JP5420235B2 - Temperature compensation value setting method for temperature compensated crystal oscillator - Google Patents

Description

  The present invention relates to a temperature compensated crystal oscillator (TCXO: Temperature Compensated Crystal Oscillator) setting method, and in particular, a temperature compensated type capable of easily setting a temperature compensated value of a D / A converter used therein. The present invention relates to a method for setting a temperature compensation value of a crystal oscillator.

[Temperature compensation value setting method for conventional temperature compensated crystal oscillator: Fig. 2]
A temperature compensation value setting method for a conventional temperature compensated crystal oscillator will be described with reference to FIG. FIG. 2 is a schematic diagram showing a system according to a temperature compensation value setting method of a conventional temperature compensated crystal oscillator.
A system (conventional system) according to a temperature compensation value setting method of a conventional temperature compensated crystal oscillator includes a temperature sensor (TEMP. SENSOR) 1 and an A / D converter (A / D) 2 as shown in FIG. A CPU (Central Processing Unit) 3, a D / A converter (D / A) 4, a VCXO (Voltage Controlled Crystal Oscillator) 5, an output terminal 6, and a frequency A counter 7 and a personal computer (PC) 8 are provided.
Here, the temperature sensor 1, the A / D converter 2, the CPU 3, the D / A converter 4, and the VCXO 5 constitute a TCXO.

[Parts of the conventional system]
Each part in the conventional system of FIG. 2 will be described.
The temperature sensor (TEMP. SENSOR) 1 detects the temperature of the outer periphery of the crystal oscillator and outputs an analog value to the A / D converter 2 as a detected temperature value.
The A / D converter (A / D) 2 converts the analog detected temperature value from the temperature sensor 1 into a digital value and outputs it to the CPU 3 and the PC 8.

A CPU (Central Processing Unit) 3 includes a control unit and an EEPROM of an internal memory, operates by program processing, and corresponds to a detected temperature value input from the A / D converter 2 and set in the internal memory. The control voltage value is output to the D / A converter 4.
Further, the CPU 3 performs a process of storing a control voltage value corresponding to the temperature value input from the PC 8 in the internal memory.
The control voltage value becomes the temperature compensation value of the D / A converter 4.

The D / A converter (D / A) 4 converts the voltage value for controlling the VCXO 5 output from the CPU 3 from digital to analog, and outputs a control voltage to the control terminal of the VCXO 5.
The VCXO 5 receives a control voltage corresponding to the detected temperature input from the D / A converter 4, varies the oscillation frequency according to the control voltage, and outputs an oscillation frequency signal to the output terminal 6.

The output terminal 6 outputs an oscillation frequency signal to the outside and outputs the oscillation frequency signal to the frequency counter 7.
The frequency counter 7 counts the frequency of the oscillation frequency signal input from the output terminal 6 and outputs the count value to the PC 8.

The personal computer (PC) 8 stores in advance a control voltage value for controlling the VCXO 5 corresponding to the standard temperature value, and further counts output from the frequency counter 7 at the standard temperature (standard temperature). The value is stored in association with the standard temperature value.
Then, the PC 8 sets the control voltage value at the standard temperature in the internal memory of the CPU 3.

  When the outer peripheral temperature changes and the count value from the frequency counter 7 changes, the PC 8 adjusts the control voltage value supplied to the VCXO 5 so that the count value becomes equal to the count value at the standard temperature. The temperature value and the control voltage value are stored in association with each other, and are also set in the internal memory of the CPU 3.

  In this way, control voltage values corresponding to various temperature values are set in the internal memory of the CPU 3, and the CPU 3 refers to the internal memory and converts the control voltage value corresponding to the temperature change to the D / A converter. 4, and further output from the D / A converter 4 to the VCXO 5, so that the oscillation frequency can be varied according to the temperature change in the VCXO 5.

