Temperature compensation method for three-terminal adjustable shunt reference voltage source

Abstract

The invention provides a temperature compensation method of a three-terminal adjustable shunt reference voltage source. The method comprises the following steps: obtaining a zero temperature coefficient point measured value of a reference voltage of the three-terminal adjustable shunt reference voltage source in a set temperature interval; according to the drift direction of the measured value of the zero temperature coefficient point, the base emitter voltage variation of two input tubes of a differential amplifier in the three-end adjustable shunt reference voltage source is adjusted, so that the drift distance of the measured value of the zero temperature coefficient point is reduced, and temperature compensation is achieved. By means of the temperature compensation method of the three-end adjustable shunt reference voltage source, the problem that in the prior art, the reference voltage of a voltage reference chip exceeds the error range along with temperature change is solved.

Description

Technical Field

[0001] The invention relates to the technical field of electronic circuits, and in particular to a temperature compensation method for a three-terminal adjustable shunt reference voltage source. Background Art

[0002] Voltage reference chips, such as the three-terminal adjustable shunt reference voltage source, as the name suggests, provide an accurate output voltage that is basically unaffected by operating voltage, load, temperature changes and time. Therefore, voltage reference chips can be used in high-precision A / D and D / A conversion, sensors, power management, precision rectification and other fields that require higher precision voltage standards.

[0003] Affected by factors such as weather, working environment, and system heating, high temperature can cause the output voltage of the voltage reference chip to change; and the field of high-precision voltage standards requires a stable output voltage, which requires that the voltage reference chip is little affected by temperature. The chip needs a constant voltage reference that is independent of the power supply voltage and has a low temperature drift. Generally, a zero temperature coefficient reference voltage is generated by adding a negative temperature coefficient voltage and a positive temperature coefficient voltage with appropriate weights.

[0004] In order to generate a reference voltage with a zero temperature coefficient, the reference voltage chip has a temperature compensation function. In theory, the reference voltage changes very little with temperature. However, due to different production processes and the influence of various parasitic parameters, as the temperature rises or falls, the zero temperature coefficient point of the reference voltage chip is not at the optimal temperature point, which leads to a large change in the reference voltage and there is a risk of exceeding the error range. Summary of the invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a temperature compensation method for a three-terminal adjustable shunt reference voltage source, which is used to solve the problem that the reference voltage of the voltage reference chip in the prior art varies with temperature and exceeds the error range.

[0006] To achieve the above-mentioned object and other related objects, the present invention provides a temperature compensation method for a three-terminal adjustable shunt reference voltage source, the temperature compensation method comprising:

[0007] Step S1: obtaining a measured value of a zero temperature coefficient point of a reference voltage of the three-terminal adjustable shunt reference voltage source within a set temperature range;

[0008] Step S2: According to the drift direction of the measured value of the zero temperature coefficient point, the base-emitter voltage variation of the two input tubes of the differential amplifier in the three-terminal adjustable shunt reference voltage source is adjusted to reduce the drift of the measured value of the zero temperature coefficient point and realize temperature compensation.

[0009] Optionally, the temperature compensation method further includes step S3: repeatedly executing step S1 and step S2 until the measured value of the zero temperature coefficient point meets the requirement.

[0010] Optionally, the method for judging whether the measured value of the zero temperature coefficient point meets the requirement includes:

[0011] Obtain the difference between the temperature midpoint of the set temperature range and the actual measured value of the zero temperature coefficient point, compare the absolute value of the difference with the absolute value of the allowable error, if the absolute value of the difference is not greater than the absolute value of the allowable error, judge that the actual measured value of the zero temperature coefficient point meets the requirements, otherwise, judge that the actual measured value of the zero temperature coefficient point does not meet the requirements.

[0012] Optionally, the method for obtaining the measured value of the zero temperature coefficient point includes:

[0013] Several temperature points are selected within the set temperature range, and the reference voltage of the three-terminal adjustable shunt reference voltage source at different temperature points is tested to obtain a relationship curve between the reference voltage and temperature of the three-terminal adjustable shunt reference voltage source, and thereby obtain the actual measured value of the zero temperature coefficient point.

