CN116232229A - Temperature compensation method of temperature compensation crystal oscillator and crystal oscillator - Google Patents
Temperature compensation method of temperature compensation crystal oscillator and crystal oscillator Download PDFInfo
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- H—ELECTRICITY
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- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/02—Details
- H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
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- H03L1/00—Stabilisation of generator output against variations of physical values, e.g. power supply
- H03L1/02—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only
- H03L1/022—Stabilisation of generator output against variations of physical values, e.g. power supply against variations of temperature only by indirect stabilisation, i.e. by generating an electrical correction signal which is a function of the temperature
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Abstract
The invention belongs to the technical field of crystal oscillator design, and particularly discloses a temperature compensation method of a temperature compensation crystal oscillator and the crystal oscillator. The temperature compensation method comprises the following steps: measuring a working temperature signal of a crystal resonator in the temperature compensation crystal oscillator; generating a frequency control signal according to the working temperature signal and a predetermined target nominal frequency temperature curve, and controlling the oscillation frequency of the crystal resonator by using the frequency control signal; the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator by a polynomial compensation function generator. The invention solves the problem that the compensation precision of temperature compensation is still lower in the related art.
Description
Technical Field
The invention belongs to the technical field of crystal oscillator design, and particularly relates to a temperature compensation method of a temperature compensation crystal oscillator and the crystal oscillator.
Background
Quartz crystal is a kind of anisotropic crystal, and a crystal oscillator providing stable frequency signal can be designed by utilizing the piezoelectric effect of quartz crystal. The crystal oscillator made of the common AT cut quartz crystal also has frequency variation of tens ppm when the ambient temperature is changed, and in order to realize higher frequency temperature stability, temperature compensation is also needed.
Depending on the resonant mode of the crystal resonator, series connection of the crystal resonator to a reactor causes a shift in the crystal resonant frequency. If a variable reactor is used and the reactance value varies inversely with the frequency offset of the resonator in the event of a temperature change, the frequency offset can be reduced and the temperature coefficient can be greatly improved. Therefore, a method of connecting varactors in series in a crystal resonator branch can be adopted, and the oscillation frequency can be adjusted by changing the reactance value according to the change of temperature. The equation of the frequency temperature characteristic equation of the quartz resonator plus the compensation voltage on the varactor is shown as follows:
wherein T is-any temperature, in units of DEG C; t (T) 0 -a reference temperature in degrees celsius; f-oscillation frequency, in Hz; f (f) 0 -a reference frequency in Hz; a, a 0 -reference temperature T 0 The first-order temperature coefficient is 1/DEGC; b 0 -a second order temperature coefficient in 1/°c 2 at a reference temperature T0; c 0 -at a reference temperature T 0 The three-stage temperature coefficient is 1/. Degree.C.3. a-dynamic temperature coefficient, a=10-5 s/°c; the voltage control coefficient of the KV-varactor is Hz/V; UK-control voltage applied across the varactor.
In the prior art, a function generator is integrated in an IC of a temperature compensation crystal oscillator TCXO to compensate the frequency-temperature offset of a crystal, and particularly, the value of a register of the function generator is changed to change each sub-term coefficient of the function generator, so as to generate a frequency compensation curve complementary with the frequency-temperature characteristic of a resonator, obtain a nominal frequency-temperature curve, automatically generate corresponding control voltage, control a varactor diode in the crystal oscillator, change the load capacitance of the crystal, pull the frequency of the crystal oscillator, and achieve the effect of temperature compensation, thereby compensating the frequency according to the nominal frequency-temperature curve when the temperature changes, adjusting the change of the frequency of the crystal oscillator, and achieving the purpose of stable output of the frequency of the crystal oscillator.
Disclosure of Invention
The invention aims to provide a temperature compensation method of a temperature compensation crystal oscillator and the crystal oscillator, so as to solve the problem that the compensation precision of temperature compensation in the related art is still lower.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a temperature compensation method of a temperature compensated crystal oscillator having a polynomial compensation function generator integrated therein, the method comprising:
measuring a working temperature signal of a crystal resonator in the temperature compensation crystal oscillator;
generating a frequency control signal according to the working temperature signal and a predetermined target nominal frequency temperature curve, and controlling the oscillation frequency of the crystal resonator by using the frequency control signal; the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator by the polynomial compensation function generator.
