A constant temperature point temperature compensation device, method and equipment of a precision temperature control circuit

Abstract

The present specification discloses a constant temperature point compensation method of a precision temperature control circuit, comprising a feedback network, an operational amplifier and a temperature control bridge: the temperature control bridge comprises a temperature control branch and a compensation branch, the temperature control branch is a proportional integral temperature control circuit, the compensation branch replaces a fixed resistor in the existing proportional integral temperature control circuit, and is arranged in a constant temperature area of the precision temperature control circuit, the compensation branch is a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network, which is composed of a thermistor and a plurality of fixed resistors through series-parallel connection, by configuring the compensation branch parameters and reasonably configuring the position of the compensation thermistor, it is ensured that ΔU=V ‑ ‑V + changes from large to small, so that the heating power W J changes from large to small with the rise of the external environment temperature, and the heat dissipation power W S maintains balance. The present application can greatly improve the temperature control precision without changing the constant temperature structure, so that the constant temperature crystal oscillator obtains excellent frequency temperature stability.

Description

Technical Field

[0001] This document relates to the field of precision temperature control technology for isothermal crystal oscillators, and in particular to a constant temperature point temperature compensation device, method and equipment for a precision temperature control circuit. Background Technology

[0002] Oven-controlled crystal oscillators (OCOs) are widely used in communication, radar, navigation, remote sensing, and measuring instruments due to their high frequency stability and excellent aging characteristics. As the frequency source or time reference of electronic systems, their performance directly affects or even determines the performance of the electronic system. Among OCOs, precision temperature control circuits are widely used because of their high temperature control capability and ability to achieve high temperature control accuracy. Precision temperature control circuits come in various forms, each with its own characteristics. Proportional-integral (PI) temperature control circuits have strong resistance to thermal oscillations, can achieve a high reduction factor, and have strong temperature control capabilities, and have been widely used in OCOs in recent years.

[0003] By employing a proportional-integral (PI) temperature control circuit and rationally designing the integral parameters, the temperature control accuracy of the isothermal crystal oscillator in the isothermal zone is significantly improved, and its frequency-temperature stability is markedly enhanced. However, when the ambient temperature changes, the isothermal point temperature still exhibits an inherent deviation, such as... Figure 1 The diagram shown illustrates the principle of a proportional-integral temperature control circuit in the prior art. Its mechanism is as follows: Under equilibrium conditions, the heat dissipation power W of the isothermal crystal oscillator... S Equal to the heating power (W) of the temperature control circuit J Let the voltage difference at the input terminals of the operational amplifier be ΔU, and the output voltage be U. 01 Then W J ∝U 01 U 01 ∝ΔU, W S ∝ΔU, at this time, ΔU is expressed as: ΔU=V - -V + =R T *E / (R1+R T )-R3*E / (R2+R3).

[0004] As can be seen from the above formula, when the ambient temperature changes from low to high, the heat dissipation power W in the equilibrium state... S If V changes from large to small, then ΔU also changes from large to small. - and V + The system consists of two components, where R1, R2, and R3 are fixed resistors with a temperature coefficient approximately zero. T This is a thermistor. Ideally, without considering the temperature characteristics of the power supply E, ΔU only interacts with R. T Regarding this, the change in ΔU means that R T Changes are about to occur, and R TA change means that the constant temperature point T K Things have changed.

[0005] However, although the proportional-integral temperature control circuit has a large equivalent loop amplification factor, when converted to R... T The changes above are relatively small, resulting in a shift in the isothermal point ΔT. K While the temperature difference is relatively small, in demanding applications, the migration of the isothermal point temperature with changes in ambient temperature remains significant and is a major factor affecting the frequency temperature stability of the isothermal crystal oscillator. Therefore, further improvements are still needed. Summary of the Invention

[0006] This specification provides a method for compensating the isothermal point of a precision temperature control circuit to solve the problem of temperature migration at the isothermal point, which leads to low frequency temperature stability of the isothermal crystal oscillator.