[0014] Optionally, the method for obtaining the relationship curve between the reference voltage and temperature includes:

[0015] Building a test circuit by using the three-terminal adjustable shunt reference voltage source, and placing the test circuit in a temperature control device;

[0016] The test circuit is tested at different temperature points to obtain corresponding reference voltages, and each temperature point and its corresponding reference voltage are fitted to obtain a relationship curve between the reference voltage and temperature.

[0017] Optionally, the test circuit includes a three-terminal adjustable shunt reference voltage source, the cathode of which is connected to the input current and short-circuited with the reference pole, and the anode is grounded; or, the test circuit includes a three-terminal adjustable shunt reference voltage source and a current limiting resistor, the cathode of the three-terminal adjustable shunt reference voltage source is connected to the input voltage via the current limiting resistor and short-circuited with the reference pole, and the anode is grounded.

[0018] Optionally, the method for obtaining the drift direction of the zero temperature coefficient point measured value includes:

[0019] Obtaining a first boundary point and a second boundary point according to a temperature midpoint and an allowable error of the set temperature interval, wherein the first boundary point is smaller than the second boundary point;

[0020] Compare the measured value of the zero temperature coefficient point with the first boundary point and the second boundary point respectively;

[0021] If the measured value of the zero temperature coefficient point is less than the first boundary point, the measured value of the zero temperature coefficient point drifts and the drift direction is a first direction;

[0022] If the measured value of the zero temperature coefficient point is greater than the second boundary point, the measured value of the zero temperature coefficient point drifts and the drift direction is the second direction.

[0023] Optionally, the base-emitter voltage variation of the two input tubes in the differential amplifier is adjusted by adjusting the area ratio of the second input tube to the first input tube of the differential amplifier and / or the resistance value of the base series resistor of the second input tube.

[0024] Optionally, the area ratio of the second input pipe to the first input pipe is adjusted by reducing the area of ​​the second input pipe or the first input pipe.

[0025] Optionally, when step S2 is repeatedly executed, the resistance of the base series resistor is first adjusted; if the corresponding measured value of the zero temperature coefficient point still does not meet the requirement when the resistance of the base series resistor reaches an extreme value, the area ratio of the second input tube to the first input tube is adjusted until the measured value of the zero temperature coefficient point meets the requirement.

[0026] As described above, the temperature compensation method of the three-terminal adjustable shunt reference voltage source of the present invention reduces the drift of the measured value of the zero temperature coefficient point by adjusting the base-emitter voltage change of the two input tubes of the differential amplifier in the three-terminal adjustable shunt reference voltage source according to the drift direction of the measured value of the zero temperature coefficient point, thereby realizing temperature compensation of the reference voltage, reducing the high temperature error of the reference voltage (the error is reduced from about 25mV to less than 10mV), and improving the accuracy of the reference voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Shown is a structural schematic diagram of a three-terminal adjustable shunt reference voltage source.

[0028] Figure 2 A temperature characteristic curve diagram of a three-terminal adjustable shunt reference voltage source is shown.

[0029] Figure 3 Another temperature characteristic diagram of a three-terminal adjustable shunt reference voltage source is shown.

[0030] Figure 4 Shown is a flow chart of the temperature compensation method of the present invention.

[0031] Figure 5 Shown is a structural schematic diagram of the test circuit of the present invention.

[0032] Figure 6 Another structural schematic diagram of the test circuit of the present invention is shown.

[0033] Figure 7 Shown is a schematic diagram of the temperature characteristic curve of a three-terminal adjustable shunt reference voltage source after temperature compensation. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0035] See also Figures 1 to 7 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the form, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0036] The structure of the three-terminal adjustable shunt reference voltage source is as follows Figure 1 As shown, transistor Q2 and transistor Q3 form an input stage, transistor Q4 and transistor Q5 form a bandgap reference, transistor Q8 and transistor Q9 form a mirror constant current source and form a differential amplifier with transistor Q7, transistor Q6 and transistor Q1 as an intermediate stage, and transistor Q10 and transistor Q11 form a Darlington transistor as an output stage, wherein the resistor, capacitor and diode play the role of bias, compensation and protection respectively.

