JP2010219738A - Temperature-compensated piezoelectric oscillator and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a temperature-compensated piezoelectric oscillator for improving temperature stability of frequencies in piezoelectric vibrators further, and to provide electronic apparatus. <P>SOLUTION: The temperature-compensated piezoelectric oscillator 1 includes a piezoelectric oscillation section 10, and the piezoelectric oscillation section 10 includes a variable capacitor 110, that is connected to one side of I/O of the piezoelectric vibrator 100 and has capacity changing according to an applied voltage; and a plurality of capacitors 130 that are provided, being selectively connectable to the other side of the I/O of the piezoelectric vibrator 100 and serve as the load capacitance of the piezoelectric vibrator 100. Furthermore, the temperature-compensated piezoelectric oscillator 1 includes: a selection connection processing section 20 that selectively connects the capacitor corresponding to temperature information in the plurality of capacitors 130, to at least one side of the I/O of the piezoelectric vibrator 100 and performs selection connection processing for compensating temperature characteristics of the piezoelectric vibrator 100; and a compensation voltage generating section 30 for applying the compensation voltage for compensating temperature characteristics of the piezoelectric vibrator 100, corresponding to the temperature information, to the variable capacitor 110. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a temperature compensated piezoelectric oscillator, an electronic device, and the like.

  The resonance frequency of the AT-cut crystal resonator has a cubic function curve characteristic with respect to temperature, as indicated by the alternate long and short dash line in FIG. 9A or FIG. 11A. When an oscillation circuit is configured using this crystal resonator, the output frequency of the oscillation circuit also has a cubic function curve characteristic with respect to temperature. The temperature compensated crystal oscillator (TCXO) is a temperature compensation that suppresses the frequency change of the oscillation circuit with respect to the temperature change by changing the capacitance (load capacitance CL) on the oscillation circuit side so as to cancel the temperature characteristics of the crystal resonator. Has been done.

  Two types of temperature compensation methods are known: a digital method and an analog method. The principle of temperature compensation uses the characteristic that the oscillation frequency changes when the load capacitance CL of the oscillation circuit is changed. By changing the load capacitance CL with respect to the temperature so as to cancel out the frequency temperature characteristic of the crystal resonator, the temperature change in the frequency of the oscillation circuit can be suppressed. The method of changing the load capacity CL is roughly classified into two types depending on whether it is digital or analog. As shown in FIG. 8, the digital method in Patent Document 1 changes the load capacity CL by switching the capacity bank 210 provided in the oscillation circuit using the switch 200 that operates following the temperature change based on the memory information. It is a method to make it. The oscillation frequency temperature characteristic after temperature compensation by the digital method is as shown by a solid line in FIG. As shown in FIG. 10, in the analog methods of Patent Documents 2 and 3, a voltage that changes in the third order with respect to temperature (hereinafter referred to as a compensation voltage) is applied to a variable capacitance element 300 provided in an oscillation circuit. In this method, the capacitance is changed by applying 310. The temperature characteristic after the temperature compensation by the analog method is as shown by a solid line in FIG. There are other methods of analog compensation, which is an example.

  The digital method has a problem that the frequency changes discontinuously when the capacitor bank 210 is switched. In order to eliminate the discontinuity, it is necessary to provide a large number of capacitor banks 210 with finer capacitance values. However, since the switch 200 and the digital memory 220 for controlling the switch 200 increase, the IC size increases. On the other hand, in the analog method, the compensation voltage generation circuit 310 generates a voltage that varies with temperature, and applies it to the variable capacitance element 300 in the oscillation circuit, so that the load capacitance CL of the oscillation circuit becomes the temperature. On the other hand, the temperature is compensated by changing in an analog manner. Further, the compensation voltage generation circuit 310 is designed so that the compensation voltage curve can be adjusted by using the memory 320, and when the product is commercialized, the compensation voltage curve is obtained by using the memory 320 to obtain the temperature characteristics of the crystal unit 330. Adjust to be optimal for canceling out. In this way, temperature compensation is individually performed so that the frequency deviation of the oscillation circuit becomes smaller with respect to the temperature. The analog method can change the capacitance of the variable capacitance element 300 continuously, and the frequency change does not become discontinuous with respect to the temperature change.