[0007] In a first aspect, the present invention provides a constant temperature point compensation device for a precision temperature control circuit, comprising a feedback network and an operational amplifier, wherein the temperature compensation device further comprises a temperature control bridge.

[0008] The first and second output terminals of the temperature control bridge are respectively connected to the first and second input terminals of the operational amplifier. The first output terminal of the temperature control bridge and the first input terminal of the operational amplifier are connected to the first connection terminal of the feedback network. The second connection terminal of the feedback network is connected to the output terminal of the operational amplifier.

[0009] The temperature control bridge includes a temperature control branch and a compensation branch:

[0010] The temperature control branch is a proportional-integral (PI) temperature control circuit, which includes fixed resistors R1, R3, R4, and R5, and a thermistor R. T and compensation branch lines;

[0011] The compensation branch is located in the constant temperature region of the precision temperature control circuit;

[0012] The input terminal of the fixed resistor R1 is connected to the input terminal of the compensation branch as the input terminal of the temperature control bridge; the output terminal of the fixed resistor R1 is connected to the thermistor R T After the input terminal of the compensation branch is connected, it is connected together with the input terminal of the fixed resistor R4; after the output terminal of the compensation branch is connected to the input terminal of the fixed resistor R3, it is connected together with the input terminal of the fixed resistor R5; the thermistor R T The output terminal of the fixed resistor R4 is grounded, and the output terminal of the fixed resistor R5 is grounded. The output terminal of the fixed resistor R4 serves as the first output terminal of the temperature control bridge.

[0013] In some preferred embodiments, the temperature of the compensation branch is lower than the preset temperature of the constant temperature point but higher than the ambient temperature.

[0014] In some preferred embodiments, the compensation branch is a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network.

[0015] In some preferred embodiments, the negative temperature coefficient thermistor or negative temperature coefficient thermistor network has the following mapping relationship with ambient temperature:

[0016] R TB =R TB0 [exp(B(1 / (273+T R )-1 / (273+T0)))]

[0017] Where T0 is the ambient temperature, R TB0 B is the resistance of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network at room temperature, and T is the thermistor constant of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network. R To compensate for the temperature at the location of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network, R TB It refers to the resistance of a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network as the ambient temperature changes.

[0018] In some preferred embodiments, the operational amplifier has a voltage difference between its positive and negative terminals as follows:

[0019] ΔU=V - -V +

[0020] Where ΔU is the voltage difference between the positive and negative terminals of the operational amplifier, V - V is the voltage at the negative terminal of the operational amplifier. + This is the voltage at the positive terminal of the operational amplifier.

[0021] In some preferred embodiments, the voltage at the positive terminal of the operational amplifier is mapped to the negative temperature coefficient thermistor or negative temperature coefficient thermistor network as follows:

[0022] V + =R3*E / (R TB +R3)

[0023] Where R3 is the resistance value of the third resistor in the temperature compensation branch, and E is the input level of the temperature compensation branch.

[0024] In another aspect, the present invention provides a method for compensating the constant temperature point of a precision temperature control circuit. Based on the aforementioned device for compensating the constant temperature point of a precision temperature control circuit, the temperature compensation method includes:

[0025] Step S10: At room temperature, set the resistance of the precision resistance box of the temperature compensation device to R0, and after the frequency of the precision temperature control circuit stabilizes, obtain the output frequency F0 of the constant temperature crystal oscillator.

[0026] Step S20: Reduce the temperature of the precision resistance box to the lowest value T within its operating temperature range. L After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. L ;

[0027] The temperature of the precision resistance box is raised to the highest value T in its operating temperature range. H After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. H ;

[0028] Step S30, obtain the ambient temperature as T L T0, T H At that time, the compensation branch resistance R TB The corresponding actual temperature T RL T R0 T RH ;

[0029] Step S40, based on the external temperature T L T0, T H and compensation branch resistance R TB The actual temperature T RL T R0 T RH The corresponding precision resistor box resistance value R L R0, R H Obtain the compensation branch parameters R B1 R B2 R B3 ;

[0030] Step S50, based on the compensation branch parameters R B1 R B2 R B3 Configure compensation branches to achieve constant temperature compensation at the constant temperature point of the precision temperature control circuit.