[0037] for Figure 1 The key to obtaining a stable reference voltage VREF in the three-terminal adjustable shunt reference voltage source shown is the balance between transistor Q9 and transistor Q1: when the output voltage reaches the target value, the reference voltage VREF = 2.5V, and the current flowing through transistor Q9 is approximately equal to the current flowing through transistor Q1. If the above balance changes due to changes in the target value, the current flowing through transistor Q9 or transistor Q1 will change, reducing or increasing the reference voltage VREF, causing the zero temperature coefficient point of the reference voltage VREF to drift.

[0038] All transistors used in a three-terminal adjustable shunt reference are assumed to have a high current gain, β, which means that the base current of the transistor is negligible.

[0039] In a balanced state, assuming that the current flowing through transistor Q9 is equal to the current flowing through transistor Q1 and is equal to I1, transistor Q8 and transistor Q9 form a current mirror structure and the current mirror ratio is 1:1, so the current flowing through transistor Q8 is equal to I1, and the current flowing through transistor Q7 and transistor Q6 is also equal to I1; in addition, transistor Q1 and transistor Q4 form a current mirror structure and the current mirror ratio is 1:3, so the current flowing through transistor Q4 is equal to 3*I1.

[0040] Assume that the resistance ratio of resistor R2 to resistor R3 is 1:3, and resistor R2 and resistor R3 have the same voltage drop; and assume that the area ratio of transistor Q4 to transistor Q5 is 1:2, at room temperature of 27°C, V T =26mV, and then according to the values ​​of resistors R1, R2 and R4, the reference voltage VREF=VR1+VR2+VBE_Q2+VBE_Q4=2.495V is calculated, wherein VR1 is the voltage drop across resistor R1, VR2 is the voltage drop across resistor R2, VBE_Q2 is the base-emitter voltage of transistor Q2, and VBE_Q4 is the base-emitter voltage of transistor Q4.

[0041] It can be seen that in the three-terminal adjustable shunt reference voltage source, in order to obtain a reference voltage VREF of 2.495V, after the area ratio of transistor Q4 and transistor Q5, the resistance ratio of resistor R2 and resistor R3, and the resistance value of resistor R4 are determined, the current mirror ratio of transistor Q4 and transistor Q1 is also determined, and the tiny differential output current (i.e., the base current of transistor Q10) generated by the 1:1 differential amplifier formed by transistor Q1 and transistor Q6 keeps the whole system balanced.

[0042] However, in the actual chip production process, the current gain β of the transistor is not very high, generally between 100 and 200. The base current cannot be completely ignored. In addition, with the existence of various parasitic parameters, the zero temperature coefficient point of the reference voltage VREF is not at the optimal temperature point, but will drift. The actual measured temperature characteristic curve of the reference voltage VREF is as follows: Figure 2 and Figure 3 shown.

[0043] In the entire temperature range of -40℃~125℃, Figure 2 It shows that the reference voltage VREF decreases gradually as the temperature rises, and the zero temperature coefficient point drifts to around -40°C. Figure 3It shows that the reference voltage VREF first increases gradually and then decreases as the temperature rises, and the zero temperature coefficient point drifts to about 80°C; wherein, the maximum change of the reference voltage VREF reaches about 25mV, and the error range is close to 1%, while the conventional reference voltage VREF is generally divided into two levels of ±0.5% and ±1% according to the error. Therefore, the reference voltage VREF of the three-terminal adjustable shunt reference voltage source in the prior art has the risk of exceeding the error range.

[0044] In order to solve the above technical problems, Figure 4 As shown, this embodiment provides a temperature compensation method for a three-terminal adjustable shunt reference voltage source, including step S1 and step S2; further, it also includes step S3.

[0045] Step S1: obtaining a measured value of a zero temperature coefficient point of a reference voltage of a three-terminal adjustable shunt reference voltage source within a set temperature range.

[0046] Specifically, the method for obtaining the measured value of the zero temperature coefficient point includes: selecting several temperature points within a set temperature range, testing the reference voltage of a three-terminal adjustable shunt reference voltage source at different temperature points, obtaining a curve showing the relationship between the reference voltage and temperature of the three-terminal adjustable shunt reference voltage source, and thereby obtaining the measured value of the zero temperature coefficient point of the reference voltage of the three-terminal adjustable shunt reference voltage source.