[Operation of conventional system]
The temperature sensor 1 detects the temperature of the outer periphery, and outputs the detected temperature value to the A / D converter 2.
The A / D converter 2 converts the detected temperature from analog to digital and outputs it to the CPU 3.
In the CPU 3, the control voltage value of the VCXO 5 corresponding to the detected temperature set in the internal memory is read and output to the D / A converter 4. Here, when the detected temperature is the reference temperature, a digital value of the reference control voltage that is not subjected to temperature compensation control is output.
The D / A converter 4 converts the control voltage value from digital to analog and outputs it as a control voltage of the VCXO 5. The VCXO 5 outputs a frequency signal corresponding to the control voltage.

Here, the compensation value is determined by the frequency counter 7 and the PC 8 so that the frequency at a certain temperature has no frequency difference from the reference temperature.
When the outer periphery is at the reference temperature, for example, a desired frequency obtained at the output terminal 6 of the VCXO 5 at 25 ° C. is counted by the frequency counter 7 and output to the PC 8.
In the PC 8, the output value (reference detected temperature value) from the A / D converter 2 and the count value from the frequency counter 7 are input and stored in association with each other, and the reference detected temperature value and the temperature in advance are stored. The reference control voltage value stored in association with the value is output to the CPU 3, and the reference temperature value and the reference control voltage value are stored (set) in association with each other in the internal memory (EEPROM) of the CPU 3.

  Next, when the temperature of the outer periphery is set to, for example, −40 ° C., the output frequency of the output terminal 6 changes depending on the temperature characteristic of the VCXO 5. As described above, the PC 8 controls the CPU 3 to change the output value of the D / A converter 4 and controls until the value of the frequency counter 7 matches the count value at 25 ° C.

When the count values match, the detected temperature value at the A / D converter 2 at that time and the control voltage value for the VCXO 5 are associated (stored) in the internal memory of the CPU 3.
Such a series of operations is performed for each temperature step, for example, up to + 85 ° C., but the repetitive operation is performed between the program in the CPU 3 and the program in the PC 8.

As a related prior art, there is “Oscillator” (Applicant: Maspro Electric Co., Ltd.), Japanese Patent Laid-Open No. 2000-036739 (Patent Document 1).
In Patent Document 1, in an oscillation device, a control voltage is obtained based on a temperature detection value and control data stored in a storage element, and this is input to an oscillation circuit to control an oscillation frequency and generated by a GPS receiver. In the case where the oscillation frequency can be controlled by the PLL device using the reference signal generated, the control data in the storage element is updated based on the control voltage output from the PLL device and the detected temperature value.

Japanese Patent Laid-Open No. 2001-036342 “Quartz Oscillator with Temperature Compensation” (Applicant: Fujitsu General Limited) (Patent Document 2).
In Patent Document 2, in a crystal oscillator with temperature compensation, a cubic curve is calculated based on at least four temperature data and control voltage data, and control voltage data corresponding to predetermined temperature data is calculated based on the cubic curve. Is calculated and written to the flash memory, and the temperature-control voltage characteristic of the VCXO is simply obtained.

Further, Japanese Patent Laid-Open No. 2002-077674 “Method for Adjusting Temperature Compensated Oscillator” (Applicant: Citizen Co., Ltd.) is available (Patent Document 3).
In Patent Document 3, in a method of adjusting a temperature compensated oscillator, the temperature compensated oscillator is housed in a temperature vessel, the temperature signal of the temperature vessel is changed, the output signal from the temperature compensated oscillator is measured, and the compensation is based only on the measurement signal. It has been shown to create data and store it in a temperature compensated oscillator.

JP 2000-036739 A JP 2001-036342 A JP 2002-077674 A

  However, in the temperature compensation value setting method of the conventional temperature compensated crystal oscillator described with reference to FIG. 2, in order to determine the temperature compensation value to the D / A converter for various detection temperatures, Since the operation is repeated until the count value of the frequency counter matches the standard count value, it takes a long time to obtain the temperature compensation value.

  Moreover, in patent documents 1-3, it is about acquiring easily the temperature compensation value to a D / A converter, and confirming whether the acquired temperature compensation value is appropriate, and if it is inadequate, performing fine adjustment. It is not disclosed until.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a temperature compensation value setting method for a temperature-compensated crystal oscillator capable of acquiring the temperature compensation value of the D / A converter at each temperature in a short time. To do.