[0031] In some preferred embodiments, step S50 is based on the compensation branch parameter RB1 R B2 R B3 After configuring the compensation branch, the compensation branch parameter R is also set. B1 R B2 R B3 The fine-tuning steps are as follows:

[0032] Step S60, to compensate branch parameters R B1 R B2 R B3 Configure the compensation branch and test the frequency-temperature characteristic curve of the cryogenic crystal oscillator;

[0033] Step S70: Calculate the compensation branch parameter R based on the frequency-temperature characteristic curve. B1 R B2 R B3 The correction is then performed, and the process jumps to step S60 to iterate and test the frequency-temperature characteristic curve of the isothermal crystal oscillator and the compensation branch parameter R. B1 R B2 R B3 The correction is made until the frequency-temperature characteristic curve meets the set requirements.

[0034] A third aspect of the present invention provides an electronic device comprising:

[0035] At least one processor;

[0036] and a memory communicatively connected to at least one of the processors;

[0037] The memory stores instructions that can be executed by the processor to implement the constant temperature point compensation method of the precision temperature control circuit described above.

[0038] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer instructions for execution by a computer to implement the above-described method for temperature compensation at a constant temperature point in a precision temperature control circuit.

[0039] The above-described at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0040] (1) The constant temperature point temperature compensation device of the precision temperature control circuit of the present invention can significantly improve the temperature control accuracy by simply replacing the original fixed resistor with a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network without changing the existing constant temperature structure, so that the constant temperature crystal oscillator can obtain excellent frequency and temperature stability.

[0041] (2) The constant temperature point compensation device of the precision temperature control circuit of the present invention adopts the constant temperature point compensation method, which can significantly improve the frequency and temperature stability of the constant temperature crystal oscillator. Experimental verification shows that by adopting constant temperature point compensation, the frequency and temperature stability of the single-layer temperature-controlled constant temperature crystal oscillator can be improved from 1E-8 to 1E-9, an improvement of one order of magnitude; and the frequency and temperature stability of the double-layer temperature-controlled constant temperature crystal oscillator can be improved from 5E-10 to 5E-11. Attached Figure Description

[0042] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0043] Figure 1 This is a schematic diagram of the proportional-integral temperature control circuit in the prior art;

[0044] Figure 2 A schematic diagram of the proportional-integral temperature control circuit principle of the constant temperature point compensation device for the precision temperature control circuit provided in one embodiment of this specification.

[0045] Figure 3 This is a schematic diagram of the constant temperature point compensation network principle of the constant temperature point compensation device for a precision temperature control circuit provided in one embodiment of this specification. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This invention relates to a precision temperature control circuit for a cryogenic crystal oscillator. By employing a cryogenic point compensation method, it improves temperature control capability and achieves higher temperature control accuracy, thereby enabling the cryogenic crystal oscillator to obtain higher frequency temperature stability. We propose a cryogenic point compensation method. By using this method, the temperature migration at the cryogenic point can be reduced or even eliminated, further improving the temperature control accuracy of the precision temperature control circuit and significantly improving the frequency temperature stability of the cryogenic crystal oscillator.

[0048] The technical solutions provided by the various embodiments of this application are described in detail below with reference to the accompanying drawings.

[0049] The first embodiment of the present invention, as follows: Figure 2The diagram shown is a schematic diagram of the proportional-integral temperature control circuit of the constant temperature point compensation device of the precision temperature control circuit provided in an embodiment of this specification. The precision temperature control circuit of the constant temperature crystal oscillator is composed of three operational amplifiers. The first-stage main temperature control circuit is a proportional-integral temperature control circuit, which is composed of three parts: operational amplifier N1, feedback loops Cf and Rf, and temperature control bridge.

[0050] The first and second output terminals of the temperature control bridge are respectively connected to the first and second input terminals of the operational amplifier. The first output terminal of the temperature control bridge and the first input terminal of the operational amplifier are connected to the first connection terminal of the feedback network, and the second connection terminal of the feedback network is connected to the output terminal of the operational amplifier.

