JP2001036342A - Crystal oscillator with temperature compensation - Google Patents

Abstract

(57) [Problem] To provide a crystal oscillator with temperature compensation suitable for mass production, in which temperature-control voltage characteristics of each VCXO can be easily obtained. SOLUTION: A control table is constituted by a flash memory 4, and a four-point data input part 7 for inputting respective control voltage data for at least four different temperature data to a control part 6, and storing the four-point data. Point data storage unit 8, arithmetic unit 9 for calculating a cubic curve based on the four-point data, and cubic curve storage unit 10 for storing the cubic curve
And a control data writing unit 11 for calculating control voltage data corresponding to predetermined temperature data based on the cubic curve and writing the control voltage data to the flash memory, By inputting the control voltage data from the four-point data input unit, the control voltage data corresponding to the predetermined temperature data is written to the flash memory, so that only four temperatures need to be measured, thereby significantly reducing the manufacturing cost. Can.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator with temperature compensation, and more particularly to a crystal oscillator using an AT-cut VCXO and having a temperature-control voltage characteristic of the VCXO as a control table.

[0002]

2. Description of the Related Art A conventional crystal oscillator with temperature compensation is shown in FIG.
As shown in FIG. 1, an AT-cut VCXO (Voltage Controlled Crystal Oscillator) that controls the oscillation frequency by a control voltage
llator) 1, a temperature sensor 2 for detecting an ambient temperature, and A for converting a temperature signal from the temperature sensor 2 into temperature data.
/ D conversion unit 3 and the VCXO1 for the same temperature data.
A control table 4 'for storing control voltage data as a table for causing the oscillation of the oscillator to have a constant frequency, a D / A converter 5 for converting the control voltage data output from the control table 4' to a control voltage, Control section 6 for controlling the above sections
The oscillation frequency is kept constant by changing the control voltage of the VCXO1 according to the ambient temperature. As shown in FIG. 12, the data in the control table 4 ′ is obtained by changing the temperature-control voltage characteristics of each VCXO over the entire temperature range of −30 ° C. to + 70 ° C. And find a control voltage at which the VCXO frequency is constant at that temperature.
The control voltage for that temperature had to be written to the ROM and used as the control table 4 ', which required a great deal of time and effort. Therefore, there is a problem that a crystal oscillator with temperature compensation having good performance is not only expensive but also cannot be mass-produced.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a crystal oscillator with a temperature compensation which can easily obtain the temperature-control voltage characteristic of each VCXO and is suitable for mass production. It is an object.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an AT which controls an oscillation frequency by a control voltage.
Cut VCXO (Voltage Controlled Crystal Oscillat
or), a temperature sensor for detecting an ambient temperature, an A / D converter for converting a temperature signal from the temperature sensor into temperature data, and a circuit for oscillating the VCXO at a constant frequency with respect to the temperature data. A control table that stores the control voltage data as a table, a D / A converter that converts the control voltage data output from the control table into a control voltage,
A temperature-compensated crystal oscillator comprising a control section for controlling each section, wherein the control frequency of the VCXO is changed in accordance with the ambient temperature so as to keep the oscillation frequency constant. A four-point data input unit configured with a non-volatile memory capable of inputting control voltage data for at least four different temperature data to the control unit, a four-point data storage unit storing the same four-point data, A calculating unit for calculating a cubic curve based on the quaternary data, a cubic curve storing unit for storing the cubic curve, and control voltage data corresponding to predetermined temperature data based on the cubic curve And a control data writing unit for calculating and writing the control voltage data to the rewritable nonvolatile memory, and inputting the respective control voltage data for the previously measured four-point temperature data from the four-point data input unit. The Rukoto, and the temperature compensated crystal oscillator control voltage data to be written in the rewritable nonvolatile memory corresponding to a predetermined temperature data.