  Further, the present invention provides a temperature compensation value setting method for a temperature compensated crystal oscillator that can confirm whether or not the acquired temperature compensation value is appropriate, and can finely adjust the temperature compensation value when it is not appropriate. The purpose is to provide.

The present invention for solving the problems of the above conventional example includes a voltage-controlled crystal oscillator that varies the oscillation frequency in accordance with an input control voltage, a temperature sensor that detects the temperature of the outer periphery, and the detected temperature A / D converter for analog / digital conversion of value, and central processing unit for outputting a value of control voltage supplied to voltage controlled crystal oscillator as temperature compensation value for detected temperature value from A / D converter And a temperature compensation value setting method in a temperature compensated crystal oscillator having a D / A converter for digital / analog conversion of the temperature compensation value, the oscillation frequency signal from the voltage controlled crystal oscillator and the highly stable reference frequency signal The phase is compared, the control voltage is output so that there is no phase shift with respect to the reference frequency signal, and the lock signal is output with the state without the phase shift set to the locked state. A switch that selects either the output from the D / A converter or the control voltage output from the PLL circuit and inputs it to the voltage controlled crystal oscillator, and the detected temperature from the A / D converter is input to the PLL circuit. A personal computer that inputs a lock signal from the control circuit, inputs a control voltage output from the PLL circuit as a voltage value, controls a switch, and outputs a temperature value and a control voltage value corresponding to the temperature value to the central processing unit And a frequency counter that counts the frequency of the oscillation frequency signal from the voltage-controlled crystal oscillator , and the personal computer selects the control voltage output from the PLL circuit until the lock signal is input from the PLL circuit. When the switch is controlled to input to the controlled crystal oscillator and the lock signal is input from the PLL circuit, the detected temperature from the A / D converter Stores the count value of the voltage value and the frequency counter of the control voltage output from the values and the PLL circuit, obtains a temperature compensation value set to the central processing unit as the value of the value of the detected temperature and the control voltage in the lock state to the, D / selects the output from the a converter controls the switch to input to the voltage controlled crystal oscillator, the count value obtained by the frequency counter for oscillation frequency signal from the voltage controlled crystal oscillator and the a / D Compared with the count value stored corresponding to the value of the detected temperature from the converter, the confirmation operation to determine the appropriateness of the value of the control voltage set in the central processing unit is performed and set in the central processing unit If it is determined that the control voltage value is inappropriate, the control voltage value is adjusted, and the count value obtained by the frequency counter is stored in correspondence with the detected temperature value from the A / D converter. A fine adjustment operation is performed so as to be equal to the current value, and the finely adjusted detected temperature value and control voltage value are reset in the central processing unit .

  The present invention is characterized in that, in the temperature compensation value setting method, the personal computer acquires a temperature compensation value for each temperature, performs a confirmation operation, and repeats the fine adjustment operation.