Further, the step of obtaining the target nominal frequency temperature curve by adding a linear compensation line segment to the initial nominal frequency temperature curve of the crystal resonator to perform linear compensation comprises the following steps:
dividing the initial nominal frequency temperature curve into a plurality of frequency temperature curve sections according to a preset temperature section, respectively adding a linear compensation line section to each frequency temperature curve section in the corresponding temperature section, wherein the change trend of the linear compensation line section is opposite to that of the frequency temperature curve section, so that the corresponding frequency temperature curve sections are respectively subjected to linear compensation by utilizing each linear compensation line section, and the target nominal frequency temperature curve is obtained.
Further, the composition parameters of the linear compensation line segment include:
zero bias temperature, wherein the zero bias temperature is a temperature value selected from temperature values in the temperature section when the frequency compensation quantity of the initial nominal frequency temperature curve is zero;
the slope of the line segment is obtained according to a preset slope value range.
Further, the composition parameters of the linear compensation line segment include:
zero offset temperature, wherein the zero offset temperature is a temperature value selected from a plurality of temperature values in the corresponding temperature section when the frequency compensation amount of the linear compensation line segment to the initial nominal frequency temperature curve is zero;
the slope of the line segment is obtained according to a preset slope value range;
then, before the linear compensation is performed on the corresponding frequency temperature curve segment by using each linear compensation line segment, the method further includes:
for each linear compensation line segment, according to the selected temperature value and the slope value range of the line segment slope, adjusting the zero offset temperature and the line segment slope to obtain a plurality of preselected linear compensation line segments;
and selecting a target linear compensation line segment from a plurality of pre-selected linear compensation line segments so as to perform linear compensation on the corresponding frequency temperature curve segment by utilizing the target linear compensation line segment.
Further, the step of adjusting the zero offset temperature and the slope of the line segment to obtain a plurality of preselected linear compensation line segments according to the selected temperature value and the slope value range of the slope of the line segment comprises:
and when the zero offset temperature selects different temperature values, selecting different slope values from the slope value range as the line segment slopes to obtain a plurality of preselected linear compensation line segments.
In a second aspect of the present invention, there is provided a temperature compensated crystal oscillator for temperature compensation by a temperature compensation method of the temperature compensated crystal oscillator, the temperature compensated crystal oscillator comprising:
the control chip comprises a polynomial compensation function generator;
the crystal resonator is electrically connected with the control chip;
the control chip is used for measuring a working temperature signal of the crystal resonator, controlling the polynomial compensation function generator to generate a frequency control signal according to the working temperature signal and a predetermined target nominal frequency temperature curve, and controlling the oscillation frequency of the crystal resonator by utilizing the frequency control signal, wherein the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator by the polynomial compensation function generator.
Further, the control chip further includes:
the temperature sensor is used for measuring the working temperature signal of the crystal resonator in the temperature compensation crystal oscillator;
and one end of the oscillation control module is electrically connected with the polynomial compensation function generator, and the other end of the oscillation control module is electrically connected with the crystal resonator.
Further, the oscillation control module includes:
one end of the varactor is electrically connected with the polynomial compensation function generator;
and the oscillating circuit is electrically connected between the varistors and the crystal resonator.
Further, the polynomial compensation function generator includes:
the temperature coefficient compensation unit is electrically connected with the output end of the temperature sensor;
the linear compensation unit is electrically connected with the output end of the temperature sensor;
the input end of the adder is electrically connected with the output end of the temperature coefficient compensation unit and the output end of the linear compensation unit, and the output end of the adder is electrically connected with the oscillation control module.
Further, the control chip further includes:
and the shaping frequency dividing circuit is electrically connected with the oscillation control module.