[0051] The compensation branch is located in the constant temperature zone of the precision temperature control circuit. The temperature of the compensation branch is lower than the preset value of the constant temperature point but higher than the ambient temperature.

[0052] The temperature control branch is a proportional-integral (PI) temperature control circuit, which includes fixed resistors R1, R3, R4, and R5, and a thermistor R. T And the compensation branch, which is a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network.

[0053] The input terminal of the fixed resistor R1 is connected together with the input terminal of the compensation branch to serve as the input terminal of the temperature control bridge;

[0054] The output terminal of the fixed resistor R1 is connected to the thermistor R T After the input terminal is connected, it is connected together with the input terminal of the fixed resistor R4;

[0055] After the output terminal of the compensation branch is connected to the input terminal of the fixed resistor R3, it is then connected to the input terminal of the fixed resistor R5.

[0056] Thermistor R T The output terminal of is grounded and the output terminal of fixed resistor R3 are grounded respectively;

[0057] The output terminal of the fixed resistor R4 is used as the first output terminal of the temperature control bridge.

[0058] The output terminal of the fixed resistor R5 serves as the second output terminal of the temperature control bridge.

[0059] With negative temperature coefficient thermistor R TB or negative temperature coefficient thermistor network R TB The fixed resistor R2 (i.e., the one attached) in the precision temperature control circuit that replaces the oven-controlled crystal oscillator Figure 1 To ensure that the resistance R2 in the constant temperature point changes little or not at all, R must be... TB It remains essentially unchanged when the external ambient temperature changes.TB If V remains unchanged, then - =R TB *E / (R1+R TB The external ambient temperature remains unchanged. However, ΔU will change when the ambient temperature changes. And ΔU = V - -V + V - To change ΔU while keeping it constant, we can only change V. + Changes occur. By designing a circuit, V... + If a predetermined change occurs, V- can be guaranteed to remain unchanged (or change very little), i.e., R. TB It remains unchanged, meaning the isothermal point remains unchanged.

[0060] Compensation using negative temperature coefficient thermistor R TB or negative temperature coefficient thermistor network R TB Temperature T R Slightly below the isothermal point temperature, but above the ambient temperature. When the ambient temperature changes from low to high, the negative temperature coefficient thermistor R... TB or negative temperature coefficient thermistor network R TB The resistance value decreases as it changes, and its relationship with ambient temperature is shown in equation (1):

[0061] R TB =R TB0 [exp(B(1 / (273+T R )-1 / (273+T0)))] (1)

[0062] Where T0 is the ambient temperature, R TB0 B is the resistance of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network at room temperature, and T is the thermistor constant of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network. R To compensate for the temperature at the location of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network, R TB It refers to the resistance of a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network as the ambient temperature changes.

[0063] The voltage difference between the positive and negative terminals of the operational amplifier is shown in equation (2):

[0064] ΔU= V--V + (2)

[0065] Where ΔU is the voltage difference between the positive and negative terminals of the operational amplifier, V- is the voltage at the negative terminal of the operational amplifier, and V + This is the voltage at the positive terminal of the operational amplifier.

[0066] The mapping relationship between the voltage at the positive terminal of the operational amplifier and the negative temperature coefficient thermistor or the negative temperature coefficient thermistor network is shown in equation (3):

[0067] V + = R3*E / (R TB +R3) (3)

[0068] Where R3 is the resistance value of the third resistor in the temperature compensation branch, and E is the input level of the temperature compensation branch.

[0069] From the above, we can see that V + =R3*E / (R TB +R3) increases from small to large, which ensures that V - Under the condition that the remainder is essentially unchanged, ΔU = V - V + The heating power W decreases from large to small. J The value decreases as the ambient temperature rises, which is related to the heat dissipation power (W). S Maintaining balance.

