JP2007067676A - Temperature compensation method,correction value determining circuit and temperature compensated oscillation circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature compensation method, a correction value determining circuit, and a temperature compensated oscillation circuit for executing temperature compensation by using a storage section with a small memory capacity. <P>SOLUTION: The correction value determining circuit 20 is configured to include: a temperature measurement section 22 for intermittently measuring the temperature of a piezoelectric resonator 40 and outputting the result of the measurement in the form of a digital signal; a counter 28 that receives higher-order bits in the digital signal except for the least significant bit, uses all the bits in the digital signal except for the least significant bit as the high order bits, and outputs the higher-order bits as an address value; and a storage section 30 that reads and outputs a correction value stored in advance in one-to-one cross-reference with each address value and in accordance with the address value received from the counter 28. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a temperature compensation method, a correction value determination circuit, and a temperature compensation oscillation circuit, and more particularly, to a temperature compensation method, a correction value determination circuit, and a temperature compensation oscillation circuit that perform temperature compensation in a digital manner.

  The temperature compensated oscillation circuit can constitute a temperature compensated piezoelectric oscillator or a real time clock module. FIG. 6 is a block diagram for explaining the configuration of a temperature compensated piezoelectric oscillator according to the prior art. The conventional digital temperature compensation type piezoelectric oscillator 1 stores correction value data for compensating the frequency temperature characteristic of the piezoelectric oscillator 1 in the storage unit 2 in advance. Further, the piezoelectric oscillator 1 measures the ambient temperature of the piezoelectric vibrator 3 by a temperature measuring unit including a temperature sensor 9 and an analog / digital (A / D) converter 4, and this measurement signal is stored in the storage unit 2 as a digital signal. Output. Note that all digits of the digital signal output from the A / D converter 4 are input to the storage unit 2. The piezoelectric oscillator 1 reads the correction value stored in the storage unit 2 in accordance with the digital signal and outputs it to the oscillation circuit 5, and the capacitance value of the capacitor array 6 provided in the oscillation circuit 5 is based on the correction value. Thus, the temperature of the piezoelectric vibrator 3 is compensated.

In addition to the above-described configuration, the piezoelectric oscillator 1 inputs a timing signal of 1 Hz, intermittently operates the temperature measurement unit every second, and reads the correction value in the storage unit 2 every second. By providing the control unit 7 to be performed automatically and the latch 8 for holding the correction value output from the storage unit 2, on average, the current consumption can be suppressed and the power consumption can be reduced.
In Patent Document 1, in order to increase the accuracy of temperature compensation control without increasing the memory capacity, temperature compensation is performed by interpolating a known control value between two adjacent temperatures to be controlled using a simple average value. A piezoelectric oscillator is disclosed.
JP-A-8-130411

  The temperature compensated oscillation circuit described above inputs all the digits of the digital signal output from the A / D converter to the storage unit, reads out the correction value corresponding to this digital signal one-to-one, and outputs it from the storage unit. Yes. Therefore, the storage unit has a problem that a large memory capacity is required. Further, the storage unit has a problem that the data writing time becomes long when the data amount of the correction values to be stored is large.

Further, the temperature compensated piezoelectric oscillator according to Patent Document 1 requires a compensation information readout circuit, an address addition circuit, a plurality of switch circuits, and the like, and thus there is a problem that the configuration of the entire oscillator becomes large.
An object of the present invention is to provide a temperature compensation method, a correction value determination circuit, and a temperature compensation oscillation circuit that perform temperature compensation using a storage unit having a small memory capacity.