According to the present invention, the voltage controlled crystal oscillator varies the oscillation frequency according to the input control voltage, the temperature sensor detects the temperature of the outer periphery, and the A / D converter detects the detected temperature value. Analog / digital conversion, and the central processing unit outputs the control voltage value supplied to the voltage controlled crystal oscillator as the temperature compensation value for the detected temperature value from the A / D converter, and D / A conversion The device converts the temperature compensation value from digital to analog, and the PLL circuit inputs the oscillation frequency signal from the voltage-controlled crystal oscillator and the highly stable reference frequency signal, compares the phase, and shifts the phase relative to the reference frequency signal. The control voltage is output so that there is no phase shift, and the lock signal is output with the state without phase shift as the lock state, and the switch selects either the output from the D / A converter or the control voltage output from the PLL circuit. The Input to pressure controlled crystal oscillator, personal computer inputs detected temperature from A / D converter, lock signal from PLL circuit, control voltage output from PLL circuit as voltage value, switch , And output a temperature value and a control voltage value corresponding to the temperature value to the central processing unit , the frequency counter counts the frequency of the oscillation frequency signal from the voltage controlled crystal oscillator , Until the lock signal is input from the PLL circuit, the personal computer controls the switch so that the control voltage output from the PLL circuit is selected and input to the voltage controlled crystal oscillator, and when the lock signal is input from the PLL circuit, A to store the count value of the voltage value and the frequency counter of the control voltage output from the values and the PLL circuit of the detected temperature from the / D converter Together, when set to the central processing unit as the value of the value and the control voltage of the detected temperature of the locked state to acquire temperature compensation value, and inputs to the voltage controlled crystal oscillator to select the output from the D / A converter The switch is controlled, and the count value obtained by the frequency counter for the oscillation frequency signal from the voltage controlled crystal oscillator is compared with the count value stored corresponding to the detected temperature value from the A / D converter, When the confirmation operation for determining the appropriateness of the control voltage value set in the central processing unit is performed, and the control voltage value set in the central processing unit is determined to be inappropriate, the control voltage value is adjusted and the frequency Fine adjustment operation is performed so that the count value obtained by the counter becomes equal to the count value stored corresponding to the detected temperature value from the A / D converter, and the finely adjusted detected temperature value and control voltage value The Since the temperature compensation value setting method for the temperature compensated crystal oscillator to be reset in the central processing unit is used , the temperature compensation value can be obtained in a short time, the appropriateness of the temperature compensation value can be confirmed, and the temperature compensation value is if the proper is easily Ru effect that can be fine-tuned.

  According to the present invention, the personal computer acquires the temperature compensation value for each temperature, performs the confirmation operation, and repeats the fine adjustment operation. Therefore, the temperature compensation value is set for each temperature in a short time. There is an effect that can be obtained.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
A temperature-compensated crystal oscillator temperature compensation value setting method according to an embodiment of the present invention includes a voltage-controlled crystal oscillator, a temperature sensor, and A / D conversion for analog / digital conversion of a temperature value detected by the temperature sensor. , A central processing unit for outputting a control voltage value supplied to the voltage controlled crystal oscillator as a temperature compensation value with respect to a detected temperature value from the A / D converter, and digital / analog conversion of the temperature compensation value In a temperature-compensated crystal oscillator having a D / A converter, an oscillation frequency signal from a voltage-controlled crystal oscillator and a highly stable reference frequency signal are input to compare phases, and there is no phase shift with respect to the reference frequency signal A PLL circuit that outputs a control signal and outputs a lock signal in a locked state with no phase shift, and either an output from the D / A converter or an output from the PLL circuit A switch that inputs the voltage to the voltage controlled crystal oscillator and the detected temperature from the A / D converter, the lock signal from the PLL circuit, the output from the PLL circuit as the voltage value, A personal computer that controls the switch and outputs a temperature value and a control voltage value corresponding to the temperature value to the central processing unit. Until the personal computer receives a lock signal from the PLL circuit, the PLL circuit When the switch is controlled to input to the voltage controlled crystal oscillator and the lock signal is input from the PLL circuit, the detected temperature value from the A / D converter and the output voltage value from the PLL circuit are selected. The temperature compensation value is acquired by setting the value of the detected temperature in the locked state and the value of the control voltage in the central processing unit as well as storing the temperature compensation value. It can be obtained in time.

  Furthermore, the temperature compensation value setting method of the temperature compensated crystal oscillator according to the embodiment of the present invention is such that when the personal computer sets the value of the detected temperature in the locked state and the value of the control voltage in the central processing unit, D / The switch is controlled so that the output from the A converter is selected and input to the voltage controlled crystal oscillator, and the count value obtained by the frequency counter for the oscillation frequency signal from the voltage controlled crystal oscillator and the detection from the A / D converter The count value stored in correspondence with the temperature value is compared, a check operation is performed to determine the appropriateness of the control voltage value set in the central processing unit, and the control voltage value set in the central processing unit is If it is determined to be inappropriate, the value of the control voltage is adjusted, and the count value obtained by the frequency counter becomes the count value stored corresponding to the value of the detected temperature from the A / D converter. The finely adjusted detection temperature value and the control voltage value are reset in the central processing unit, and the correctness of the temperature compensation value can be confirmed and the temperature compensation value is incorrect. If so, fine adjustment can be easily performed.