[0070] The second embodiment of the present invention, as follows: Figure 3 The diagram shown is a schematic diagram of the constant temperature point compensation network principle of the constant temperature point compensation device of the precision temperature control circuit provided in one embodiment of this specification, including the compensation branch resistor R. TB Fixed resistor R B1 Fixed resistor R B2 Fixed resistor R B3 :

[0071] Compensation branch resistance R TB The input terminal and the fixed resistor R B1 The input terminals are connected together as the input terminal E of the isothermal point compensation network;

[0072] Compensation branch resistance R TB The output terminal is connected to a fixed resistor R. B2 The input terminal;

[0073] Fixed resistor R B1 The output terminal is connected to the fixed resistor R B2 The output terminals are connected together to a fixed resistor R. B3 The input terminal;

[0074] Fixed resistor R B3 The output terminal is used as the output terminal of the constant temperature point compensation network.

[0075] Based on the above-mentioned constant temperature point temperature compensation device for the precision temperature control circuit, the constant temperature point temperature compensation method of the precision temperature control circuit of the present invention includes:

[0076] Step S10: At room temperature, set the resistance of the precision resistance box of the temperature compensation device to R0, and after the frequency of the precision temperature control circuit stabilizes, obtain the output frequency F0 of the constant temperature crystal oscillator.

[0077] Step S20: Reduce the temperature of the precision resistance box to the lowest value T within its operating temperature range. L After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. L ;

[0078] The temperature of the precision resistance box is raised to the highest value T in its operating temperature range. H After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. H ;

[0079] Step S30, obtain the ambient temperature as T L T0, T H At that time, the compensation branch resistance R TB The corresponding actual temperature T RL T R0 T RH ;

[0080] Step S40, based on the external temperature T L T0, T H and compensation branch resistance R TB The actual temperature T RL T R0 T RH The corresponding precision resistor box resistance value R L R0, R H Obtain the compensation branch parameters R B1 R B2 R B3 ;

[0081] Step S50, based on the compensation branch parameters R B1 R B2 R B3 Configure compensation branches to achieve constant temperature compensation at the constant temperature point of the precision temperature control circuit.

[0082] In step S50, based on the compensation branch parameter R B1 R B2 R B3 After configuring the compensation branch, the compensation branch parameter R is also set. B1 R B2 R B3The fine-tuning steps are as follows:

[0083] Step S60, to compensate branch parameters R B1 R B2 R B3 Configure the compensation branch and test the frequency-temperature characteristic curve of the cryogenic crystal oscillator;

[0084] Step S70: Calculate the compensation branch parameter R based on the frequency-temperature characteristic curve. B1 R B2 R B3 The correction is then performed, and the process jumps to step S60 to iterate and test the frequency-temperature characteristic curve of the isothermal crystal oscillator and the compensation branch parameter R. B1 R B2 R B3 The correction is made until the frequency-temperature characteristic curve meets the set requirements.

[0085] A third embodiment of the present invention provides an electronic device comprising:

[0086] At least one processor;

[0087] and a memory communicatively connected to at least one of the processors;

[0088] The memory stores instructions that can be executed by the processor to implement the constant temperature point compensation method of the precision temperature control circuit described above.

[0089] A fourth embodiment of the present invention provides a computer-readable storage medium storing computer instructions, which are executed by the computer to implement the above-described method for temperature compensation at a constant temperature point in a precision temperature control circuit.