  Although TCXO is used as a reference frequency for mobile phones and has different specifications depending on the system, accuracy of several ppm, for example, ± 1.5 ppm to ± 3 ppm is required at Ta = −30 ° C. to + 85 ° C. However, recently, in TCXO used for mobile phones with GPS function, for example, frequency accuracy of ± 0.5 ppm has been required.

  Quartz vibrators have individual temperature variations due to variations in cut angles. Furthermore, there are variations in the ICs constituting the oscillation circuit and the compensation voltage generation circuit.

  According to the digital method, since the frequency changes discontinuously as shown in FIG. 9B at the moment when the temperature changes and the setting of the capacity bank changes, it is not preferable in terms of the cellular phone system.

  In the analog method, the temperature compensation is individually performed so that the frequency temperature deviation of the oscillation output frequency with respect to the temperature is small. However, although the adjustment is performed individually, the IC adjustment capability (resolution) Due to the measurement error or the like, it is not easy to achieve high accuracy (for example, within ± 0.5 ppm) by the conventional analog method as shown in FIG.

  As shown in the prior art documents, studies have been made to increase the accuracy of the compensation voltage in order to improve the accuracy of the IC. However, since the current consumption increases and there is a balance with the production yield, it is further increased. There was a problem that accuracy was difficult.

Japanese Patent Laid-Open No. 5-218738 No. 2004/025824 JP 2007-325033 A

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, a temperature-compensated piezoelectric oscillator in which the temperature stability of the output frequency of the piezoelectric oscillation circuit is further improved. In addition, an electronic device can be provided.

  (1) A temperature-compensated piezoelectric oscillator according to the present invention includes an amplifier, a piezoelectric vibrator, and a variable capacitance element that is connected to at least one input / output side of the piezoelectric vibrator and whose capacitance changes according to an applied voltage. A plurality of capacitive elements provided so as to be selectively connectable to at least one input / output side of the piezoelectric vibrator, a piezoelectric oscillation unit that outputs an oscillation signal, means for outputting temperature information, A selective connection processing unit that selectively connects a capacitive element corresponding to the temperature information from the capacitive element to at least one of the input and output of the piezoelectric vibrator, and performs a selective connection process for temperature compensation of the frequency of the oscillation signal; And a compensation voltage generator for applying a compensation voltage for temperature compensating the frequency of the oscillation signal corresponding to the temperature information to the variable capacitance element.

  Examples of the piezoelectric vibrator include a vibrator using a single crystal material such as a crystal vibrator, a ceramic vibrator, a lithium niobate vibrator, and a lithium tantalate vibrator, a zinc oxide piezoelectric thin film vibrator, and an aluminum oxide piezoelectric thin film. A vibrator using a piezoelectric thin film such as a vibrator may be used.

  The variable capacitance element is an element whose capacitance changes according to the applied voltage, and examples thereof include a MOS varactor and a variable capacitance diode (varicap).

  As a means for outputting temperature information, for example, a temperature sensor may be used. In this case, the compensation voltage generator generates a voltage (temperature compensation) that changes according to the output of the temperature sensor in order to compensate for the temperature characteristics of the piezoelectric vibrator. The compensation voltage generator applies a voltage that continuously changes with respect to the temperature change to the variable capacitance element in order to cancel the frequency-temperature characteristic of the piezoelectric vibrator. Thus, analog control is performed by continuously changing the capacitance of the variable capacitance element. The compensation voltage generator may be configured to have an adjustment function for adjusting so as to obtain an optimum compensation voltage curve in order to successfully cancel out the temperature characteristics of the piezoelectric vibrator by changing the capacitance of the oscillation circuit. In this case, the voltage may be individually adjusted according to the temperature characteristics of each piezoelectric vibrator, and the setting information may be stored in the memory.