[Method for Setting Temperature Compensation Value of Temperature Compensated Crystal Oscillator of the Present Invention: FIG. 1]
A temperature compensation value setting method for a temperature compensated crystal oscillator according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram of a system according to a temperature compensation value setting method for a temperature compensated crystal oscillator according to an embodiment of the present invention.
As shown in FIG. 1, a system (this system) according to a temperature compensation value setting method for a temperature compensated crystal oscillator according to an embodiment of the present invention includes a temperature sensor (TEMP. SENSOR) 11 and an A / D converter. (A / D) 12, CPU 13, D / A converter (D / A) 14, switch (SW) 15, VCXO 16, output terminal 17, buffer 18, and A / D converter (A / D) 19, a reference frequency input terminal 20, a PLL circuit (PLL) 21, a frequency counter 22, and a personal computer (PC) 23 are basically provided.

[Parts: Fig. 2]
Each part of this system will be specifically described.
The temperature sensor (TEMP. SENSOR) 11 detects the temperature of the outer periphery of the crystal oscillator and outputs an analog value to the A / D converter 12 as a detected temperature value.
The A / D converter (A / D) 12 converts the analog detected temperature value from the temperature sensor 11 into a digital value and outputs it to the CPU 13 and the PC 23.

The CPU 13 includes a control unit and an EEPROM of an internal memory, operates by a program process, and corresponds to a control voltage value (temperature compensation) set in the internal memory with respect to the detected temperature value input from the A / D converter 12. Value) is output to the D / A converter 14.
Further, the CPU 13 performs a process of storing a control voltage value (temperature compensation value) corresponding to the temperature value input from the PC 23 in the internal memory.

The D / A converter (D / A) 14 converts the voltage value for controlling the VCXO 16 output from the CPU 13 from digital to analog, and outputs a control voltage to the control terminal of the VCXO 16.
The switch (SW) 15 is controlled to be switched by the PC 23, and in the case of the temperature compensation value acquisition operation, the input side of the buffer 18 (the output side of the PLL 21) and the input side of the VCXO 16 are connected to each other to obtain the temperature compensation value. In the confirmation operation, the output side of the D / A converter 14 and the input side of the VCXO 16 are connected.

The VCXO 16 performs an oscillation operation according to the control voltage input from the D / A converter 14 via the SW 15 or the control voltage input from the PLL 21 via the SW 15, and outputs an oscillation frequency signal to the output terminal 17.
The output terminal 17 outputs an oscillation frequency signal to the outside and outputs the oscillation frequency signal to the PLL 21 and the frequency counter 22.

The buffer 18 amplifies the output signal from the PLL 21 and outputs it to the A / D converter 19.
The A / D converter (A / D) 19 converts the amplified signal from the buffer 18 from an analog signal to a digital signal, and outputs it to the PC 23.
The reference frequency input terminal 20 inputs a highly stable reference frequency generated by a cesium oscillator or the like, and outputs it to one input terminal of the PLL 21.

The PLL circuit (PLL) 21 inputs the reference frequency from the reference frequency input terminal 20 to one input terminal, inputs the oscillation frequency signal of the VCXO 16 from the output terminal 17 to the other input terminal, and sets the phase of both signals. In comparison, a control voltage for controlling the VCXO 16 is output based on the phase difference so that the oscillation frequency signal does not have a phase shift with respect to the reference frequency.
Then, the PLL 21 outputs a lock signal to the PC 23 when the two signals are in a locked state with no phase shift.

The frequency counter 22 counts the frequency of the frequency signal input from the output terminal 17 and outputs the count value to the PC 23.
The personal computer (PC) 23 inputs the temperature value detected by the temperature sensor 1 from the A / D converter 12 as a digital value as an operation for acquiring the temperature compensation value of the D / A converter 14, and buffers the SW15. A control signal is output to SW15 so as to connect the input side of 18 (the output side of PLL 21) and the input side of VCXO16.