Compared with the prior art, the technical scheme provided by the application has the following technical effects:
the temperature compensation method provided by the embodiment of the invention optimizes the temperature compensation effect in the prior art, can realize that the frequency temperature stability is better than +/-0.28 ppm within the range of-40 ℃ to +85 ℃, and meets the use requirements of electronic equipment on the continuous improvement of the miniaturization and high precision of the temperature compensation crystal oscillator.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a schematic diagram illustrating a temperature compensation method of a temperature compensated crystal oscillator according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a circuit structure of a temperature compensated crystal oscillator according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of frequency compensation according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a test flow of five-time temperature coefficient curve compensation according to an embodiment of the present invention;
FIG. 5 is a schematic diagram showing the influence of the numerical variation of several registers on the frequency temperature curve according to an embodiment of the present invention;
FIG. 6 is a diagram showing the influence of the numerical variation of the FIFTH register on the frequency temperature curve according to one embodiment of the present invention;
FIG. 7 is a schematic diagram showing exemplary effects of different values of zero offset temperature and line slope on a frequency curve according to an embodiment of the present invention;
fig. 8 is a schematic diagram of linear compensation according to an embodiment of the invention.
Reference numerals illustrate:
10. a temperature compensated crystal oscillator; 11. a control chip; 111. a temperature sensor; 112. a polynomial compensation function generator; 121. a temperature coefficient compensation unit; 122. a linear compensation unit; 123. an adder; 113. a varactor diode; 114. an oscillating circuit; 115. a shaping frequency dividing circuit; 12. a crystal resonator.
Detailed Description
The advantages and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings and detailed description. It should be noted that the drawings are in a very simplified form and are adapted to non-precise proportions, merely for the purpose of facilitating and clearly aiding in the description of embodiments of the invention.
It should be noted that, in order to clearly illustrate the present invention, various embodiments of the present invention are specifically illustrated by the present embodiments to further illustrate different implementations of the present invention, where the various embodiments are listed and not exhaustive. Furthermore, for simplicity of explanation, what has been mentioned in the previous embodiment is often omitted in the latter embodiment, and therefore, what has not been mentioned in the latter embodiment can be referred to the previous embodiment accordingly.
Referring to fig. 1, a temperature compensation method of a temperature compensated crystal oscillator 10 is provided according to a first embodiment of the present invention, wherein a polynomial compensation function generator 112 is integrated in the temperature compensated crystal oscillator 10, and the temperature compensation method provided by the embodiment of the present invention includes the following steps:
step S11: an operating temperature signal of the crystal resonator 12 in the temperature compensated crystal oscillator 10 is measured.
Step S12: generating a frequency control signal according to the working temperature signal and a predetermined target nominal frequency temperature curve, and controlling the oscillation frequency of the crystal resonator 12 by using the frequency control signal, wherein the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator 12 for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator 12 by the polynomial compensation function generator 112.
The polynomial compensation function generator 112 is internally provided with registers such as a FIFTH register, a FOUR register, a CUB register, an INF register, a LIN register, etc., and each term coefficient of the polynomial compensation function generator 112 is controlled by changing the numerical value of each register to generate an initial nominal frequency temperature curve (i.e. a compensated frequency curve in fig. 3) complementary with the frequency temperature characteristic of the crystal resonator 12, so as to achieve the effect of temperature compensation. On the basis of performing temperature compensation on the crystal resonator 12 according to the initial nominal frequency temperature curve, the embodiment of the invention also performs corresponding linear compensation on the crystal resonator 12, so that the frequency temperature stability of the crystal oscillator can be reduced from +/-1 ppm to +/-0.1 ppm to +/-0.2 ppm within the temperature range of-40 ℃ to +85 ℃, and the compensation level of the temperature compensation crystal oscillator 10 is greatly improved.