[0047] The set temperature interval is a temperature range defined by a minimum temperature point and a maximum temperature point, such as -40°C to 125°C, -55°C to 125°C, etc., which is determined by actual application requirements.

[0048] When selecting temperature points, the minimum temperature point can be used as the starting point and the maximum temperature point as the end point, and the method is implemented by superimposing fixed increments, wherein the number of fixed increments can be one or more than one. When the number of fixed increments is greater than one, the number of times each fixed increment is used is not limited and each fixed increment can be used continuously or alternately. Of course, other temperature point selection methods are also applicable, such as random selection methods, which have no substantial impact on this embodiment.

[0049] Taking the set temperature range of -40℃~125℃ as an example, the temperature points are selected according to the three fixed increments of 10℃, 15℃ and 25℃. Among them, the fixed increment of 10℃ is used 5 times in a row, the fixed increment of 15℃ is used 6 times in a row, and the fixed increment of 25℃ is used once. The final selected temperature points include: -40℃, -30℃, -20℃, -10℃, 0℃, 10℃, 25℃, 40℃, 55℃, 70℃, 85℃, 100℃, 125℃. Figure 2 and Figure 3 shown.

[0050] It should be noted that in order to accurately characterize the relationship curve between the reference voltage and temperature of the three-terminal adjustable shunt reference voltage source within the set temperature range, the selected temperature points should try to cover the entire set temperature range and the number should be moderate. Too few points cannot accurately characterize the relationship curve, and too many points will result in too long a test time.

[0051] Among them, the method for obtaining the relationship curve between the reference voltage and the temperature includes: building a test circuit through a three-terminal adjustable shunt reference voltage source, and placing the test circuit in a temperature control device; testing the test circuit at different temperature points to obtain the corresponding reference voltage, fitting each temperature point and its corresponding reference voltage, and obtaining the relationship curve between the reference voltage and the temperature of the three-terminal adjustable shunt reference voltage source.

[0052] In one possible implementation, a test circuit constructed by a three-terminal adjustable shunt reference voltage source is as follows: Figure 5 As shown in FIG. 1 , the test circuit includes a three-terminal adjustable shunt reference voltage source, the cathode K is connected to the input current Iin and short-circuited with the reference electrode R, and the anode A is grounded. Figure 5 The test circuit shown is placed in a temperature control device, an input power supply provides an input current Iin to the test circuit outside the temperature control device, and a measuring instrument measures a reference voltage VREF between a reference electrode R and an anode A outside the temperature control device.

[0053] In another possible implementation, a test circuit constructed by a three-terminal adjustable shunt reference voltage source is as follows: Figure 6 As shown in FIG. 1 , the test circuit includes a three-terminal adjustable shunt reference voltage source and a current limiting resistor Ri. The cathode K of the three-terminal adjustable shunt reference voltage source is connected to the input voltage VIN through the current limiting resistor Ri and is short-circuited with the reference electrode R. The anode A is grounded. Figure 6 The test circuit shown is placed in a temperature control device, an input power supply provides an input voltage Vin to the test circuit outside the temperature control device, and a measuring instrument measures a reference voltage VREF between a reference electrode R and an anode A outside the temperature control device.

[0054] In the above two implementations, since the current limiting resistor Ri will be affected by temperature, thereby affecting the measurement accuracy of the reference voltage VREF, the first implementation is usually selected to measure the reference voltage VREF. Of course, other test circuit structures that can accurately measure the reference voltage VREF built by a three-terminal adjustable shunt reference voltage source are also applicable, and this embodiment does not limit this.

[0055] Among them, the method for obtaining the actual measured value of the zero temperature coefficient point according to the relationship curve between the reference voltage and temperature includes: in the relationship curve between the reference voltage and temperature of the three-terminal adjustable shunt reference voltage source, taking the temperature point corresponding to the maximum value of the reference voltage as the actual measured value of the zero temperature coefficient point.

[0056] Step S2: According to the drift direction of the measured value of the zero temperature coefficient point, the base-emitter voltage variation of the two input tubes of the differential amplifier in the three-terminal adjustable shunt reference voltage source is adjusted to reduce the drift of the measured value of the zero temperature coefficient point and realize temperature compensation.

