adjustable resistor is connected to the first end of the temperature sensing resistor and the first end of the second resistor; The second terminal of the temperature sensing resistor is grounded; The second terminal of the second resistor is connected to the signal conditioning circuit; and The second end of the third resistor is connected to the signal conditioning circuit; Wherein, the first adjustable parameter is the parameter of the first adjustable resistor.

3. The temperature sensor of claim 2, wherein, The signal conditioning circuit includes: a second adjustable resistor, a third adjustable resistor, a fourth resistor, an operational amplifier, and an analog-to-digital converter; The first end of the second adjustable resistor is connected to the power supply voltage, and the second end is connected to the first end of the third adjustable resistor, the first end of the fourth resistor, and the negative input terminal of the operational amplifier. The second terminal of the third adjustable resistor is grounded; The second end of the fourth resistor is connected to the output of the operational amplifier, the input of the analog-to-digital converter, and the second end of the third resistor; The positive input terminal of the operational amplifier is connected to the second terminal of the second resistor; and The power supply terminal and reference voltage input terminal of the analog-to-digital converter are connected to the power supply voltage, and the ground terminal is grounded; Wherein, the second adjustable parameter is the parameter of the second adjustable resistor, and the third adjustable parameter is the parameter of the third adjustable resistor.

4. The temperature sensor of claim 3, wherein, The intersection of the second end of the fourth resistor, the output end of the operational amplifier, the input end of the analog-to-digital converter, and the second end of the third resistor is the output voltage acquisition point of the temperature sensor. The analog-to-digital converter is used to determine the output voltage based on the output voltage acquisition points; as well as The adjusted output curve is determined based on the reference voltage and the output voltage.

5. The temperature sensor according to claim 2, wherein the temperature sensing resistor is composed of a circuit having temperature information, and the circuit includes elements having temperature information.

6. The temperature sensor according to claim 3, wherein the first adjustable resistor, the second adjustable resistor and the third adjustable resistor are thin-film resistors and / or an adjustable resistor array composed of resistors and metal fuses.

7. The temperature sensor according to claim 4 further includes an external power supply; The external power source provides the power supply voltage and the reference voltage to the temperature sensor.

8. A temperature adjustment and calibration method for a temperature sensor according to any one of claims 1-7, comprising: The nonlinear parameters are determined based on the second and third adjustable parameters; When the nonlinear parameter meets the preset conditions, the temperature coefficient is determined according to the first adjustable parameter; When the temperature coefficient meets the preset conditions, the zero-degree output parameter is determined according to the second adjustable parameter; as well as The temperature sensor is calibrated once the zero-degree output parameters meet the preset conditions. Wherein, the second adjustable parameter, the third adjustable parameter, and the zero-degree output parameter are parameters of the signal conditioning circuit, and the nonlinear parameter, the temperature coefficient, and the first adjustable parameter are parameters of the temperature sensing circuit.

9. The method of claim 8, wherein, The temperature sensing circuit includes: a first adjustable resistor; The signal conditioning circuit includes: a second adjustable resistor and a third adjustable resistor; The first adjustable parameter is adjusted by adjusting the resistance value of the first adjustable resistor; The second adjustable parameter is adjusted by adjusting the resistance value of the second adjustable resistor; and The third adjustable parameter is adjusted by adjusting the resistance value of the third adjustable resistor.

10. The method of claim 9, wherein, The adjustment of the first adjustable resistor value, the second adjustable resistor value, and the third adjustable resistor value includes any one of the following methods or a combination of the following methods: discrete adjustment, continuous adjustment, and fuse adjustment.

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