In one embodiment of the present invention, the step of obtaining the target nominal frequency temperature profile by adding a linear compensation line segment to the initial nominal frequency temperature profile of the crystal resonator 12 comprises: dividing an initial nominal frequency temperature curve into a plurality of frequency temperature curve sections according to a preset temperature section, respectively adding linear compensation line sections (shown as each broken line section in fig. 8) to each frequency temperature curve section in the corresponding temperature section, wherein the change trend of the linear compensation line sections is opposite to that of the frequency temperature curve sections, respectively carrying out linear compensation on the corresponding frequency temperature curve sections by utilizing each linear compensation line section, and superposing each linear compensation line section to the initial nominal frequency temperature curve according to the compensation influence of each linear compensation line section on the corresponding frequency temperature curve section to obtain a target nominal frequency temperature curve. When the initial nominal frequency temperature curve is subjected to piecewise linear compensation, the initial nominal frequency temperature curve can be divided into 8 temperature sections within the temperature range of-40 ℃ to +85 ℃, and one linear compensation amount EVA 0-EVA 7 is added in each temperature section, as shown in Table 1:
| compensation amount | Temperature range |
| EVA0 | -40℃～-35℃ |
| EVA1 | -35℃～-20℃ |
| EVA2 | -15℃～0℃ |
| EVA3 | 5℃～20℃ |
| EVA4 | 25℃～40℃ |
| EVA5 | 45℃～60℃ |
| EVA6 | 65℃～80℃ |
| EVA7 | 80℃～85℃ |
TABLE 1 temperature ranges for the temperature segments during piecewise Linear Compensation
Wherein, the constituent parameters of each linear compensation line segment include two parameters (the two parameters are set by the corresponding linear compensator integrated in the polynomial compensation function generator 112) of zero offset temperature, which is a temperature value selected from temperature values in the temperature segment when the frequency compensation amount for the initial nominal frequency temperature curve is zero, and in practical engineering, the zero offset temperature is limited by the configuration conditions of the linear compensator-related storage device in the linear compensation unit 122, and only an integer temperature value specified in each temperature segment can be selected, for example, for a temperature segment of-15 ℃ to 0 ℃ of the compensation amount EVA2, the zero offset temperature can be selected to have a temperature of-15 ℃, -10 ℃, -5 ℃, 0 ℃ and the like as integer values. The slope of the line segment is obtained according to a preset slope value range, for example, the slope of the line segment can be selected from-0.08 to +0.08 in steps with preset step values for a temperature range of-15 ℃ to 0 ℃ of the compensation quantity EVA2, for example, when the step value is 0.01, the slope of the line segment can be selected from-0.08, -0.07, -0.06, -0.05 to +0.08, and typical influences of different slope values on a frequency curve are shown in fig. 7.
Before each linear compensation line segment is utilized to perform linear compensation on a corresponding frequency temperature curve segment, the embodiment of the invention adjusts zero bias temperature and line segment slope according to the selected temperature value and slope value range of the line segment slope to obtain a plurality of preselected linear compensation line segments (different preselected linear compensation line segments obtained under different zero bias temperatures and line segment slope shown in fig. 7), and then selects a target linear compensation line segment from the plurality of preselected linear compensation line segments, thereby selecting a target linear compensation line segment with the best compensation effect, wherein the best compensation effect is one linear compensation line segment with the smallest frequency temperature stability ppm value when the temperature compensation crystal oscillator 10 changes at ambient temperature, so that the corresponding frequency temperature curve segment is subjected to linear compensation by utilizing the target linear compensation line segment. Wherein the step of adjusting the zero bias temperature and the slope of the line segment to obtain a plurality of preselected linear compensation line segments according to the selected temperature value and the slope value range of the slope of the line segment comprises: when the zero bias temperature selects different temperature values, different slope values are selected from a slope value range to serve as line slopes to obtain a plurality of pre-selected linear compensation line segments, for example, when the zero bias temperature is a specific value, the line slopes can be sequentially selected from-0.08 to +0.08 by taking a preset stepping value as a stepping step, for example, the zero bias temperature is-15 ℃, the line slope is selected to-0.07 to obtain one linear compensation line segment, when the line slope becomes-0.06, another linear compensation line segment is obtained, and the like, so as to obtain a plurality of different pre-selected linear compensation line segments, a zero bias temperature with better compensation precision for the corresponding frequency temperature curve segments and a proper parameter of the line slope are selected from the pre-selected linear compensation line segments, so that the target linear compensation line segment with the best compensation effect for each curve segment of the initial nominal frequency temperature curve is obtained, each frequency temperature curve segment obtained through testing is correspondingly overlapped to each frequency temperature curve segment of the initial nominal frequency temperature curve, the compensation of each frequency temperature curve segment is more accurate, when the crystal oscillator works, namely, the crystal oscillator can be reduced to the proper temperature within the temperature range of +1.12ppm by the corresponding frequency of the oscillator, and the crystal oscillator can be reduced to the current oscillation frequency of the crystal oscillator within the range of +1.12ppm, and the crystal oscillation frequency can be reduced by the current temperature range of the crystal oscillator is reduced by the temperature 2ppm within the temperature range of +12ppm.