A frequency setting section for setting and storing the oscillation frequency of the VCXO in the control section; a frequency data input section for inputting frequency data of oscillation of the VCXO;
A frequency determination unit that determines by comparing the same frequency data with the set frequency, and based on the determination result, determines whether the VCXO
A VCXO voltage control unit for outputting the control voltage data of the above and a start button for instructing the start of the measurement.
Between the output of the XO and the frequency data input section,
A frequency measuring device that measures the frequency of the output signal of the XO and outputs frequency data is connected, the ambient temperature is set to a predetermined temperature, and the start button is pressed. Obtain control voltage data at which the oscillation frequency becomes the set frequency, store control voltage data corresponding to the temperature data in the four-point data storage unit,
This is repeated for at least four different ambient temperatures, and when the four-point data is stored in the four-point data storage unit, a cubic curve is calculated based on the four-point data.
Based on the cubic curve, a temperature-compensated crystal oscillator is configured to write control voltage data corresponding to predetermined temperature data to the rewritable nonvolatile memory.

A four-point temperature storage unit that sets and stores at least four different temperature data in the control unit and compares the temperature data from the A / D conversion unit with the stored four-point temperature. A temperature determining unit for determining, and a measurement starting unit for instructing a start of measurement based on a determination result of the temperature determining unit, wherein the ambient temperature is changed, and When the temperature data of the temperature coincides with the four-point temperature stored in the four-point temperature storage unit, the measurement starting unit instructs the start of the measurement, and the control voltage data at which the oscillation frequency of the VCXO becomes the set frequency at the same ambient temperature. Asked,
Control voltage data corresponding to the same temperature data is stored in the four-point data storage unit, and the control voltage data is stored in the four-point temperature storage unit as four-point data for four different ambient temperatures. When stored in the unit, a cubic curve is calculated based on the quaternary data, and control voltage data corresponding to predetermined temperature data is written to the rewritable nonvolatile memory based on the cubic curve. This is a crystal oscillator with temperature compensation.

[0007] At least one point of the four-point data is 25 points.
It is a crystal oscillator with temperature compensation that is data of ° C.

A personal computer is connected to the four-point data input section, and a four-point data stored in the personal computer is transferred to provide a crystal oscillator with temperature compensation.

[0009]

As described above, in the crystal oscillator with temperature compensation according to the present invention, the control table is constituted by a rewritable nonvolatile memory, and the control section controls each of at least four different temperature data. A four-point data input unit for inputting voltage data, and a four-point data input unit for storing the four-point data
A point data storage unit, an operation unit for calculating a cubic curve based on the quaternary data, a cubic curve storage unit for storing the cubic curve, and a predetermined temperature data based on the cubic curve. And a control data writing unit for calculating control voltage data corresponding to the above and writing the control voltage data to the rewritable nonvolatile memory, and inputting each control voltage data for the previously measured four-point temperature data from the four-point data input unit. As a result, the control voltage data corresponding to the predetermined temperature data is written in the rewritable nonvolatile memory, so that only four temperatures need to be measured, the measurement time can be greatly reduced, and the manufacturing cost can be greatly reduced. Can be reduced.

A frequency setting section for setting and storing the oscillation frequency of the VCXO in the control section, a frequency data input section for inputting the frequency data for oscillating the VCXO, and comparing the frequency data with the set frequency. And a start button for instructing the start of measurement, while providing a VCXO voltage control section for outputting control voltage data of the VCXO based on the judgment result. A frequency measuring device that measures the frequency of the output signal of the VCXO and outputs frequency data is connected between the input unit and the input unit. The ambient temperature is set to a predetermined temperature, and the start button is pressed. The control voltage data at which the oscillation frequency of the VCXO at the ambient temperature is equal to the set frequency is obtained, and the control voltage data corresponding to the temperature data is converted to the control voltage data. Stored in the data storage unit, when a different at least 4 points 4 points data performed repeatedly about ambient temperature which is stored in the four-point data storage unit,
A cubic curve is calculated based on the four-point data, and control voltage data corresponding to predetermined temperature data is written in the rewritable nonvolatile memory based on the cubic curve. Even if the data is not measured, the four-point data is automatically input simply by changing the measurement temperature and pressing the start button, so that the writing time of the control table can be greatly reduced.