  The selective connection processing unit performs selective connection processing for selectively connecting a capacitive element corresponding to temperature information from a plurality of capacitive elements to at least one input / output side of the piezoelectric vibrator in order to compensate for temperature characteristics of the piezoelectric vibrator. . This selective connection process may be performed based on information stored in the memory, for example. Specifically, information for selective connection of a plurality of capacitive elements selected in association with temperature information is stored in a memory so as to compensate for temperature characteristics of the piezoelectric vibrator. Then, the capacitor element selected based on the temperature information from the data stored in the memory may be specified, and the selective connection process may be performed.

  As described above, the compensation voltage generator of the present invention can compensate the temperature characteristics of the piezoelectric vibrator in an analog manner by applying a compensation voltage corresponding to temperature information to the variable capacitance element. In addition to this, in the temperature compensated piezoelectric oscillator of the present invention, the selective connection processing unit performs the selective connection processing of the capacitive element corresponding to the temperature information, and compensates the temperature characteristics of the piezoelectric vibrator by the selected capacitive element. can do.

  Therefore, the temperature compensated piezoelectric oscillator according to the present invention performs analog temperature compensation by a compensation voltage and digital temperature compensation by switching a capacitive element in accordance with the temperature, so that It is possible to realize a temperature compensated piezoelectric oscillator with further improved frequency temperature stability.

  (2) In this temperature-compensated piezoelectric oscillator, the piezoelectric oscillation unit includes a plurality of switches connected in series to the plurality of capacitive elements, and the plurality of switches are at least one of the input and output of the piezoelectric vibrator. The selective connection processing unit may perform selective connection processing of the plurality of capacitive elements by turning on / off the plurality of switches.

  (3) In this temperature-compensated piezoelectric oscillator, the selective connection processing unit may further temperature-compensate the frequency of the oscillation signal temperature-compensated by the compensation voltage output from the compensation voltage generation unit. You may make it perform the selective connection process of a capacitive element.

  In the temperature-compensated piezoelectric oscillator of the present invention, the capacitive element is further provided with a temperature region having inferior compensation accuracy with respect to the frequency temperature characteristic of the piezoelectric oscillation circuit compensated in an analog manner by the temperature compensation by the compensation voltage output from the compensation voltage generator. The digital compensation used can be performed. In the conventional digital compensation, in order to compensate the wide temperature characteristic (for example, ± 15 ppm) of the piezoelectric vibrator to ± 0.5 ppm, for example, a large number of fine capacity banks are prepared, and the operating temperature range (for example, −30 degrees Celsius to +85 degrees Celsius). It was necessary to control the capacity with fine resolution and a large amount of memory and a large amount of memory. However, according to the temperature compensated piezoelectric oscillator of the present invention, the frequency temperature characteristic once analog-compensated (for example, temperature compensated to ± 1.5 ppm) is digitally compensated therefrom (for example, ± 1. ± 0.5 ppm can be realized. Therefore, by combining with analog compensation and digitally compensating the amount that cannot be compensated by analog, the amount of digital compensation is reduced, and high accuracy is realized with a smaller capacity bank and fewer memory circuits than before. Can do. In addition, since the amount of digital compensation is small, frequency jumps at the time of memory switching, which is a problem in conventional digital compensation, can be suppressed.

  Therefore, according to the present invention, temperature compensation of the frequency of the piezoelectric oscillator can be performed with high accuracy with a small IC size.

  (4) In this temperature-compensated piezoelectric oscillator, the temperature information is based on a low temperature region below a first temperature included in the operable temperature range of the piezoelectric vibrator and the first temperature included in the operating temperature range. It is included in at least one of the high temperature regions higher than the second high temperature, and the selective connection processing unit performs the selective connection processing in at least one of the low temperature region and the high temperature region based on the temperature information. Good.