[0057] Specifically, the method for obtaining the drift direction of the zero temperature coefficient point measured value includes: obtaining the first boundary point and the second boundary point according to the temperature midpoint and the allowable error of the set temperature range, the first boundary point is smaller than the second boundary point; comparing the zero temperature coefficient point measured value with the first boundary point and the second boundary point respectively, if the zero temperature coefficient point measured value is smaller than the first boundary point, then the zero temperature coefficient point measured value drifts and the drift direction is the first direction, if the zero temperature coefficient point measured value is larger than the second boundary point, then the zero temperature coefficient point measured value drifts and the drift direction is the second direction, if the zero temperature coefficient point measured value is between the first boundary point and the second boundary point, then the zero temperature coefficient point measured value does not drift. Among them, the size of the allowable error is determined by the actual application requirements, and this embodiment does not limit this.

[0058] The method for adjusting the base-emitter voltage variation of two input tubes of a differential amplifier includes: adjusting the base-emitter voltage variation of the two input tubes in the differential amplifier by adjusting the area ratio of the second input tube (i.e., transistor Q1) to the first input tube (i.e., transistor Q6) of the differential amplifier and / or the resistance value of the base series resistor (i.e., resistor R5) of the second input tube.

[0059] In this embodiment, the base-emitter voltage variation of the two input tubes in the differential amplifier can be adjusted only by adjusting the area ratio of the second input tube to the first input tube, or only by adjusting the resistance value of the base series resistor, or by adjusting the area ratio of the second input tube to the first input tube and the resistance value of the base series resistor at the same time.

[0060] When adjusting the area ratio of the second input tube to the first input tube, the area ratio can be adjusted by adjusting only the area of ​​the second input tube, or by adjusting only the area of ​​the first input tube, or by adjusting both the areas of the second input tube and the first input tube. In applications, in order to avoid excessive chip layout modifications, the area ratio is generally adjusted by reducing the area of ​​the second input tube or the first input tube.

[0061] In the three-terminal adjustable shunt reference voltage source of this embodiment, the two input tubes of the differential amplifier are bipolar transistors, and the base-emitter voltage of the bipolar transistor has a negative temperature coefficient, satisfying the formula V T =kT / q,I C =I Sexp(VBE / V T ), m≈ -3 / 2, Eg≈1.12eV, and through theoretical derivation, formula 1 is obtained: where VBE is the base-emitter voltage of the bipolar transistor, V T is the threshold voltage of the bipolar transistor, I C is the collector current of the bipolar transistor, I S is the saturation current of the bipolar transistor, k is the Boltzmann constant, T is the thermodynamic temperature, q is the electron charge, and b is the proportionality coefficient.

[0062] According to formula 1, under the condition that T is fixed, the larger VBE is, the smaller the absolute value of the negative temperature coefficient voltage is. Among them, the absolute value of the negative temperature coefficient voltage represents the change amount of VBE at a fixed temperature; and the smaller the absolute value of the negative temperature coefficient voltage is, the smaller the change amount of VBE is. When the measured value of the zero temperature coefficient point drifts in the first direction (such as Figure 2 the zero temperature coefficient point in is about -40 °C), by reducing the area ratio of the second input transistor to the first input transistor and / or the value of the base series resistance, the base-emitter voltage of the second input transistor is made greater than the base-emitter voltage of the first input transistor, that is, VBE_Q1 > VBE_Q6. In this way, the change amount of the base-emitter voltage of the second input transistor under the same temperature change is made smaller than the change amount of the base-emitter voltage of the first input transistor, that is, ΔVBE_Q1 < ΔVBE_Q6, improving the input offset of the differential amplifier, so that the current flowing through transistor Q9 is less than the current flowing through transistor Q1, thereby increasing the reference voltage VREF.

[0063] When the measured value of the zero temperature coefficient point drifts in the second direction (such as Figure 3 the zero temperature coefficient point in is about 80 °C), by increasing the area ratio of the second input transistor to the first input transistor and / or the value of the base series resistance, the base-emitter voltage of the second input transistor is made less than the base-emitter voltage of the first input transistor, that is, VBE_Q1 < VBE_Q6. In this way, the change amount of the base-emitter voltage of the second input transistor under the same temperature change is made greater than the change amount of the base-emitter voltage of the first input transistor, that is, ΔVBE_Q1 > ΔVBE_Q6, improving the input offset of the differential amplifier, so that the current flowing through transistor Q9 is greater than the current flowing through transistor Q1, thereby reducing the reference voltage VREF.