[0011] The control unit may have at least four different predetermined settings.
A four-point temperature storage unit for setting and storing point temperature data;
A temperature determination unit that determines by comparing the temperature data from the A / D conversion unit with the stored four-point temperature; and a measurement activation unit that instructs a measurement start based on the determination result of the temperature determination unit. When the ambient temperature is changed, the temperature determination unit instructs the measurement start unit to start measurement when the temperature data from the A / D conversion unit matches the four-point temperature stored in the four-point temperature storage unit. And the VCXO at the same ambient temperature.
Control voltage data at which the oscillating frequency becomes the set frequency, control voltage data corresponding to the temperature data is stored in the four-point data storage unit, and the control voltage data is stored in the four-point temperature storage unit. When the ambient temperature of a point is stored as four-point data in the four-point data storage unit, a cubic curve is calculated based on the four-point data, and corresponding to predetermined temperature data based on the cubic curve. Since the control voltage data is written in the rewritable nonvolatile memory, for example, by changing the ambient temperature in a predetermined temperature range, the four-point data is automatically measured, and the control table is written. Write time reduction and
Labor costs can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a crystal oscillator with temperature compensation according to the present invention will be described in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of a crystal oscillator with temperature compensation according to the present invention. In the figure, reference numeral 1 denotes an AT-cut VCXO (Voltage Controlled Crysta) which controls an oscillation frequency by a control voltage.
l Oscillator), 2 is a temperature sensor that detects the ambient temperature,
Reference numeral 3 denotes an A / D converter for converting a temperature signal from the temperature sensor 2 into temperature data. Reference numeral 4 denotes a flash memory as a rewritable nonvolatile memory that stores, as a control table, control voltage data for causing the oscillation of the VCXO 1 to have a constant frequency with respect to the temperature data from the A / D converter 3. Reference numeral 5 denotes a D / A converter for converting control voltage data output from the flash memory 4 into a control voltage. Reference numeral 6 denotes a control unit which includes a CPU 6a, a ROM 6b, a RAM 6
c, etc., and controls each unit. Reference numeral 7 denotes a four-point data input unit for inputting control voltage data for at least four different temperature data. Reference numeral 8 denotes a four-point data storage unit that stores the four-point data input from the four-point data input unit 7. Reference numeral 9 denotes a calculation unit that calculates a cubic curve based on the four-point data stored in the four-point data storage unit 8. A cubic curve storage unit 10 temporarily stores the cubic curve calculated by the calculation unit 9. A control data writing unit 11 calculates control voltage data corresponding to predetermined temperature data based on the cubic curve stored in the cubic curve storage unit 10 and writes the control voltage data into the flash memory 4. Reference numeral 30 denotes a personal computer which is connected to the four-point data input unit 7 and stores control voltage data for four different temperature data measured in advance and outputs the same four-point data to the four-point data input unit 7. is there.

FIG. 2 is a block diagram showing another embodiment of the crystal oscillator with temperature compensation according to the present invention. In the figure, the same functions as those in FIG. 1 are indicated by the same symbols, and the description is omitted. 7 '
Is a frequency data input section for inputting the frequency data for oscillating the VCXO1. A frequency setting unit 12 sets and stores the oscillation frequency of the VCXO1. Reference numeral 13 denotes a frequency determination unit that determines by comparing frequency data from the frequency data input unit with a set frequency from the frequency setting unit 12. Reference numeral 14 denotes a VCXO voltage control unit that outputs control voltage data of the VCXO1 based on the determination result of the frequency determination unit 13. Reference numeral 15 denotes a start button for giving an instruction to measure a control voltage for setting the oscillation frequency of the VCXO 1 to a set frequency for a predetermined ambient temperature. 50 is connected between the output of the VCXO1 and the frequency data input unit 7 ',
1 is a frequency measuring device that measures the frequency of the output signal and outputs frequency data to a frequency data input unit 7 '.