When the PC 23 receives the lock signal from the PLL 21 after the SW 15 connects the input side of the buffer 18 and the input side of the VCXO 16, the voltage value (control voltage value) of the output of the PLL 21 that is input from the A / D converter 19. Is stored in the internal memory in association with the detected temperature value, and the count value from the frequency counter 22 is also stored in association with it.
Then, the PC 23 sets the detected temperature value and the control voltage value (temperature compensation value) in the internal memory of the CPU 13.

Further, the PC 23 outputs a control signal to the SW 15 so as to connect the output side of the D / A converter 14 and the input side of the VCXO 16 as a temperature compensation value confirmation operation.
After the SW 15 connects the output side of the D / A converter 14 and the input side of the VCXO 16, the CPU 13 sets the control voltage value (temperature compensation value) corresponding to the detected temperature value stored in the internal memory to the D / A. When output to the converter 14, the D / A converter 14 converts the control voltage value into an analog signal and outputs it to the VCXO 16 via the SW 15, and the VCXO 16 performs an oscillation operation.

The PC 23 inputs a value obtained by counting the oscillation frequency signal output from the VCXO 16 by the frequency counter 22, and corresponds to the input count value and the detected temperature value input from the A / D converter 12. The frequency is compared with the count value stored in the internal memory.
If the count value stored in the internal memory of the PC 23 matches the count value input from the frequency counter 22, it is determined that the set temperature compensation value is appropriate, and it is not necessary to finely adjust the temperature compensation value.

If the count value stored in the memory inside the PC 23 and the count value input from the frequency counter 22 do not match, the set temperature compensation value is regarded as inappropriate, and the temperature compensation value is finely adjusted.
In the fine adjustment method, the PC 23 adjusts the control voltage value corresponding to the detected temperature value stored in the internal memory, and inputs the frequency count value stored corresponding to the detected temperature value from the frequency counter 22. Make the count values match.
Then, the PC 23 overwrites and stores the finely adjusted control voltage value when the count values match in association with the detected temperature value, and sets the detected temperature value and the control voltage value in the internal memory of the CPU 13. .

Here, if the confirmation operation and the fine adjustment operation are not performed, the frequency counter 22 is not necessary.
Further, if the lock signal is not output from the PLL 21 to the PC 23 in the temperature compensation value acquisition operation, the frequency counter 22 is necessary, and the frequency count value for the standard temperature value is stored in the internal memory of the PC 23. When the count value input from the frequency counter 22 reaches the count value stored in the internal memory, the lock state is determined, and the detected temperature value and control voltage value at that time are also set in the internal memory of the CPU 13.

[Operation]
Next, the operation of this system will be described.
The PC 23 controls the SW 15 to connect the input side of the buffer 18 (the output side of the PLL 21) and the input side of the VCXO 16 in order to obtain a compensation value in the D / A converter 14, and inputs a highly stable reference signal. The output from the PLL 21 is output to the buffer 18 and the VCXO 16.

  The VCXO 16 performs an oscillation operation using the signal input from the PLL 21 as a control voltage, and outputs an oscillation frequency signal to the output terminal 17. The oscillation frequency signal output to the output terminal 17 is input to the other input terminal of the PLL 21 and is branched and output to the frequency counter 22.

  The PLL 21 compares the phase of the highly stable reference signal input from the reference frequency input terminal 20 with the oscillation frequency signal output from the VCXO 16, and enters a locked state in which there is no phase shift of the oscillation frequency signal with respect to the reference signal. The lock signal is output to the PC 23.

The PC 23 that has received the lock signal input from the PLL 21 is the temperature value input from the A / D converter 12 at that time and the PLL 21 that has been amplified by the buffer 18 and converted to a digital value by the A / D converter 19. The output voltage value (control voltage value) is acquired and stored in association with the internal storage unit. Here, the acquired control voltage value becomes a temperature compensation value for the D / A converter 14.
The PC 23 sets the acquired temperature value and the corresponding control voltage value in the internal memory of the CPU 13.