  In the temperature compensation method according to the present invention, the temperature of the piezoelectric vibrator is intermittently measured by the temperature measurement unit, and the measurement result is output as a digital signal divided into the least significant bit and the upper bit, and the upper bit is output. An address value is input to the storage unit, and a correction value corresponding to the address value in a one-to-one manner is output during the intermittently measured time, and according to the least significant bit at an intermediate point in the intermittently measured time The correction value corresponding to the address value set in one-to-one is output, and the element value of the frequency adjustment element is adjusted based on the correction value to compensate the temperature of the piezoelectric vibrator. . In this case, the frequency adjusting element is a capacitance array or a frequency dividing stage, and the element value is a capacitance value or a frequency dividing number. The temperature compensation of the piezoelectric vibrator is connected to the subsequent stage of the circuit that oscillates the piezoelectric vibrator by adjusting the capacitance value of the capacitive array connected to the piezoelectric vibrator based on the correction value. Further, it is performed by adjusting the frequency dividing number of the frequency dividing stage based on the correction value.

  As a result, the least significant bit of the digital signal output from the temperature measurement unit is not used, and the high order bit is used to refer to the storage unit, so that the amount of correction value data stored in the storage unit is halved. And the memory capacity of the storage unit can be reduced. In addition, the amount of data written in which the address value and the correction value stored in the storage unit correspond one-to-one can be reduced, and the data writing time can be shortened. Furthermore, since the temperature measuring unit is operated intermittently and the temperature measuring unit is not operating at an intermediate time point during which the temperature measuring unit is operating intermittently, an increase in current consumption can be prevented.

  Further, in the temperature compensation method described above, the least significant bit used for reading the correction value at the intermediate time point of the intermittently measured time is the least significant bit of the digital signal output immediately after the temperature measurement. When the least significant bit is zero, the address value corresponding to the digital signal output immediately after temperature measurement is used as it is, and when the least significant bit is 1, the temperature measurement is performed immediately before. The upper address value of the digital signal to be output is set and used. As a result, the temperature-compensated oscillation circuit can output the correction value with reference to the storage unit even at an intermediate time point when the temperature measurement unit operates intermittently, so that all the digital signals output from the temperature measurement unit are stored. When the temperature compensation is performed, that is, when temperature compensation is performed with a data amount twice that of the present invention, the same temperature compensation effect can be obtained.

  The correction value determination circuit according to the present invention intermittently measures the temperature, inputs a temperature measurement unit that outputs the measurement result as a digital signal, and inputs the upper bits excluding the least significant bit of the digital signal, A counter that sets the upper bit according to the least significant bit and outputs it as an address value, and a correction value that is stored in a one-to-one correspondence with the address value in advance, is output from the counter. And a storage unit for reading out and outputting in accordance with the address value. In this case, a latch that holds the correction value can be connected to the output side of the storage unit.

  As a result, the least significant bit of the digital signal output from the temperature measurement unit is not used, and the high order bit is used to refer to the storage unit, so that the amount of correction value data stored in the storage unit is halved. And the memory capacity of the storage unit can be reduced. In addition, the amount of data written in which the address value and the correction value stored in the storage unit correspond one-to-one can be reduced, and the data writing time can be shortened. Furthermore, since the temperature measuring unit is operated intermittently and the temperature measuring unit is not operating at an intermediate time point during which the temperature measuring unit is operating intermittently, an increase in current consumption can be prevented.

  When the least significant bit is zero, the counter outputs the input upper bit as it is. When the least significant bit is 1, the counter sets and outputs the upper address value of the input upper bit. It is characterized by becoming. This is characterized in that the temperature is measured intermittently and is performed at an intermediate point in time. As a result, the temperature-compensated oscillation circuit can output the correction value with reference to the storage unit even at an intermediate time point when the temperature measurement unit operates intermittently, so that all the digital signals output from the temperature measurement unit are stored. The temperature compensation is equivalent to the case where the temperature compensation is performed with the double data amount, that is, the case where the temperature compensation is performed with twice the data amount.

  A temperature-compensated oscillation circuit according to the present invention includes the above-described correction value determination circuit, and an oscillation circuit that is connected to a piezoelectric vibrator and performs temperature compensation based on the correction value determined by the correction value determination circuit, The temperature measurement unit is characterized by measuring the temperature of the piezoelectric vibrator. Thereby, temperature compensation of the frequency temperature characteristic of the piezoelectric vibrator can be performed.