FIG. 3 is a block diagram showing another embodiment of the crystal oscillator with temperature compensation according to the present invention. In the figure, the same functions as those in FIG. 1 and FIG. Reference numeral 16 denotes a four-point temperature storage unit that sets and stores predetermined four different temperature data. Reference numeral 17 denotes a temperature determination unit that compares the temperature data from the A / D conversion unit 3 with the four-point temperatures stored in the four-point temperature storage unit 16 to determine the temperature difference. Reference numeral 18 denotes a measurement activation unit which instructs the temperature determination unit 17 to start measurement when the temperature data from the A / D conversion unit 3 matches the four-point temperature stored in the four-point temperature storage unit 16.

The operation of the above configuration will now be described. First, the AT cut VCXO (Voltage Control
Controlled Crystal Oscillator) 1 will be described first.
The temperature (x (° C.))-Oscillation frequency characteristic (Z (Hz)) of the AT cut VCXO1 is represented by a cubic curve as shown in FIG.

(Equation 1) Also, the control voltage (Y (V)) of the AT cut VCXO1
The oscillation frequency characteristic (Z (Hz)) is expressed by a linear equation as shown in FIG.

(Equation 2) The control voltage sensitivity e (Hz / V) of this VCXO1 is constant over the entire temperature range. As can be seen from FIGS. 4 and 5, VC that keeps the oscillation frequency constant regardless of the temperature
The XO temperature compensation control means that Z = G (G: Cons in FIG. 4).
(tant). Further, as shown in FIG. 5, if Z−G <0, the control voltage must be increased so that Z = G. From the above, the following equation is derived using the slope (control voltage sensitivity) e of Equation 2.

(Equation 3) Rewriting using Equation 1

(Equation 4) From the condition that Z = G when Y = 2.5 V in the equation 2,

(Equation 5) Is obtained. Comparing Equation 5 with Equation 1 and confirming the sign of ZG, successively changing and substituting the value of x, it can be seen that Equation 5 can be written as follows.

(Equation 6) From the above, the temperature-control voltage characteristic for keeping the VCXO at a constant frequency can be represented by a cubic curve, as shown in FIG. Since Equation 6 has four unknowns A to D, if data of four different measurement points is obtained, the values of A to D can be determined. In the case of FIG. 6, the measurement point 3 (x: 25 ° C., y:
Since the value of (2.5 V) is known, any other three points may be measured.

As can be seen from the above description, four (x,
y) If the data is known, a cubic curve can be calculated. First, the (x, y) data of these four points is measured for each VCXO and input to the personal computer 30. FIG. 7 is an operation flow for explaining the operation in the configuration shown in FIG. 1, and will be described below with reference to FIG. The four-point data (x, y) is input from the personal computer 30 to the four-point data input unit 7 and stored in the four-point data storage unit (ST).
1). The four-point data (x,
Based on y), the calculation unit 9 performs the following calculation to calculate a cubic curve. The 4-point data _{(x = x 1, x 2} , x 3, x 4,
y = y _1, y _2, y _3, y ₄ ) is substituted into Equation 6 to form a matrix R having 4 rows and 4 columns (ST2).

(Equation 7) The inverse matrix of R is obtained and multiplied from the left to obtain the values of A to D (ST3).

(Equation 8) The "Gaussian elimination method" is used when obtaining the inverse matrix. Therefore, as shown in FIG. 8, an enlarged matrix area used in the Gaussian elimination method is reserved on the RAM 6c in advance.

The unknowns A to D are obtained as described above.
However, since the units of the unknowns A to D are (° C.), a control table cannot be created by using the determined equations 6 of the unknowns A to D. The temperature of the temperature sensor used (x
(° C.))-Output voltage (T (V)) characteristic is represented by the following linear expression.

(Equation 9) The equation 9 is substituted into the equation 6 in which the unknowns A to D are determined, and the coefficients Av to Dv of the new cubic equation are obtained (ST4).

(Equation 10) In Equation 10, T represents temperature, and its unit is (Volt).