  (5) In this temperature compensated piezoelectric oscillator, the first temperature may be 0 degrees Celsius.

  (6) In this temperature compensated piezoelectric oscillator, the second temperature may be 60 degrees Celsius.

  (7) In the temperature compensated piezoelectric oscillator, the means for outputting the temperature information includes a temperature sensor for detecting a temperature associated with the piezoelectric vibrator, and the temperature information is output by the temperature sensor. Also good.

  (8) The present invention is an electronic device including the temperature compensated piezoelectric oscillator according to any one of the above.

2 is a configuration example of a temperature compensated piezoelectric oscillator in the present embodiment. FIG. 2A shows temperature characteristics of the piezoelectric vibrator. FIG. 2 (B) shows temperature characteristics of the frequency of the piezoelectric oscillator after temperature compensation by the compensation voltage generator. FIG. 2C shows the temperature characteristics of the output frequency of the piezoelectric oscillation circuit after temperature compensation by adjusting the capacitor bank. 6 shows another configuration example of the temperature compensated piezoelectric oscillator according to the present embodiment. 6 shows another configuration example of the temperature compensated piezoelectric oscillator according to the present embodiment. 3 is a specific configuration example of a temperature compensated piezoelectric oscillator according to the present embodiment. An example of an electronic apparatus using the temperature compensated piezoelectric oscillator according to the present embodiment. An example of an electronic apparatus using the temperature compensated piezoelectric oscillator according to the present embodiment. Conventional digital compensation method. FIG. 9A shows the frequency temperature characteristics of the piezoelectric oscillator before temperature compensation and the frequency temperature characteristics of the piezoelectric oscillator after temperature compensation by the digital compensation method of the prior art. FIG. 9B is an enlarged view of FIG. Conventional analog compensation method. FIG. 11A shows a frequency temperature characteristic of the piezoelectric oscillator before temperature compensation and a frequency temperature characteristic of the piezoelectric oscillator after temperature compensation by the analog compensation method of the prior art. FIG. 11B is an enlarged view of FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Temperature Compensated Piezoelectric Oscillator FIG. 1 is a diagram for explaining the configuration of a temperature compensated piezoelectric oscillator.

  The temperature compensated piezoelectric oscillator 1 of the present embodiment includes a piezoelectric oscillation unit 10, a selective connection processing unit 20, a compensation voltage generation unit 30, an A / D converter 50, a temperature sensor 40 as a means for outputting temperature information, a memory 70, The digital memory 90 is included.

  The piezoelectric oscillation unit 10 includes an amplifier 140, a feedback resistor 150, a piezoelectric vibrator 100, a variable capacitance element 110, a plurality of switches 120, and a plurality of capacitance elements 130.

  In the piezoelectric oscillation unit 10, the amplifier 140, the piezoelectric vibrator 100, and the feedback resistor 150 are connected in parallel, and the output of the amplifier 140 is connected to the feedback resistor 150 and the input of the piezoelectric vibrator 100 that operates as a dielectric reactance. Connected. Further, the piezoelectric oscillation unit 10 includes a variable capacitance element 110 and a plurality of capacitance elements 130 to constitute a Colpitts oscillation circuit, and performs an oscillation operation.

  The variable capacitance element 110 is connected to at least one input / output side of the piezoelectric vibrator 100. In this embodiment, the piezoelectric vibrator 100 is connected to the output side. The variable capacitance element 110 is an element whose capacitance changes when a voltage is applied, and the frequency of the piezoelectric oscillator 10 can be controlled by changing the capacitance of the variable capacitance element 110. Examples of the variable capacitance element 110 include a variable capacitance diode (varicap) and a MOS type varactor.