[0090] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for compensating the constant temperature point of a precision temperature control circuit, characterized in that, A constant-temperature point temperature compensation device based on a precision temperature control circuit, comprising a feedback network, an operational amplifier, and a temperature control bridge. The first and second output terminals of the temperature-controlled bridge are respectively connected to the first and second input terminals of the operational amplifier. The first output terminal of the temperature-controlled bridge and the first input terminal of the operational amplifier are connected to the first connection terminal of the feedback network. The second connection terminal of the feedback network is connected to the output terminal of the operational amplifier. The temperature-controlled bridge includes a temperature-controlled branch and a compensation branch. The temperature control branch is a proportional-integral (PI) temperature control circuit, which includes fixed resistors R1, R3, R4, and R5, and a thermistor R. T , The compensation branch is located in the constant temperature region of the precision temperature control circuit. The input terminal of the fixed resistor R1 is connected to the input terminal of the compensation branch as the input terminal of the temperature control bridge; the output terminal of the fixed resistor R1 is connected to the thermistor R T After the input terminal of the compensation branch is connected, it is connected together with the input terminal of the fixed resistor R4; after the output terminal of the compensation branch is connected to the input terminal of the fixed resistor R3, it is connected together with the input terminal of the fixed resistor R5; the thermistor R T The output terminal of the fixed resistor R4 is grounded, and the output terminal of the fixed resistor R5 is grounded. The output terminal of the fixed resistor R4 serves as the first output terminal of the temperature control bridge. The temperature of the compensation branch is lower than the preset value of the constant temperature point, but higher than the ambient temperature. The compensation branch is a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network. The mapping relationship between the negative temperature coefficient thermistor or negative temperature coefficient thermistor network and ambient temperature is as follows: R TB =R TB0 [exp(B(1 / (273+T R )-1 / (273+T0)))] Where T0 is the ambient temperature, R TB0 B is the resistance of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network at room temperature, and T is the thermistor constant of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network. R To compensate for the temperature at the location of the negative temperature coefficient thermistor or negative temperature coefficient thermistor network, R TB The resistance of a negative temperature coefficient thermistor or a negative temperature coefficient thermistor network after the ambient temperature changes. The voltage difference between the positive and negative terminals of the operational amplifier is: ΔU= V - -V + Where ΔU is the voltage difference between the positive and negative terminals of the operational amplifier, V - V is the voltage at the negative terminal of the operational amplifier. + This is the voltage at the positive terminal of the operational amplifier; The mapping relationship between the voltage at the positive terminal of the operational amplifier and the negative temperature coefficient thermistor or negative temperature coefficient thermistor network is as follows: In + = R3*E / (R TB +R3) Where R3 is the resistance value of the third resistor in the temperature compensation branch, and E is the input level of the temperature compensation branch. The constant temperature point temperature compensation method includes: Step S10: At room temperature, set the resistance of the precision resistance box of the constant temperature point temperature compensation device to R0, and after the frequency of the precision temperature control circuit stabilizes, obtain the output frequency F0 of the constant temperature crystal oscillator. Step S20: Reduce the temperature of the precision resistance box to the lowest value T within its operating temperature range. L After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. L ; The temperature of the precision resistance box is raised to the highest value T in its operating temperature range. H After the frequency of the oven-controlled crystal oscillator stabilizes, the resistance of the precision resistor box is finely adjusted so that the output frequency of the oven-controlled crystal oscillator stabilizes at F0, and the corresponding resistance value R of the precision resistor box is obtained. H ; Step S30, obtain the ambient temperature as T L T0, T H At that time, the compensation branch resistance R TB The corresponding actual temperature T RL T R0 T RH ; Step S40, based on the external temperature T L T0, T H and compensation branch resistance R TB The actual temperature T RL T R0 T RH The corresponding precision resistor box resistance value R L R0, R H Obtain the compensation branch parameters R B1 R B2 R B3 ; Step S50, based on the compensation branch parameters R B1 R B2 R B3 Configure compensation branches to achieve constant temperature compensation at the constant temperature point of the precision temperature control circuit.

2. The method for compensating the constant temperature point of the precision temperature control circuit according to claim 1, characterized in that, In step S50, based on the compensation branch parameter R B1 R B2 R B3 After configuring the compensation branch, the compensation branch parameter R is also set. B1 R B2 R B3 The fine-tuning steps are as follows: Step S60, to compensate branch parameters R B1 R B2 R B3 Configure the compensation branch and test the frequency-temperature characteristic curve of the cryogenic crystal oscillator; Step S70: Calculate the compensation branch parameter R based on the frequency-temperature characteristic curve. B1 R B2 R B3 The correction is then performed, and the process jumps to step S60 to iterate and test the frequency-temperature characteristic curve of the isothermal crystal oscillator and the compensation branch parameter R. B1 R B2 R B3 The correction is made until the frequency-temperature characteristic curve meets the set requirements.

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