Next, using Equation 10 in which all coefficients are determined,
The control data writing unit 11 creates a control table used for the VCXO temperature compensation control and writes the control table in the flash memory 4 (ST5). For example, an 8-bit ADC sets 0-5V to 2
In order to decompose into 56 gradations, one step is about 0.019V
Of 256 steps. Therefore, the control table may be created for 256 temperature points from 0 to 5 V as shown in FIG. In practice, first, T in equation 10:
Substituting 0.0196 (V) for calculation, the resulting value Y
Is divided by 0.0196. Thereafter, the value of T is changed to 0.0
The calculation is advanced while increasing by 196 (V), and when the 256 calculations are completed, the control table in FIG. 9 is obtained. As described above, the control table can be written in the flash memory 4.

Next, the case of the embodiment of FIG. 2 will be described. In the embodiment of FIG. 1, four-point data is measured in advance and stored in the personal computer 30, and the control table is created and stored by inputting the four-point data from the personal computer 30. In this case, by setting the ambient temperature to a predetermined temperature and pressing the start button 15, the frequency of the VCXO measured by the frequency
VCXO voltage control unit 1 so that the frequency is set to
4 is controlled, and the control voltage at that time is stored in a four-point data storage unit 8.
The four-point data can be written to the four-point data storage unit 8 by repeatedly performing this process for the four ambient temperatures. For this reason,
In the embodiment of FIG. 1, the four-point data of the VCXO which has been measured in advance and stored in the personal computer 30 can be written into the four-point data storage unit 8 simultaneously with the measurement, and as described in the embodiment of FIG. A control table can be created and written to the flash memory 4, which can significantly reduce the time.

Next, the embodiment of FIG. 3 will be described.
In the case of the embodiment shown in FIG. 2, the measurement is started by pressing the start button 15, and this must be repeated four times. In the embodiment of FIG. 3, the ambient temperature is automatically changed by changing the ambient temperature to pass the four temperatures.
The point data is measured and stored, a control table is created and written to the flash memory 4. The four-point temperature storage unit 16 stores the temperatures at four points to be measured. When the ambient temperature is changed, the temperature sensor 2 detects the ambient temperature, and when the temperature determining unit 17 determines that the detected temperature is the same as one point of the set temperature, the measurement starting unit starts the measurement, and The VCXO voltage controller 14 controls the frequency of the VCXO measured by the measuring device 50 to be the frequency set in the frequency setting unit 13, and the control voltage at that time is written in the four-point data storage unit 8. . By repeating this four times, four-point data is automatically collected without any human operation, written into the four-point data storage unit 8, and a control table is created as described in the embodiment of FIG. , Can be written to the flash memory 4. In addition, by setting one point of the ambient temperature of the four points to be measured to 25 ° C. which is known data in advance, the measurement is performed for three points.
The measurement can be completed in a single round, and the measurement time can be further reduced to 3/4.

As shown in FIG. 10, when the temperature sensor 2 detects an ambient temperature, for example, -28 ° C., the temperature data of 0.098 V is used as a temperature signal as a temperature signal in the control table written in the flash memory 4 as described above. 2 and the A / D converter 3 outputs temperature data 5. The temperature data 5 is input as an address to the flash memory 4 that stores a control table, and 200 is output as control voltage data. This control voltage data 200
Is converted to an analog voltage of 3.9200 V by the D / A converter 5, and is used to control the VCXO1.

[0022]

As described above, according to the crystal oscillator with temperature compensation according to the present invention, the control table is composed of a rewritable nonvolatile memory, and the control unit has a different configuration.
Input each control voltage data for the temperature data of the point 4
A point data input unit, a four-point data storage unit that stores the four-point data, a calculation unit that calculates a cubic curve based on the four-point data, and a cubic curve storage unit that stores the cubic curve When,
A control data writing unit that calculates control voltage data corresponding to predetermined temperature data based on the cubic curve and writes the control voltage data into the rewritable nonvolatile memory; By inputting each control voltage data from the four-point data input unit, the control voltage data corresponding to the predetermined temperature data is written in the rewritable nonvolatile memory, so that only four temperatures need to be measured. The measurement time can be greatly reduced, and the manufacturing cost can be significantly reduced.