In a second embodiment of the present invention, a temperature compensated crystal oscillator 10 is provided, the temperature compensated crystal oscillator 10 performs temperature compensation by using the temperature compensation method provided in the first embodiment, the temperature compensated crystal oscillator 10 includes a control chip 11 and a crystal resonator 12, the control chip 11 includes a polynomial compensation function generator 112, and the crystal resonator 12 is electrically connected to the control chip 11.
The control chip 11 is configured to measure an operating temperature signal of the crystal resonator 12, and control the polynomial compensation function generator 112 to generate a frequency control signal according to the operating temperature signal and a predetermined target nominal frequency temperature curve, and control an oscillation frequency of the crystal resonator 12 by using the frequency control signal, where the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator 12 to perform linear compensation, and the initial nominal frequency temperature curve is obtained by compensating a frequency offset of the crystal resonator 12 by the polynomial compensation function generator 112.
The control chip 11 further includes a temperature sensor 111 and an oscillation control module, the temperature sensor 111 is used for measuring a working temperature signal of the crystal resonator 12 in the temperature compensation crystal oscillator 10, then the working temperature signal is input into the polynomial compensation function generator 112, the oscillation control module includes a varactor and an oscillation circuit 114, the varactor in the embodiment of the invention is a varactor 113, one end of the varactor 113 is electrically connected with the polynomial compensation function generator 112, the other end is electrically connected with the oscillation circuit 114, the oscillation circuit 114 is electrically connected between the varactor 113 and the crystal resonator 12, and the oscillation circuit 114 is used for enabling the crystal resonator 12 to generate an oscillation signal.
The temperature coefficient compensation unit 121 is electrically connected to the output end of the temperature sensor 111, and as the frequency temperature curves of different crystal resonators 12 have large differences, in order to adapt to different crystal resonators 12, registers such as a FIFTH register, a FOUR register, a CUB register, an INF register, a LIN register and the like are arranged in the temperature coefficient compensation unit 121, and in the stage of determining the initial nominal frequency temperature curve, the coefficients of the polynomial compensation function generator 112 are controlled by changing the numerical value of each register to generate the initial nominal frequency temperature curve complementary to the initial frequency temperature characteristics of the crystal resonators 12, and the compensation parameters of each register are obtained, so that in the actual working process of the temperature compensated crystal oscillator 10, the coefficients of the polynomial compensation function generator 112 are changed by the compensation parameters of each register according to the initial nominal frequency temperature curve, the control voltage is generated to change the capacitance of the varactor diode 113, and further change the frequency of the load of the crystal resonator 12, so as to achieve the temperature compensation effect of the load of the crystal resonator 12.
The linear compensation unit 122 is electrically connected to the output end of the temperature sensor 111, and the linear compensation unit 122 is configured to provide the formation parameters of the linear compensation line segment in the corresponding temperature segment range and output the compensation signal according to the formation parameters in the determining stage of the target nominal frequency temperature curve and the actual working stage of the temperature compensated crystal oscillator 10, according to the content of table 1, the linear compensation unit 122 is provided with a plurality of linear compensators (N in the linear compensators N is a positive integer in fig. 2, N is equal to seven when eight linear compensators are used) according to the set plurality of linear compensators (N is a positive integer) respectively, each linear compensator generates a corresponding compensation signal (each linear compensator outputs the compensation signal only in the temperature segment required by each temperature segment, if the current working environment temperature is within the temperature range where the compensation amount EVA2 is located, only the linear compensator 3 outputs the voltage signal, and the other linear compensators output zero according to the content of table 1, and meanwhile, each linear compensator in the temperature coefficient compensation unit 121 outputs the voltage signal according to the set plurality of linear compensators N, so that the temperature coefficient unit 121 further compensates the resonance frequency of the crystal 12. The input end of the adder 123 is electrically connected with the output end of the temperature coefficient compensation unit 121 and the output end of the linear compensation unit 122, the output end of the adder 123 is electrically connected with the oscillation control module, and the adder 123 outputs the voltage signals for compensation processing output by the temperature coefficient compensation unit 121 and the linear compensation unit 122 after superposition. Thus, in the embodiment of the present invention, the temperature sensor 111 is used to receive a temperature signal, based on a target nominal frequency temperature curve of the crystal resonator 12, on the basis of changing each order coefficient of the polynomial compensation function generator 112 through a register, further linearly compensating the frequency offset of the crystal resonator 12 through a linear compensator, generating a corresponding control voltage (i.e. a frequency control signal), changing the capacitance of the varactor 113, further changing the load capacitance of the crystal resonator 12, and pulling the output frequency of the crystal resonator. In addition, the control chip 11 further includes a shaping frequency-dividing circuit 115, and the shaping frequency-dividing circuit 115 is electrically connected to the oscillating circuit 114, for adjusting the amplitude of the oscillating signal output by the temperature compensated crystal oscillator.