  The plurality of capacitive elements 130 are connected to at least one side of the input / output of the piezoelectric vibrator 100. In this embodiment, the piezoelectric vibrator 100 is connected to the input side. The plurality of capacitive elements 130 are provided corresponding to the plurality of switches 120, and the selected capacitive element becomes the load capacitance of the piezoelectric oscillator 10 when the corresponding switch is turned on.

  The selective connection processing unit 20 performs the selective connection processing of the capacitive elements by performing on / off control of the plurality of switches 120 so as to compensate the temperature characteristics of the piezoelectric oscillator 10 in accordance with the temperature information of the temperature sensor 40. .

  The compensation voltage generator 30 generates a compensation voltage that compensates for the temperature characteristics of the piezoelectric vibrator 100 according to the temperature information of the temperature sensor 40, and applies the compensation voltage to the variable capacitor 110. In the temperature-compensated piezoelectric oscillator 1 of the present embodiment, the compensation voltage generator 30 applies a compensation voltage set so that the frequency deviation of the piezoelectric oscillator 10 is small with respect to the temperature change to the variable capacitance element 110, and the temperature In contrast, analog control is performed in which the capacitance of the variable capacitance element is continuously changed.

  As a result, the compensation voltage generator 30 applies the compensation voltage to the variable capacitance element 110 in the oscillation circuit, so that the load capacitance CL changes so as to cancel the temperature characteristics of the piezoelectric vibrator 100. As a circuit, it is possible to obtain a frequency temperature characteristic in which a frequency change with respect to temperature is reduced. The compensation voltage generating circuit 30 can adjust the compensation voltage curve by using the memory 70, and when the product is commercialized, the compensation voltage curve is optimized to cancel the temperature characteristic of the piezoelectric vibrator 100 by using the memory 70. You may adjust.

  Here, the compensation voltage generator 30 represents a curve representing the temperature characteristics of the oscillation frequency of the piezoelectric oscillator 10 when no compensation is performed, by an approximate n-order function, and outputs a compensation voltage that is an approximate n-order function to perform temperature compensation. You may do it.

  For example, when outputting a compensation voltage that is an approximate n-order function, a zero-order component generation unit, a primary component generation unit according to temperature information, a third-order component generation unit, a fourth-order component generation unit,... The outputs of the n−1 order component generator and the n order component generator may be added and output.

  According to the temperature compensated piezoelectric oscillator 1 of the present embodiment, the selective connection processing unit 20 performs on / off control of the plurality of switches 120 corresponding to the temperature information. Accordingly, the load capacitance CL of the piezoelectric oscillator 10 is changed by switching the plurality of capacitive elements 130 provided corresponding to the plurality of switches 120. In this way, temperature compensation can be performed so that the frequency deviation of the piezoelectric oscillator 10 becomes smaller with respect to temperature changes. Note that in the series connection of the plurality of capacitive elements 130 and the plurality of switches 120, the arrangement of the plurality of capacitive elements 130 and the switches 120 may be interchanged.

  FIG. 2A is a graph showing the temperature characteristics of the frequency deviation of the piezoelectric oscillator when there is no compensation using the piezoelectric vibrator 100. FIG. 2B is a graph showing temperature characteristics of the frequency of the piezoelectric oscillator 10 when temperature compensation is performed by the compensation voltage generator 30. According to FIG. 2B, the temperature characteristics without compensation using the piezoelectric vibrator 100 are compensated to about ± 1.5 ppm. Since the temperature characteristics of the piezoelectric vibrator change as the temperature becomes lower and higher, the compensation accuracy deteriorates at lower and higher temperatures.

  For this reason, in the temperature compensated piezoelectric oscillator 1 of the present embodiment, the temperature characteristics of the frequency of the piezoelectric oscillator 10 compensated by the compensation voltage output from the compensation voltage generating unit 30 are converted into a plurality of capacitive elements 130 by the selective connection processing unit 20. To compensate further.