  The oscillation circuit includes a capacitance array that changes a capacitance value according to the correction value. It is possible to compensate the temperature of the piezoelectric vibrator by adjusting the oscillation frequency of the source oscillation by changing the capacitance value of the capacitors constituting the capacitance array.

  The temperature compensated oscillation circuit according to the present invention is characterized in that a timer circuit is connected to the output side of the oscillation circuit. As a result, the temperature compensated oscillation circuit can constitute a real time clock module of a capacity slow / slow type. The temperature compensated oscillation circuit operates the temperature measurement unit intermittently and switches the correction value at the intermediate time between the intermittent time and the intermittent time to compensate the temperature of the piezoelectric vibrator. Even if the amount of correction value data is halved, there is no significant error in timekeeping if averaged.

  Further, the temperature compensated oscillation circuit according to the present invention includes a timing circuit including a frequency dividing stage that adjusts the frequency division number based on the input correction value and changes the frequency of the clock signal output from the oscillation circuit. It is characterized by being connected to the output side of the oscillation circuit. As a result, the temperature compensated oscillation circuit can constitute a logic slow / rapid real-time clock module that adjusts the source oscillation output from the oscillation circuit at the frequency dividing stage. And the carry timing of the timing circuit can be made by the dividing stage. The temperature compensated oscillation circuit operates the temperature measurement unit intermittently and switches the correction value at the intermediate time between the intermittent time and the intermittent time to compensate the temperature of the piezoelectric vibrator. Even if the amount of correction value data is halved, there is no significant error in timekeeping if averaged.

  Hereinafter, the best embodiments of a temperature compensation method, a correction value determination circuit, and a temperature compensation oscillation circuit according to the present invention will be described. First, the first embodiment will be described. FIG. 1 is a block diagram of a correction value determination circuit. FIG. 2 is a block diagram of the temperature compensated oscillation circuit according to the first embodiment. The temperature-compensated oscillation circuit 10 includes a correction value determination circuit 20 and an oscillation circuit 42 that is connected to the piezoelectric vibrator 40 and performs temperature compensation based on the correction value determined by the correction value determination circuit 20.

  The correction value determination circuit 20 shown in FIG. 1 includes a temperature measurement unit 22, a counter 28, a storage unit 30, a latch 32, and a control unit 34. The temperature measurement unit 22 includes a temperature sensor 24 that measures the temperature of the piezoelectric vibrator 40 and an analog / digital (A / D) converter 26 that converts a measurement result output from the temperature sensor 24 from an analog signal to a digital signal. I have. A counter 28 and a control unit 34 are connected to the subsequent stage of the A / D converter 26.

  The counter 28 inputs upper bits of the digital signal output from the A / D converter 26 excluding the least significant bit. That is, in the case shown in FIG. 1, the A / D converter 26 has 8-bit outputs O7 to O0, and the counter 28 inputs the higher 7-bit outputs O7 to O1 among these 8 bits. The counter 28 outputs an address value when the upper bit is input.

  The control unit 34 inputs the least significant bit of the digital signal output from the A / D converter 26. That is, in the case shown in FIG. 1, the control unit 34 inputs the lowest output O0 among the 8-bit outputs O7 to O0 of the A / D converter 26. Then, the control unit 34 sets the address value output from the counter 28 according to the least significant bit information “0” or “1” and according to the temperature measurement timing. The control unit 34 receives a timing signal, intermittently operates the temperature measurement unit 22 and the counter 28 based on the timing signal, and controls the latch 32. And the control part 34 is a structure which inputs a 2 Hz timing signal, as FIG. 1 shows.

  A storage unit 30 is connected downstream of the counter 28. The storage unit 30 stores in advance a correction value associated with the address value in a one-to-one manner. When the address value is input from the counter 28, the correction value corresponding to the address value is read and output. . In addition, the memory | storage part 30 inputs the output A6-A0 from the counter 28, when FIG. 1 is shown. A latch 32 is connected to the subsequent stage of the storage unit 30. When the correction value output from the storage unit 30 is input, the latch 32 holds the correction value until the next correction value is input.