In the embodiment of the present invention, the principle of compensating the frequency offset of the crystal resonator 12 by the polynomial compensation function generator 112 is shown in fig. 8, in which the uncompensated frequency curve is an uncompensated original frequency curve of the crystal resonator 12, the dashed line is a compensated frequency curve, the compensated frequency curve is an initial nominal frequency temperature curve, and when the temperature changes to change the oscillation frequency of the crystal oscillator, the change trend of the compensated frequency is opposite to the change trend of the oscillation frequency of the crystal oscillator, so that the oscillation frequency of the crystal oscillator is pulled to change in the opposite direction. When two effects of temperature and frequency compensation are simultaneously applied to the crystal oscillator and the two effects have a considerable influence on the oscillation frequency of the crystal oscillator, the oscillation frequency of the crystal oscillator is stabilized at the nominal frequency. The frequency compensation can be compensated when the temperature changes as long as the rule of the frequency compensation along with the temperature change is determined, and the change of the crystal oscillator frequency is adjusted, so that the purpose of stable output of the crystal oscillator frequency is achieved. In this regard, the initial nominal frequency temperature profile in the present embodiment is obtained by testing the temperature compensated crystal oscillator 10 as follows:
the temperature compensation parameter analysis flow is shown in fig. 4, firstly, the temperature of the incubator is set, after the temperature is stable, the initial value of each register is set, the frequency corresponding to the initial register is tested, then the value of each register is changed in sequence, each register is changed, the corresponding frequency is tested once, when the next register is changed, the value of the register which is changed before is restored to the initial value, more than ten temperature points are completed in the whole temperature range to acquire the corresponding frequency value, and the frequency of crystal oscillator output after each register is changed is recorded.
In the compensation test, if each register is respectively increased by 20 and the frequency temperature curve corresponding to the temperature compensation crystal oscillator 10 is tested after the temperature compensation crystal oscillator is decreased by 20, each curve is subtracted from the curve corresponding to the initial value of the temperature compensation crystal oscillator, the influence amount of the change of each register on the frequency temperature curve can be obtained, as shown in fig. 5 and 6, in the curve corresponding to each register, one line is the influence amount of the increase of 20 of the register, the other line is the influence amount of the decrease of 20 of the register, for example, in the graph of the influence amount of the frequency temperature curve of the LIN register, LIN is the influence amount of the increase of 20 of the LIN register, +LIN is the influence amount of the decrease of 20 of the LIN register, if the value of the LIN register is still insufficient to be increased on the basis of the initial curve by calculating the value of the present LIN register, the system will continuously increase the value of the LIN register until one term of the temperature curve is counteracted, the value of the LIN register obtained at this time is used as the optimal value of the register, the value of the INF register is still not enough to be increased by 20 on the basis of the original curve by calculating the value of the present INF register, the system will continuously increase the value of the INF register until the quadratic term of the temperature curve is counteracted, and so on, the three times of the term of the original temperature curve of the crystal resonator 12 is counteracted by changing the value of the CUB register, the FOUR times of the term of the original temperature curve is counteracted by changing the FOUR register, the five times of the term of the original temperature curve is counteracted by changing the FIFTH register, the compensation parameters of the five registers are finally obtained, and then the compensation frequency curve represented by the dotted line in fig. 3 or 8 is obtained by fitting calculation (for example, fitting the influence quantity of the frequency temperature curve of each register by adopting the least square method), and superposing the compensated frequency curve and the uncompensated frequency curve according to the proportion controlled by the numerical control register, so as to obtain an initial nominal frequency temperature curve (namely the frequency curve after compensation in fig. 3 and 8) meeting the frequency temperature stability.