  FIG. 2C shows the frequency temperature of the piezoelectric oscillator 10 when the temperature compensation is performed by changing the load capacitance CL by switching the switch after the temperature compensation by the compensation voltage generator 30 in FIG. 2B. It is a graph showing the characteristic. Accuracy is obtained even at low and high temperatures, and it is stabilized to ± 0.5 ppm.

  Details of the processing of the selective connection processing unit 20 will be described below.

  As shown in FIG. 2B, according to the temperature compensation by the compensation voltage generator 30, for example, the temperature characteristic can be ± 0.5 ppm from 0 degrees Celsius to 60 degrees Celsius. For example, only when the temperature is lower than 0 degrees Celsius and when the temperature is higher than 60 degrees Celsius, the capacity bank may be switched by a switch, and temperature compensation may be performed by changing the load capacity CL.

  Further, the selective connection processing unit 20 performs the case where the temperature information is equal to or lower than the first temperature (for example, 0 degrees Celsius) included in the operable temperature range of the piezoelectric vibrator 100 and the second (for example, higher than the first temperature). The on / off control as the selective connection control of the capacitive element may be performed at least in the case where the temperature is equal to or higher than 60 degrees Celsius.

  As described above, according to the temperature compensated piezoelectric oscillator 1 of this embodiment, the temperature characteristics of the piezoelectric vibrator 100 are compensated as shown in FIG. 2B when the temperature compensation is performed by the compensation voltage generator 30. The Therefore, the temperature compensation by the change of the capacitor bank is performed on the temperature characteristics of the piezoelectric oscillator 10 in FIG. 2B, so that highly accurate temperature compensation can be performed over a wide temperature band.

  Specifically, as shown in FIG. 2 (C), the discontinuity due to switching of the switches as seen in the conventional digital method as shown in FIG. 9 (B) was also improved, and was seen in the conventional analog method. The deterioration in accuracy of temperature compensation on the low temperature side and the high temperature side as shown in FIG. 11B is also improved.

  As described above, in the conventional digital system, in order to compensate the temperature characteristic of the piezoelectric vibrator 100 from ± 15 ppm to ± 0.5 ppm, it is necessary to compress it to about 3/100. According to the piezoelectric oscillator 1, ± 1.5 ppm after temperature compensation by the compensation voltage generator 30 may be compressed to about １ ／.

  Therefore, according to the temperature-compensated piezoelectric oscillator 1 of the present embodiment, a plurality of switches 120 and a plurality of switches are used, compared to the case where temperature compensation is performed so that the temperature characteristics of the piezoelectric vibrator become ± 0.5 ppm only by the conventional digital method. The number of capacitive elements 130 can be reduced, and the memory for controlling them can also be reduced.

  As shown in FIG. 3, in the temperature compensated piezoelectric oscillator 1 of the present embodiment, the connection location of the compensation voltage generator 30 and the variable capacitance element 110, the plurality of switches 120, and the plurality of capacitance elements 130 are selectively connected. The same effect can be obtained even if the connection place with the unit 20 is replaced. Specifically, the compensation voltage generation unit 30 and the variable capacitance element 110 are connected to the output side of the piezoelectric vibrator 100, and the plurality of switches 120, the plurality of capacitance elements 130, and the selective connection processing unit 20 are connected to the piezoelectric vibrator 100. A similar effect can be obtained by connecting to the input side.

  Further, the variable capacitance element 110 and the plurality of capacitance elements 130 may be connected to one of the input and output sides of the piezoelectric vibrator 100.

  As shown in FIG. 4, in the temperature compensated piezoelectric oscillator 1 of the present embodiment, the compensation voltage generation unit 30, the variable capacitance element 110, the plurality of capacitance elements 130, the plurality of switches 120, the selective connection processing unit 20, The same effect can be obtained by connecting the piezoelectric vibrator 100 to the input side and the output side of the piezoelectric vibrator 100.