  The temperature compensated oscillation circuit 10 shown in FIG. 2 has a configuration in which an oscillation circuit 42 including a piezoelectric vibrator 40 is connected to the subsequent stage of the latch 32. The oscillation circuit 42 oscillates the piezoelectric vibrator 40 and includes a capacitance array 44 (frequency adjustment element) whose capacitance value (element value) changes according to the correction value. FIG. 3 is a circuit diagram illustrating the capacitor array. The capacitor array 44 includes a plurality of capacitors 46 having different capacitance values connected in parallel to the gate g side and the drain d side of the piezoelectric vibrator 40, and a switch 48 that is on / off controlled by a correction value output from the latch 32. Is connected to each capacitor 46 in series. The piezoelectric vibrator 40 may be a piezoelectric vibrator such as an AT cut, a tuning fork type piezoelectric vibrator, a surface acoustic wave resonator, or the like.

  Next, operations of the correction value determining circuit 20 and the temperature compensated oscillation circuit 10 will be described. First, the temperature measurement unit 22 operates intermittently based on a timing signal input to the control unit 34. That is, when the temperature sensor 24 intermittently measures the temperature of the piezoelectric vibrator 40, the measurement result is output as an analog signal. When an analog signal is input, the A / D converter 26 converts it into a digital signal and outputs it.

  The counter 28 inputs the upper bit of the digital signal output from the A / D converter 26 divided into the least significant bit and the upper bit. The control unit 34 inputs the least significant bit of the digital signal divided into the least significant bit and the most significant bit. When the temperature measuring unit 22 operates intermittently based on the timing signal, the counter 28 outputs the input upper bits as it is to the storage unit 30 as an address value. Further, at the intermediate point of the intermittent time when the temperature measuring unit 22 is intermittently operating, the counter 28 sets the address value according to the least significant bit information “0” or “1” input to the control unit 34. Set. The least significant bits used for this setting are those output from the A / D converter 26 to the control unit 34 when the temperature measurement unit 22 operates immediately before the intermediate timing. When the least significant bit is “0”, the address value output from the counter 28 is not adjusted, and the upper bit input to the counter 28 is directly output as the address value. On the other hand, when the least significant bit is “1”, when an upper bit input to the counter 28 is output as an address value, an address value one higher than this address value is output.

  When the timing signal is 2 Hz, the temperature sensor 24 and the A / D converter 26 operate every second, and the temperature of the piezoelectric vibrator 40 is measured every second. The upper bits of the digital signal output from the A / D converter 26 are input to the counter 28 and output as it is. Further, in the middle of every second when temperature measurement is performed, that is, 0.5 seconds after the temperature measurement, information “0” of the least significant bit output from the A / D converter 26 immediately before the temperature measurement is performed or The address value output from the counter 28 is set according to “1”.

  Thereafter, when an address value is input, the storage unit 30 reads a correction value corresponding to the address value on a one-to-one basis. That is, when the high-order bits input from the A / D converter 26 are directly input from the counter 28 as an address value, the correction value corresponding to the address value on a one-to-one basis is read by the storage unit 30. When an address value one higher than the address value based on the upper bits input from the A / D converter 26 is input from the counter 28, a correction value corresponding to the one-to-one correspondence is stored in the higher address value. Read at 30. Then, the storage unit 30 outputs the read correction value to the latch 32. When the correction value is input to the latch 32, the latch 32 holds the correction value until it is input and outputs it to the capacitor array 44 provided in the oscillation circuit 42. When a correction value is input, the capacitance array 44 adjusts the capacitance value by turning on or off each switch 48 according to the correction value. Thereby, the oscillation frequency of the piezoelectric vibrator 40 is adjusted. Thus, the clock signal output from the oscillation circuit 42 is output after temperature compensation.