[0064] Step S3: Repeat steps S1 and S2 until the measured value of the zero temperature coefficient point of the reference voltage of the three-terminal adjustable shunt reference voltage source meets the requirements.

[0065] Specifically, the method for judging whether the actual measured value of the zero temperature coefficient point meets the requirements includes: obtaining the difference between the temperature midpoint of the set temperature range and the actual measured value of the zero temperature coefficient point, comparing the absolute value of the difference with the absolute value of the allowable error, if the absolute value of the difference is not greater than the absolute value of the allowable error, judging that the actual measured value of the zero temperature coefficient point meets the requirements, otherwise, judging that the actual measured value of the zero temperature coefficient point does not meet the requirements.

[0066] When step S2 is repeatedly executed, the resistance value of the base series resistor is adjusted first. If the actual measured value of the corresponding zero temperature coefficient point still does not meet the requirement when the resistance value of the base series resistor reaches the extreme value, the area ratio of the second input tube to the first input tube is adjusted until the actual measured value of the zero temperature coefficient point meets the requirement. Through the above adjustment method, the number of chip layout modifications can be minimized.

[0067] Among them, the extreme value includes a minimum value and a maximum value, the minimum value is zero, and the maximum value is determined by the layout area of ​​the resistor. In the case where the measured value of the zero temperature coefficient point drifts in the first direction, the resistance of the base series resistor is first reduced. If the corresponding measured value of the zero temperature coefficient point still does not meet the requirements when the resistance of the base series resistor is reduced to the minimum value (i.e., zero), the area ratio of the second input tube to the first input tube is reduced until the corresponding measured value of the zero temperature coefficient point meets the requirements; when the measured value of the zero temperature coefficient point drifts in the second direction, the resistance of the base series resistor is first increased. If the corresponding measured value of the zero temperature coefficient point still does not meet the requirements when the resistance of the base series resistor is increased to the maximum value, the area ratio of the second input tube to the first input tube is increased until the corresponding measured value of the zero temperature coefficient point meets the requirements.

[0068] For a three-terminal adjustable shunt reference voltage source, when designing the chip, the area ratio of the second input tube to the first input tube is 1:1, and the resistance value of the base series resistor is between 3KΩ and 5KΩ. However, due to the process parameter differences caused by the device production process and the influence of various parasitic parameters, etc., the input offset of the differential amplifier will be caused, causing the zero temperature coefficient point of the reference voltage to drift. This embodiment adjusts the area ratio of the second input tube to the first input tube and / or the resistance value of the base series resistor in the differential amplifier according to the shape of the actually measured temperature characteristic curve to improve the input offset of the differential amplifier and realize temperature compensation of the reference voltage. The temperature characteristic curve actually measured after temperature compensation is as follows: Figure 7 As shown, the zero temperature coefficient point of the reference voltage is near 40°C, the temperature characteristic curve is basically symmetrical, and within the entire set temperature range, the maximum change of the reference voltage VREF is within 10mV, which greatly reduces the influence of temperature on the reference voltage VREF.

[0069] In fact, the above temperature compensation method can be applied to the chip generation process. For example, after the first tape-out according to the initial design, several chips are selected for the above test to obtain multiple sets of adjustment parameters, and the final adjustment parameters are obtained based on the multiple sets of adjustment parameters to modify the initial design, thereby reducing the number of revisions in the chip design process and reducing the tape-out cost in the chip production process.

[0070] In summary, the temperature compensation method of a three-terminal adjustable shunt reference voltage source of the present invention reduces the drift of the zero temperature coefficient point measured value by adjusting the base-emitter voltage variation of the two input tubes of the differential amplifier in the three-terminal adjustable shunt reference voltage source according to the drift direction of the zero temperature coefficient point measured value, thereby achieving temperature compensation for the reference voltage, reducing the high temperature error of the reference voltage (the error is reduced from about 25mV to less than 10mV), and improving the accuracy of the reference voltage. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0071] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A temperature compensation method for a three-terminal adjustable shunt reference voltage source, characterized in that: The temperature compensation method comprises: Step S1: obtaining a measured value of a zero temperature coefficient point of a reference voltage of the three-terminal adjustable shunt reference voltage source within a set temperature range; Step S2: According to the drift direction of the measured value of the zero temperature coefficient point, the base-emitter voltage variation of the two input tubes of the differential amplifier in the three-terminal adjustable shunt reference voltage source is adjusted to reduce the drift of the measured value of the zero temperature coefficient point and realize temperature compensation.

2. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 1, characterized in that: The temperature compensation method further comprises step S3: repeatedly executing step S1 and step S2 until the measured value of the zero temperature coefficient point meets the requirement.

3. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 2, characterized in that: The method for judging whether the measured value of the zero temperature coefficient point meets the requirement includes: Obtain the difference between the temperature midpoint of the set temperature range and the actual measured value of the zero temperature coefficient point, compare the absolute value of the difference with the absolute value of the allowable error, if the absolute value of the difference is not greater than the absolute value of the allowable error, judge that the actual measured value of the zero temperature coefficient point meets the requirements, otherwise, judge that the actual measured value of the zero temperature coefficient point does not meet the requirements.

4. The temperature compensation method of a three-terminal adjustable shunt reference voltage source according to any one of claims 1 to 3, characterized in that: The method for obtaining the measured value of the zero temperature coefficient point includes: Several temperature points are selected within the set temperature range, and the reference voltage of the three-terminal adjustable shunt reference voltage source at different temperature points is tested to obtain a relationship curve between the reference voltage and temperature of the three-terminal adjustable shunt reference voltage source, and thereby obtain the actual measured value of the zero temperature coefficient point.

5. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 4, characterized in that: The method for obtaining the relationship curve between the reference voltage and temperature includes: Building a test circuit by using the three-terminal adjustable shunt reference voltage source, and placing the test circuit in a temperature control device; The test circuit is tested at different temperature points to obtain corresponding reference voltages, and each temperature point and its corresponding reference voltage are fitted to obtain a relationship curve between the reference voltage and temperature.

6. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 5, characterized in that: The test circuit includes a three-terminal adjustable shunt reference voltage source, the cathode of which is connected to the input current and short-circuited with the reference electrode, and the anode is grounded; or, the test circuit includes a three-terminal adjustable shunt reference voltage source and a current limiting resistor, the cathode of the three-terminal adjustable shunt reference voltage source is connected to the input voltage via the current limiting resistor and short-circuited with the reference electrode, and the anode is grounded.

7. The temperature compensation method of a three-terminal adjustable shunt reference voltage source according to any one of claims 1 to 3, characterized in that: The method for obtaining the drift direction of the zero temperature coefficient point measured value includes: Obtaining a first boundary point and a second boundary point according to a temperature midpoint and an allowable error of the set temperature interval, wherein the first boundary point is smaller than the second boundary point; Compare the measured value of the zero temperature coefficient point with the first boundary point and the second boundary point respectively; If the measured value of the zero temperature coefficient point is less than the first boundary point, the measured value of the zero temperature coefficient point drifts and the drift direction is a first direction; If the measured value of the zero temperature coefficient point is greater than the second boundary point, the measured value of the zero temperature coefficient point drifts and the drift direction is the second direction.

8. The temperature compensation method of a three-terminal adjustable shunt reference voltage source according to any one of claims 1 to 3, characterized in that: The base-emitter voltage variation of the two input tubes in the differential amplifier is adjusted by adjusting the area ratio of the second input tube to the first input tube and / or the resistance value of the base series resistor of the second input tube.

9. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 8, characterized in that: The area ratio of the second inlet pipe to the first inlet pipe is adjusted by reducing the area of ​​the second inlet pipe or the first inlet pipe.

10. The temperature compensation method of the three-terminal adjustable shunt reference voltage source according to claim 8, characterized in that: When step S2 is repeatedly executed, the resistance value of the base series resistor is first adjusted. If the corresponding measured value of the zero temperature coefficient point still does not meet the requirement when the resistance value of the base series resistor reaches an extreme value, the area ratio of the second input tube to the first input tube is adjusted until the measured value of the zero temperature coefficient point meets the requirement.

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