Further, the control section has a frequency setting section for setting and storing the oscillation frequency of the VCXO, a frequency data input section for inputting the frequency data of the oscillation of the VCXO, and comparing the frequency data with the set frequency. And a start button for instructing the start of measurement, while providing a VCXO voltage control section for outputting control voltage data of the VCXO based on the judgment result. A frequency measuring device that measures the frequency of the output signal of the VCXO and outputs frequency data is connected between the input unit and the input unit. The ambient temperature is set to a predetermined temperature, and the start button is pressed. The control voltage data at which the oscillation frequency of the VCXO at the ambient temperature is equal to the set frequency is obtained, and the control voltage data corresponding to the temperature data is converted to the control voltage data. When the four-point data is stored in the four-point data storage part, and a cubic curve is calculated based on the four-point data, the cubic curve is calculated. Since the control voltage data corresponding to the predetermined temperature data is written in the rewritable nonvolatile memory based on the cubic curve,
Even if the four-point data is not measured in advance, the four-point data is automatically input simply by changing the measurement temperature and pressing the start button, so that the time for writing the control table can be greatly reduced.

A four-point temperature storage unit for setting and storing predetermined four different temperature data in the control unit;
A temperature determination unit that determines by comparing the temperature data from the conversion unit with the stored four-point temperature; and a measurement activation unit that instructs the start of measurement based on the determination result of the temperature determination unit. The temperature is changed, and the temperature determination unit
When the temperature data from the / D conversion unit matches the four-point temperature stored in the four-point temperature storage unit, the measurement start unit instructs the start of measurement, and the oscillation frequency of the VCXO at the same ambient temperature is set to the set frequency. And the control voltage data corresponding to the same temperature data is stored in the four-point data storage unit, and the control voltage data is stored in the four-point temperature storage unit for four different ambient temperatures. When stored in the 4-point data storage unit as data, a cubic curve is calculated based on the 4-point data, and based on the cubic curve,
Since the control voltage data corresponding to the predetermined temperature data is written in the rewritable nonvolatile memory, for example, by changing the ambient temperature to a predetermined temperature range,
The 4-point data is automatically measured and the control table is written, so that the writing time can be greatly reduced and the labor cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a crystal oscillator with temperature compensation according to the present invention.

FIG. 2 is a block diagram showing another embodiment of the crystal oscillator with temperature compensation according to the present invention.

FIG. 3 is a block diagram showing another embodiment of the crystal oscillator with temperature compensation according to the present invention.

FIG. 4 shows a VCX of a crystal oscillator with temperature compensation according to the present invention.
FIG. 4 is a characteristic diagram showing a temperature-oscillation frequency characteristic of O.

FIG. 5 shows a VCX of a crystal oscillator with temperature compensation according to the present invention.
FIG. 4 is a characteristic diagram showing a control voltage-oscillation frequency characteristic of O.

FIG. 6 shows a VCX of a crystal oscillator with temperature compensation according to the present invention.
FIG. 5 is a characteristic diagram showing a temperature-control voltage characteristic for keeping the oscillation frequency of O constant.

FIG. 7 is an operation flow for explaining the operation of the crystal oscillator with temperature compensation according to the present invention.

FIG. 8 is a diagram showing an enlarged matrix region used in the Gaussian elimination method in the crystal oscillator with temperature compensation according to the present invention;
This area is secured on the RAM.

FIG. 9 is a diagram showing an example of a control table of the crystal oscillator with temperature compensation according to the present invention.

FIG. 10 is a schematic block diagram for explaining the operation of the crystal oscillator with temperature compensation according to the present invention.

FIG. 11 is a block diagram showing a conventional crystal oscillator with temperature compensation.

FIG. 12 is a characteristic diagram showing a temperature-control voltage characteristic for keeping the oscillation frequency of VCXO of the crystal oscillator with temperature compensation constant.