On the basis of the initial nominal frequency temperature curve obtained by the five-time temperature curve compensation, the frequency temperature stability of the crystal oscillator can be generally controlled to be about +/-1 ppm within the temperature range of-40 ℃ to +85 ℃, as shown by the compensated frequency curve in fig. 8.
In order to further optimize the frequency temperature stability of the temperature compensated crystal oscillator, the embodiment of the invention tests every 5 ℃ in the full temperature range to test a complete initial nominal frequency temperature curve. Dividing the temperature curve into 8 temperature sections at-40 to +85 ℃, and adding one linear compensation quantity EVA 0-EVA 7 into each temperature section.
Each compensation amount is a compensation line segment comprising two parameters of zero bias temperature (the temperature corresponding to zero compensation amount of the initial nominal frequency temperature curve) and slope, taking EVA2 as an example, for the test condition in the range of-15 ℃ to 0 ℃, by changing the two parameters of zero bias temperature and slope, the zero bias temperature can be selected from the values of-15 ℃, 10 ℃ and-5 ℃ and 0 ℃, the slope can be selected from the values of-0.08 to +0.08 by taking 0.01 as a step, and the typical influence of different values on the frequency curve is shown in fig. 7. According to the test result of the first step compensation, proper parameters of zero bias temperature and slope (shown as broken line segments in fig. 8) are selected and superimposed on the compensated frequency curve, so that the compensation of each temperature segment is more accurate, a higher compensation effect is achieved, the frequency temperature stability of the crystal oscillator can be reduced from +/-1 ppm to +/-0.1 ppm to +/-0.2 ppm within the temperature range of-40 ℃ to +85 ℃, and the compensation level of the temperature compensation crystal oscillator is greatly improved.
Therefore, the temperature compensation method provided by the embodiment of the invention optimizes the temperature compensation effect in the prior art, can realize that the frequency temperature stability is better than +/-0.28 ppm within the range of-40 ℃ to +85 ℃, and meets the use requirements of electronic equipment on the continuous improvement of the miniaturization and high precision of the temperature compensation crystal oscillator 10.
Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
In addition, the terms "first", "second", etc. are used to define the components, and are merely for convenience of distinguishing the corresponding components, and unless otherwise stated, the terms have no special meaning, and thus should not be construed as limiting the scope of the present application.
The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (10)
1. A temperature compensation method of a temperature compensated crystal oscillator, wherein a polynomial compensation function generator (112) is integrated into the temperature compensated crystal oscillator (10), the method comprising:
measuring an operating temperature signal of a crystal resonator (12) in a temperature compensated crystal oscillator (10);
generating a frequency control signal based on the operating temperature signal and a predetermined target nominal frequency temperature profile, and controlling an oscillation frequency of the crystal resonator (12) using the frequency control signal; the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator (12) for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator (12) by the polynomial compensation function generator (112).
2. A temperature compensation method of a temperature compensated crystal oscillator (10) as claimed in claim 1 wherein the step of obtaining the target nominal frequency temperature profile by adding a linear compensation line segment to the initial nominal frequency temperature profile of the crystal resonator (12) comprises:
dividing the initial nominal frequency temperature curve into a plurality of frequency temperature curve sections according to a preset temperature section, respectively adding a linear compensation line section to each frequency temperature curve section in the corresponding temperature section, wherein the change trend of the linear compensation line section is opposite to that of the frequency temperature curve section, so that the corresponding frequency temperature curve sections are respectively subjected to linear compensation by utilizing each linear compensation line section, and the target nominal frequency temperature curve is obtained.
3. The method for temperature compensation of a temperature compensated crystal oscillator of claim 2, wherein the composition parameters of the linear compensation line segment comprise:
zero bias temperature, wherein the zero bias temperature is a temperature value selected from temperature values in the temperature section when the frequency compensation quantity of the initial nominal frequency temperature curve is zero;
the slope of the line segment is obtained according to a preset slope value range.