  Since the correction value determination circuit 20 and the temperature compensation oscillation circuit 10 as described above do not use the least significant bit of the digital signal output from the A / D converter 26 and refer to the storage unit 30 using the upper bit, The amount of correction value data stored in the storage unit 30 can be halved, and the memory capacity of the storage unit 30 can be reduced. As a result, the amount of data written in which the address value and the correction value stored in the storage unit 30 are in one-to-one correspondence is reduced, and the data writing time can be shortened.

  Further, since the temperature of the piezoelectric vibrator 40 is compensated for in the intermittent time during which the temperature measuring unit 22 is operated based on the timing signal and in the intermediate time point of the intermittent time, it is necessary to provide a circuit for calculating the intermediate time point in the intermittent time. In addition, the configuration of the correction value determination circuit 20 and the temperature compensated oscillation circuit 10 can be reduced.

In addition, the temperature measuring unit 22 is intermittently operated to compensate for the temperature during the intermittent time and at the intermediate time of the intermittent time, so that all the digits of the digital signal output from the A / D converter 26 are obtained. Is input to the storage unit 30, that is, there is an effect of temperature compensation equivalent to the case where temperature compensation is performed with a data amount twice that of the present embodiment. This data is information stored in the storage unit 30 in such a manner that the address value and the correction value correspond to each other on a one-to-one basis.
Further, since the temperature measuring unit 22 operates only during the intermittent time and does not operate at an intermediate point in the intermittent time, the current consumption can be made equal to that of the conventional temperature compensated oscillation circuit that operates intermittently.

  Next, a second embodiment will be described. In the second embodiment, a configuration will be described in which a timer circuit is connected to the temperature-compensated oscillation circuit described in the first embodiment to form a real time clock module of a slow and rapid capacity type. For this reason, in the second embodiment, the description of the same components as those of the temperature compensated oscillation circuit described in the first embodiment is omitted, and the same reference numerals are given.

  FIG. 4 is a block diagram of a temperature compensated oscillation circuit according to the second embodiment. A time measuring circuit 50 is connected to the subsequent stage of the oscillation circuit 42 constituting the temperature compensated oscillation circuit 10. The time measuring circuit 50 includes a frequency dividing circuit 52 and a clock / calendar circuit 54. When the frequency dividing circuit 52 receives the clock signal output from the oscillation circuit 42, the frequency dividing circuit 52 divides the clock signal by a predetermined frequency and outputs it. The clock / calendar circuit 54 receives the clock signal output from the frequency dividing circuit 52 and displays or outputs a clock or calendar based on the clock signal.

  Thus, the temperature compensated oscillation circuit 10 can constitute a real time clock module. Since the temperature compensated oscillation circuit 10 intermittently operates the temperature sensor 24 and the A / D converter 26 and switches the correction value at the intermediate time between the intermittent time and the intermittent time, the temperature of the piezoelectric vibrator 40 is compensated. Even if the amount of data stored in the storage unit 30 is halved, a large error will not occur if averaged.

  Next, a third embodiment will be described. In the third embodiment, the correction value determination circuit described in the first embodiment, an oscillation circuit that is connected to the piezoelectric vibrator and performs temperature compensation based on the correction value determined by the correction value determination circuit, and a timing circuit are provided. A configuration in which a logic slow / rapid real-time clock module is formed will be described. For this reason, in the third embodiment, the description of the same components as those of the correction value determination circuit (temperature compensated oscillation circuit) described in the first embodiment is omitted or simplified, and the same reference numerals are given.

  FIG. 5 is a block diagram of a temperature compensated oscillation circuit according to the third embodiment. The temperature compensated oscillation circuit 10 includes a correction value determination circuit 20, an oscillation circuit 42 to which a piezoelectric vibrator 40 is connected, and a timer circuit 60. A timer circuit 60 is connected to the subsequent stage of the latch 32 and the subsequent stage of the oscillation circuit 42 constituting the correction value determining circuit 20. The timer circuit 60 includes a frequency dividing stage 62 (frequency adjusting element) and a clock / calendar circuit 64. The frequency dividing stage 62 receives the correction value output from the latch 32 and adjusts the frequency dividing number (element value) based on the correction value. The frequency dividing stage 62 receives the clock signal output from the oscillation circuit 42 and divides the frequency of the clock signal based on the frequency dividing number to adjust the rate. The clock / calendar circuit 64 receives the clock signal output from the frequency dividing stage 62 and displays or outputs a clock or calendar based on the clock signal.