[Explanation of symbols]

1 AT-cut VCXO (Voltage Controlled Crystal
Oscillator) 2 Temperature sensor 3 A / D converter 4 Flash memory 5 D / A converter 6 Controller 6a CPU 6b ROM 6c RAM 7 Four-point data input part 7 'Frequency data input part 8 Four-point data storage part 9 Operation part Reference Signs List 10 cubic curve storage unit 11 control data writing unit 12 frequency setting unit 13 frequency judgment unit 14 VCXO voltage control unit 15 start button 30 personal computer 50 frequency measuring device

Claims (5)

[Claims] 1. An oscillator for controlling an oscillation frequency by a control voltage.
T-cut VCXO (Voltage Controlled Crystal Oscill
ator), a temperature sensor for detecting an ambient temperature, an A / D converter for converting a temperature signal from the temperature sensor into temperature data, and a circuit for oscillating the VCXO at a constant frequency with respect to the temperature data. A control table that stores the control voltage data of the VCXO as a table, a D / A conversion unit that converts the control voltage data output from the control table into a control voltage, and a control unit that controls each unit.
A temperature-compensated crystal oscillator in which the oscillation frequency is kept constant by changing the control voltage of the control unit in accordance with the ambient temperature, wherein the control table is constituted by a rewritable nonvolatile memory, and the control unit A four-point data input unit for inputting each control voltage data for at least four different temperature data, a four-point data storage unit for storing the four-point data,
A calculating unit for calculating a cubic curve based on the quaternary data, a cubic curve storing unit for storing the cubic curve, and control voltage data corresponding to predetermined temperature data based on the cubic curve And a control data writing unit for calculating and writing the control voltage data to the rewritable nonvolatile memory, and inputting each control voltage data for the previously measured four-point temperature data from the four-point data input unit, A crystal oscillator with temperature compensation, wherein control voltage data corresponding to temperature data is written in the rewritable nonvolatile memory. 2. A frequency setting section for setting and storing an oscillation frequency of the VCXO in the control section, a frequency data input section for inputting frequency data for oscillating the VCXO, And a frequency determination unit that determines by comparing the VC
While providing a VCXO voltage control unit for outputting control voltage data of XO and a start button for instructing the start of measurement, between the output of VCXO and the frequency data input unit,
A frequency measuring device for measuring the frequency of the output signal of the VCXO and outputting frequency data is connected. By setting the ambient temperature to a predetermined temperature and pressing the start button, the VCXO at the ambient temperature is depressed. Obtain control voltage data at which the oscillation frequency of
When the control voltage data corresponding to the same temperature data is stored in the four-point data storage unit, and this is repeated for at least four different ambient temperatures, the four-point data is stored in the four-point data storage unit. A cubic curve is calculated based on the four-point data, and control voltage data corresponding to predetermined temperature data is written to the rewritable nonvolatile memory based on the cubic curve. The crystal oscillator with temperature compensation according to claim 1. 3. The control unit has at least four different predetermined settings.
A four-point temperature storage unit for setting and storing point temperature data;
A temperature determination unit that determines by comparing the temperature data from the A / D conversion unit with the stored four-point temperature; and a measurement activation unit that instructs a measurement start based on the determination result of the temperature determination unit. The ambient temperature is changed, and the temperature determination unit determines the A / D
When the temperature data from the conversion unit matches the four-point temperature stored in the four-point temperature storage unit, the measurement start unit instructs the start of measurement, and the control is performed such that the oscillation frequency of the VCXO at the same ambient temperature becomes the set frequency. Voltage data is obtained, control voltage data corresponding to the temperature data is stored in the four-point data storage unit, and the control voltage data is stored as four-point data for four different ambient temperatures stored in the four-point temperature storage unit. When stored in the four-point data storage unit, a cubic curve is calculated based on the four-point data, and control voltage data corresponding to predetermined temperature data is calculated based on the tertiary curve. 2. The crystal oscillator with temperature compensation according to claim 1, wherein said crystal oscillator is written in a volatile memory. 4. At least one point of the four-point data is 2
4. The crystal oscillator with temperature compensation according to claim 1, wherein the data is 5 ° C. data. 5. The crystal oscillator with temperature compensation according to claim 1, wherein a personal computer is connected to said four-point data input unit.