  These circuit configurations are examples, and are not limited thereto.

  FIG. 5 is a more specific configuration example of the temperature compensated piezoelectric oscillator 1 of the present embodiment.

  The temperature compensated piezoelectric oscillator 1 according to the present embodiment includes a piezoelectric oscillation unit 10, a compensation voltage generation unit 30, a temperature sensor 40, an A / D converter 50, a selective connection processing unit 20, and a first storage unit 80. The second storage unit 60 may be included. The same components as those in FIG. 1 are denoted by the same reference numerals, and the description thereof is omitted.

  The temperature sensor 40 detects the temperature and outputs the detected result. The temperature sensor 40 outputs an analog signal that depends on the temperature.

  As described above, the compensation voltage generator 30 changes the compensation voltage so as to compensate the temperature characteristics of the piezoelectric vibrator 100 in association with the output of the temperature sensor 40 and applies the compensation voltage to the variable capacitance element 110.

  In addition, the compensation voltage generating unit 30 is adjusted so that the output voltage is optimally compensated for the temperature characteristics of the piezoelectric vibrator 100, and the information is stored in the memory area 82 of the first storage unit 80. At the time of oscillation, the circuit operates and temperature compensation is performed under the conditions stored in the memory area 82 of the first storage unit 80. The first storage unit 80 corresponds to the memory 70 of FIG.

  Specifically, the compensation voltage is adjusted as follows.

  The reference voltage, the offset voltage, the gain of the operational amplifier, and the like inside the circuit constituting the compensation voltage generating unit 30 are designed so as to be adjusted in advance, and based on the information stored in the memory area 82 of the first storage unit 80. An on / off changeover switch is provided inside and an adjustment circuit that can change a voltage value, an amplifier gain (resistance ratio), and the like is used.

  The compensation voltage generator 30 outputs a compensation voltage according to the voltage of the temperature sensor 40, and the slope and offset value of this output voltage can be changed by an adjustment circuit. As a result, the piezoelectric vibrator 100 can be individually adapted to variations in characteristics.

  Here, the memory area 82 of the first storage unit 80 stores information for determining circuit constants such as the gain of the amplifier, and the circuit state of the compensation voltage generator does not change with respect to temperature changes.

  The A / D converter 50 converts the detection result of the temperature sensor 40 into digital data.

  The second storage unit 60 stores a switch selection table 62 that defines the correspondence between temperature information and information on switches to be selected from among the plurality of switches 120 included in the piezoelectric oscillation unit 10. For example, when the temperature information represents minus 10 degrees Celsius, the switch information to be turned on is selected from the switch selection table 62 corresponding to the temperature information of minus 10 degrees Celsius. Note that the second storage unit 80 corresponds to the digital memory 90 of FIG.

  The switch information in the switch selection table 62 may be bus data.

  The selective connection processing unit 20 decodes data based on the switch selection table 62 and performs a selective connection process for turning on the switch corresponding to the decoded value among the plurality of switches 120. As a result, the combination of the plurality of capacitive elements 130 changes, and the load capacitance CL changes.

  As described above, the temperature-compensated piezoelectric oscillator 1 according to the present embodiment has a function of applying the compensation voltage generated by the compensation voltage generation circuit 30 to the variable capacitance element 110 and changing the load capacitance CL in an analog manner to perform temperature compensation. In addition, by having the function of changing the load capacitance CL digitally using the selective connection processing unit 20 and the plurality of capacitive elements 130, the frequency temperature characteristics of the piezoelectric oscillator 10 as shown in FIG. 2C can be realized. .

2. Electronic Device The notebook computer 1000 of FIG. 6 and the mobile phone 2000 of FIG. 7 are external views showing an example of the electronic device of the temperature compensated piezoelectric oscillator 1 according to the present invention. With the temperature compensated piezoelectric oscillator 1 of the present embodiment, a highly reliable electronic device can be realized.