  Thus, the temperature compensated oscillation circuit 10 can constitute a real time clock module. The temperature compensated oscillation circuit 10 operates the temperature sensor 24 and the A / D converter 26 intermittently, and switches the correction value at the intermediate time between the intermittent time and the intermittent time to compensate the temperature of the piezoelectric vibrator 40. Therefore, even if the amount of data stored in the storage unit 30 is halved, a large error will not occur if averaged.

It is a block diagram of a correction value determination circuit. 1 is a block diagram of a temperature compensated oscillation circuit according to a first embodiment. FIG. It is a circuit diagram explaining a capacity | capacitance array. It is a block diagram of the temperature compensation oscillation circuit which concerns on 2nd Embodiment. It is a block diagram of the temperature compensation oscillation circuit which concerns on 3rd Embodiment. It is a block diagram explaining the structure of the temperature compensation type piezoelectric oscillator which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ......... Temperature compensated oscillation circuit, 20 ......... Correction value determination circuit, 22 ......... Temperature measuring unit, 24 ......... Temperature sensor, 26 ......... Analog / digital (A / D) converter, 28 ... ...... Counter 30... Storage unit 34... Control unit 40... Piezoelectric vibrator 42.

Claims (8)

The temperature of the piezoelectric vibrator is intermittently measured by the temperature measurement unit, and this measurement result is output as a digital signal divided into the least significant bit and the upper bit,
The upper bits are input to the storage unit as an address value, and a correction value corresponding to the address value in a one-to-one manner is output at the intermittently measured time, and at the intermediate point of the intermittently measured time, the maximum value is output. A correction value corresponding to the address value set in accordance with the low-order bit is output on a one-to-one basis.
Adjusting the element value of the frequency adjustment element based on the correction value to compensate the temperature of the piezoelectric vibrator;
And a temperature compensation method. The least significant bit used for reading the correction value at the intermediate time point of the intermittently measured time is the least significant bit of the digital signal output by temperature measurement immediately before,
When the least significant bit is zero, the address value corresponding to the digital signal output by temperature measurement immediately before is used as it is,
When the least significant bit is 1, the upper address value of the digital signal to be output immediately after temperature measurement is set and used.
The temperature compensation method according to claim 1, wherein: A temperature measurement unit that intermittently measures the temperature and outputs the measurement result as a digital signal;
A counter that inputs higher bits excluding the least significant bit of the digital signal, sets the upper bit according to the least significant bit, and outputs it as an address value;
A storage unit that reads and outputs a correction value that is previously stored in a one-to-one correspondence with the address value according to the address value output from the counter;
A correction value determination circuit comprising:   When the least significant bit is zero, the counter outputs the input upper bit as it is. When the least significant bit is 1, the counter sets and outputs the upper address value of the input upper bit. The correction value determination circuit according to claim 3. A correction value determination circuit according to claim 3 or 4, and an oscillation circuit connected to a piezoelectric vibrator and performing temperature compensation based on the correction value determined by the correction value determination circuit,
The temperature-compensated oscillation circuit, wherein the temperature measurement unit measures the temperature of the piezoelectric vibrator.   The temperature-compensated oscillation circuit according to claim 5, wherein the oscillation circuit includes a capacitor array that changes a capacitance value according to the correction value.   The temperature-compensated oscillation circuit according to claim 6, wherein a timer circuit is connected to an output side of the oscillation circuit.   A timing circuit having a frequency dividing stage that adjusts the frequency division number based on the input correction value and changes the frequency of the clock signal output from the oscillation circuit is connected to the output side of the oscillation circuit. The temperature compensated oscillation circuit according to claim 5.

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