4. The method for temperature compensation of a temperature compensated crystal oscillator of claim 2, wherein the composition parameters of the linear compensation line segment comprise:
zero offset temperature, wherein the zero offset temperature is a temperature value selected from a plurality of temperature values in the corresponding temperature section when the frequency compensation amount of the linear compensation line segment to the initial nominal frequency temperature curve is zero;
the slope of the line segment is obtained according to a preset slope value range;
then, before the linear compensation is performed on the corresponding frequency temperature curve segment by using each linear compensation line segment, the method further includes:
for each linear compensation line segment, according to the selected temperature value and the slope value range of the line segment slope, adjusting the zero offset temperature and the line segment slope to obtain a plurality of preselected linear compensation line segments;
and selecting a target linear compensation line segment from a plurality of pre-selected linear compensation line segments so as to perform linear compensation on the corresponding frequency temperature curve segment by utilizing the target linear compensation line segment.
5. The method of temperature compensation of a temperature compensated crystal oscillator of claim 4 wherein the step of adjusting the zero offset temperature and the slope of the line segment to obtain a plurality of preselected linear compensation line segments based on the selected temperature value and the slope range of the slope of the line segment comprises:
and when the zero offset temperature selects different temperature values, selecting different slope values from the slope value range as the line segment slopes to obtain a plurality of preselected linear compensation line segments.
6. A temperature compensated crystal oscillator, wherein the temperature compensated crystal oscillator (10) performs temperature compensation by using the temperature compensation method of the temperature compensated crystal oscillator (10) according to any one of claims 1 to 5, and the temperature compensated crystal oscillator (10) comprises:
a control chip (11), the control chip (11) comprising a polynomial compensation function generator (112);
a crystal resonator (12), the crystal resonator (12) being electrically connected to the control chip (11);
the control chip (11) is used for measuring an operating temperature signal of the crystal resonator (12), controlling the polynomial compensation function generator (112) to generate a frequency control signal according to the operating temperature signal and a predetermined target nominal frequency temperature curve, and controlling the oscillation frequency of the crystal resonator (12) by utilizing the frequency control signal, wherein the target nominal frequency temperature curve is obtained by adding a linear compensation line segment to an initial nominal frequency temperature curve of the crystal resonator (12) for linear compensation, and the initial nominal frequency temperature curve is obtained by compensating the frequency offset of the crystal resonator (12) by the polynomial compensation function generator (112).
7. The temperature compensated crystal oscillator (10) of claim 6, wherein the control chip (11) further comprises:
a temperature sensor (111) for measuring an operating temperature signal of a crystal resonator (12) in the temperature compensated crystal oscillator (10);
and one end of the oscillation control module is electrically connected with the polynomial compensation function generator (112), and the other end of the oscillation control module is electrically connected with the crystal resonator (12).
8. The temperature compensated crystal oscillator (10) of claim 7, wherein the oscillation control module comprises:
a varactor, one end of which is electrically connected with the polynomial compensation function generator (112);
-an oscillating circuit (114), said oscillating circuit (114) being electrically connected between said varactor and said crystal resonator (12).
9. The temperature compensated crystal oscillator (10) of claim 7, wherein the polynomial compensation function generator (112) comprises:
a temperature coefficient compensation unit (121), wherein the temperature coefficient compensation unit (121) is electrically connected with the output end of the temperature sensor (111);
a linear compensation unit (122), wherein the linear compensation unit (122) is electrically connected with the output end of the temperature sensor (111);
and the input end of the adder (123) is electrically connected with the output end of the temperature coefficient compensation unit (121) and the output end of the linear compensation unit (122), and the output end of the adder (123) is electrically connected with the oscillation control module.
10. The temperature compensated crystal oscillator (10) of claim 7, wherein the control chip (11) further comprises:
and the shaping frequency dividing circuit (115), and the shaping frequency dividing circuit (115) is electrically connected with the oscillation control module.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117097288A (en) * | 2023-10-19 | 2023-11-21 | 麦斯塔微电子(深圳)有限公司 | Dual-mode resonance device, dual-output MEMS oscillator and temperature compensation method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117097288A (en) * | 2023-10-19 | 2023-11-21 | 麦斯塔微电子(深圳)有限公司 | Dual-mode resonance device, dual-output MEMS oscillator and temperature compensation method |
| CN117097288B (en) * | 2023-10-19 | 2024-02-13 | 麦斯塔微电子(深圳)有限公司 | Dual-mode resonance device, dual-output MEMS oscillator and temperature compensation method |
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