  The frequency counter 22 counts the frequency of the oscillation frequency signal from the VCXO 16 and outputs the count value to the PC 23. Accordingly, the PC 23 stores the count value of the oscillation frequency signal when the PLL 21 is locked in association with the temperature value.

  Next, the PC 23 controls the SW 15 to connect the output side of the D / A converter 14 and the input side of the VCXO 16 in order to confirm whether or not the temperature compensation value set in the CPU 13 is appropriate.

The CPU 13 outputs the temperature compensation value (control voltage value) set from the PC 23 to the D / A converter 14, is converted into an analog signal by the D / A converter 14, and is output to the VCXO 16.
Then, the VCXO 16 performs an oscillation operation with the control voltage input from the D / A converter 14 and outputs an oscillation frequency signal to the output terminal 17. Further, the oscillation frequency signal is input from the output terminal 17 to the frequency counter 22, the frequency of the signal is counted, and the count value is output to the PC 23.

When the count value input from the frequency counter 22 is equal to the count value stored when the PLL 21 is locked, the PC 23 determines that the set temperature compensation value is appropriate.
In addition, when the count value input from the frequency counter 22 is not equal to the count value stored when the PLL 21 is locked, the PC 23 determines that the set temperature compensation value is inappropriate and sets the temperature compensation value to be equal. Is finely adjusted, and the temperature compensation value when they become equal is reset in the internal memory of the CPU 13. Frequency shifts may occur due to variations in the connection system, which causes unequal cases.

  Thus, for each temperature, the PC 23 acquires the temperature compensation value (acquisition operation) while switching the SW 15, sets it in the internal memory of the CPU 13, and confirms whether the set temperature compensation value is appropriate as a confirmation operation. If there is a deviation in the set temperature compensation value, fine adjustment is performed to reset the temperature compensation value, and the temperature compensation value can be obtained for each temperature in a short time. It is.

  Further, the temperature compensation value is not obtained for each temperature step, and the temperature value of the A / D converter 12 and the temperature compensation value of the A / D converter 19 (output from the A / D converter 19 in the entire temperature range). Voltage value) may be stored in the internal memory of the PC 23 in association with each other, and the PC 23 may store the detected temperature value and the voltage value at that time in the internal memory of the CPU 3 for each temperature step.

  In the above method, the temperature of the VCXO 16 becomes known at the time of temperature compensation in an analog temperature compensation network (not shown), and the temperature in the analog temperature compensation network is made to match the curve of the compensation value. There is an advantage that a characteristic curve can be set.

[Effect of the embodiment]
According to the temperature compensation setting method of the temperature compensated crystal oscillator according to the present embodiment, as the temperature compensation value acquisition operation, the SW15 is switched so that the output of the PLL 21 is input to the VCXO 16, and the output is highly stable. When the reference frequency is input to the PLL 21 and becomes locked, the PC 23 stores the detected temperature value and the control voltage value to the PLL 21 at that time, and sets the detected temperature value and control voltage value in the internal memory of the CPU 13. Since the temperature compensation for the D / A converter 14 is performed, the temperature compensation value can be obtained in a short time.

  Further, according to the temperature compensation setting method of the temperature compensated crystal oscillator according to the present embodiment, as the temperature compensation value confirmation operation, the PC 23 switches the SW 15 and the output of the D / A converter 14 is input to the VCXO 16. The output of the VCXO 16 is counted by the frequency counter 22 and compared with the count value of the oscillation frequency of the VCXO 16 counted in the temperature compensation value acquisition operation. If they match, the temperature compensation value can be confirmed to be appropriate. There is.

  Further, according to the temperature compensation setting method of the temperature compensated crystal oscillator according to the present embodiment, as a fine adjustment operation of the temperature compensation value, if the count values do not match, the PC 23 counts by the temperature compensation value acquisition operation. D / A conversion is performed by adjusting the control voltage value to the VCXO 16 so as to obtain the counted value, and setting the detected temperature value and the control voltage value in the internal memory of the CPU 13 when the count value is reached. There is an effect that the temperature compensation value to the container 14 can be easily finely adjusted.