  The electronic device in which the temperature compensated piezoelectric oscillator 1 according to the present invention is incorporated is not limited to a digital still camera, a wristwatch, and a portable information device, but an electronic notebook, pager, POS terminal, IC card, minidisc player, liquid crystal projector, Multimedia compatible personal computer (PC) and engineering workstation (EWS), notebook personal computer, word processor, TV, viewfinder type or monitor direct view type video tape recorder, electronic notebook, electronic desk calculator, car navigation system, Various electronic devices such as a device equipped with a touch panel and a watch are conceivable.

  In addition, this invention is not limited to this embodiment, A various deformation | transformation implementation is possible within the range of the summary of this invention.

  The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 Temperature compensation type | mold piezoelectric oscillator, 10 Piezoelectric oscillation part, 20 Selection connection process part 20, 30 Compensation voltage generation part, 40 Temperature sensor, 50 A / D converter, 60 2nd memory | storage part, 62 Switch selection table, 80 1st Storage unit, 100 piezoelectric vibrator, 110 variable capacitance element, 120 plural switches, 130 plural capacitance elements, 200 switch, 210 capacitance bank, 220 digital memory, 300 variable capacitance element, 310 compensation voltage generation circuit, 320 memory, 330 crystal oscillator, 140 amplifier, 150 feedback resistor, 1000 notebook computer, 2000 mobile phone

Claims (8)

An amplifier;
A piezoelectric vibrator;
A variable capacitance element that is connected to at least one side of the input / output of the piezoelectric vibrator and whose capacitance changes according to an applied voltage;
A plurality of capacitive elements provided so as to be selectively connectable to at least one side of the input / output of the piezoelectric vibrator;
A piezoelectric oscillation unit that outputs an oscillation signal, and
Means for outputting temperature information;
Selective connection processing for selectively connecting a capacitive element corresponding to the temperature information from the plurality of capacitive elements to at least one of input and output of the piezoelectric vibrator, and performing selective connection processing for temperature compensation of the frequency of the oscillation signal And
A compensation voltage generator that applies a compensation voltage to the variable capacitor to compensate the temperature of the oscillation signal in response to the temperature information;
A temperature-compensated piezoelectric oscillator comprising: In claim 1,
The piezoelectric oscillation unit is
A plurality of switches each connected in series to the plurality of capacitive elements;
The plurality of switches are:
It is connected between at least one side of the input / output of the piezoelectric vibrator and the ground,
The selective connection processing unit
A temperature-compensated piezoelectric oscillator, wherein the plurality of capacitive elements are selectively connected by turning on / off the plurality of switches. In claim 1 or 2,
The selective connection processing unit
A temperature-compensated piezoelectric oscillator characterized by performing a selective connection process of the plurality of capacitive elements so as to further temperature-compensate the frequency of the oscillation signal that has been temperature-compensated by the compensation voltage output from the compensation voltage generator. . In any one of Claims 1 thru | or 3,
The temperature information is
Included in at least one of a low temperature region below a first temperature included in the operable temperature range of the piezoelectric vibrator and a high temperature region above a second temperature higher than the first temperature included in the operating temperature range,
The selective connection processing unit
A temperature-compensated piezoelectric oscillator, wherein the selective connection processing is performed in at least one of the low temperature region and the high temperature region based on the temperature information. In claim 4,
The first temperature is
A temperature-compensated piezoelectric oscillator characterized by being 0 degrees Celsius. In claim 4 or 5,
The second temperature is
A temperature-compensated piezoelectric oscillator having a temperature of 60 degrees Celsius. In any one of Claims 1 thru | or 6.
The means for outputting temperature information is
A temperature sensor for detecting a temperature associated with the piezoelectric vibrator;
The temperature information is
A temperature compensated piezoelectric oscillator, wherein the temperature sensor outputs.   An electronic apparatus comprising the temperature compensated piezoelectric oscillator according to claim 1.

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