  The present invention is suitable for a temperature compensation value setting method for a temperature compensated crystal oscillator capable of acquiring a temperature compensation value of a D / A converter for each temperature in a short time.

It is the schematic of the system which concerns on the temperature compensation value setting method of the temperature compensation type | mold crystal oscillator which concerns on embodiment of this invention. It is the schematic which shows the system which concerns on the temperature compensation value setting method of the conventional temperature compensation type | mold crystal oscillator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Temperature sensor, 2 ... A / D converter (A / D), 3 ... CPU, 4 ... D / A converter (D / A), 5 ... VCXO, 6 ... Output terminal, 7 ... Frequency counter, 8 DESCRIPTION OF SYMBOLS ... Personal computer (PC), 11 ... Temperature sensor, 12 ... A / D converter (A / D), 13 ... CPU, 14 ... D / A converter (D / A), 15 ... Switch (SW), 16 ... VCXO, 17 ... output terminal, 18 ... buffer, 19 ... A / D converter (A / D), 20 ... reference frequency input terminal, 21 ... PLL circuit (PLL), 22 ... frequency counter, 23 ... personal computer ( PC)

Claims (2)

A voltage-controlled crystal oscillator that varies an oscillation frequency according to an input control voltage, a temperature sensor that detects the temperature of the outer periphery, an A / D converter that converts the detected temperature value from analog to digital, and A central processing unit that outputs, as a temperature compensation value, a value of a control voltage supplied to the voltage controlled crystal oscillator with respect to a detected temperature value from an A / D converter, and D for digital / analog conversion of the temperature compensation value A temperature compensation value setting method in a temperature compensated crystal oscillator having a / A converter,
The oscillation frequency signal from the voltage controlled crystal oscillator and a highly stable reference frequency signal are input and the phases are compared, and a control voltage is output so that there is no phase shift with respect to the reference frequency signal, and there is no phase shift A PLL circuit that outputs a lock signal in a locked state, a switch that selects either the output from the D / A converter or the control voltage output from the PLL circuit and inputs the control voltage to the voltage controlled crystal oscillator, The detected temperature from the A / D converter is input, the lock signal from the PLL circuit is input, the control voltage output from the PLL circuit is input as a voltage value, the switch is controlled, and the central processing unit a personal computer for outputting a value of the control voltage corresponding to the temperature value and the temperature value, the frequency for the oscillation frequency signal from the voltage controlled crystal oscillator Using a frequency counter that counts,
Until the lock signal is input from the PLL circuit, the personal computer controls the switch so that the control voltage output from the PLL circuit is selected and input to the voltage controlled crystal oscillator, and the personal computer locks from the PLL circuit. When a signal is input, the detected temperature value from the A / D converter, the voltage value of the control voltage output from the PLL circuit , and the count value in the frequency counter are stored, and the central processing unit is locked. When the temperature compensation value is obtained by setting the detected temperature value and the control voltage value, the switch is controlled so that the output from the D / A converter is selected and input to the voltage controlled crystal oscillator, For the oscillation frequency signal from the voltage controlled crystal oscillator, the count value obtained by the frequency counter and the detected temperature value from the A / D converter The control value stored in the central processing unit is compared, and the control voltage set in the central processing unit is checked to determine the appropriateness. The control voltage set in the central processing unit is incorrect. If the control voltage value is determined, the control voltage value is adjusted, and the count value obtained by the frequency counter is adjusted to be equal to the count value stored corresponding to the detected temperature value from the A / D converter. A temperature compensation value setting method characterized by performing an adjustment operation and resetting the finely-adjusted detected temperature value and control voltage value in the central processing unit . Personal computer obtains the temperature compensation value for each temperature, it performs a confirmation operation, the temperature compensation value setting method according to claim 1, wherein the repeating fine adjustment operation.

Images