JP2010206443A - Temperature compensated piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a means for reducing temperature drift immediately after activation of a temperature compensated piezoelectric oscillator. <P>SOLUTION: A piezoelectric vibrating element 6 has frequency/temperature characteristics with a maximal value and a minimal value at a low-temperature side and a high-temperature side of an inflection point, respectively, and an IC component 8 includes: a temperature sensor 31 for sensing a temperature, a temperature compensation circuit 32 for compensating for the piezoelectric vibrating element, and a voltage controlled oscillation circuit 33 forming a voltage controlled oscillator together with the piezoelectric vibrating element. The temperature compensation circuit 32 is provided with: a circuit including a first-order component circuit and a third-order or higher-order component circuit; a signal processing circuit 35; and an adder circuit 36, and the compensation circuit 32 is adjusted in such a way that a relationship between a frequency compensation amount output from the voltage controlled oscillation circuit 33 and the temperature becomes less than a compensation amount for accurately compensating for the frequency/temperature characteristics of the piezoelectric vibrating element 6 and a frequency of the temperature compensated piezoelectric oscillator is decreased in accordance with temperature elevation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a temperature-compensated piezoelectric oscillator mainly used in mobile communication devices, and more particularly to a temperature-compensated piezoelectric oscillator that can improve its temperature compensation characteristics so that its function can be quickly demonstrated after power-on of the mobile communication device. The present invention relates to a piezoelectric oscillator.

In recent years, piezoelectric oscillators are used in many fields from communication devices such as mobile phones to consumer devices such as quartz watches due to their frequency stability, small size and light weight, robustness and low price. In particular, a temperature compensated piezoelectric oscillator (TCXO) that compensates for the frequency temperature characteristics of a piezoelectric vibrator is widely used in mobile phones and the like that require frequency stability.
As is well known, the TCXO is a piezoelectric oscillator that uses a variable capacitance element or the like to vary the load capacitance of the oscillation circuit in accordance with a temperature change. The load capacity of the oscillation circuit is controlled so as to change in reverse to the frequency change of the piezoelectric vibrator due to temperature fluctuation, and the frequency change of the piezoelectric vibrator is canceled and compensated. In recent years, the oscillation circuit including a variable capacitor has been made into a one-chip IC in accordance with a demand for miniaturization of a piezoelectric oscillator.

Japanese Patent Laying-Open No. 2008-252812 (Patent Document 1) discloses a temperature compensated oscillator that shortens the time from start-up or temperature change until it stabilizes at a predetermined frequency change amount. The temperature-compensated oscillator 70 includes a crystal resonator element 72, an integrated circuit element 74 that performs temperature compensation of the crystal resonator element 72, a container body 75 that houses the crystal resonator element 72 and the integrated circuit element 74, and a container body 75.
And a lid 78 for sealing.
The crystal resonator element 72 has a frequency characteristic in which the relationship between the temperature and the frequency change amount is a cubic function. The integrated circuit element 74 includes a temperature sensor 81 that detects temperature, a temperature compensation circuit 82 that includes a cubic function generation circuit and a primary component generation circuit, an oscillation circuit 83 that oscillates the crystal oscillation element 72, and an addition circuit 84. And storage means 85.

The container body 75 has an H-shaped structure in which a rectangular ring-shaped frame portion 77 is integrally formed on both main surfaces of the substrate portion 76, and a connection pad for the crystal resonator element 72 is provided on the bottom surface of one recess (upper side). P is provided. Also, a pad T for mounting the integrated circuit element 74 is provided on the bottom surface of the other concave portion (lower side). Part of the pad T is connected to the connection pad P by the internal wiring H provided in the container body 75.
And the external connection terminal G.
The temperature characteristics after the temperature compensation are such that the frequency change amount (df / f) when the temperature is 25 ° C. is 0 (pp
m), and the frequency change (df / f) is 0.1 (ppm) as the temperature t increases by 1 ° C.
Within a gentle slope. That is, the maximum gradient is a gradient in which the frequency change amount decreases by 0.1 (ppm) with respect to an increase in temperature of 1 ° C. In addition, the application temperature range in which the frequency change amount decreases by 0.1 (ppm) as the temperature increases by 1 ° C. is, for example, −40 ° C. to 80 ° C.
It is disclosed that it may be in the range of 25 ° C to 40 ° C.
JP 2008-252812 A

Patent Document 1 discloses a temperature compensation method for a temperature-compensated crystal oscillator using a crystal resonator whose frequency changes in a cubic function with respect to temperature change. Japanese Patent Application Laid-Open No. 2004-228561 shows a method for adjusting temperature so that the primary component of the temperature compensation circuit is adjusted so that the relationship between the temperature and the frequency change amount decreases as the temperature increases.
However, in order to accurately represent the frequency temperature characteristics of an actual piezoelectric resonator, for example, an AT-cut crystal resonator, an error occurs in the cubic function related to temperature, and recently, a polynomial including a term of a fourth-order component or more related to temperature is required. It has become. That is, a circuit configuration of a primary component circuit, a tertiary component circuit, and a quaternary component or higher is required as a compensation circuit. Therefore, there is a problem that the method of adjusting only the primary component as in Patent Document 1 is insufficient to satisfy the recent demand for a temperature compensated piezoelectric oscillator.
The present invention has been made to solve the above-described problem, and provides a temperature compensated oscillator in which a frequency drift after power-on is reduced by using a circuit that includes a fourth-order component or more in the temperature compensation circuit. It is in.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1] A temperature-compensated piezoelectric oscillator according to the present invention includes a piezoelectric vibration element, an IC component, and a package main body that accommodates the piezoelectric vibration element and the IC component in order to reduce frequency drift after power-on. A temperature-compensating piezoelectric oscillator comprising a lid for sealing one opening of the package body, wherein the piezoelectric vibration element has a maximum value and a minimum value on a low temperature side and a high temperature side of the inflection point, respectively. The IC component has a temperature sensor that senses temperature, a temperature compensation circuit that compensates for a frequency change due to the temperature of the piezoelectric vibration element, and voltage control in cooperation with the piezoelectric vibration element. A voltage-controlled oscillation circuit that forms a type oscillator, and the temperature compensation circuit includes a circuit including a primary component circuit and a third-order or higher-order component circuit, a signal processing circuit, an adder circuit, The voltage regulation The relationship between the frequency compensation amount output from the type oscillation circuit and the temperature is smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the frequency of the temperature compensation type piezoelectric oscillator decreases as the temperature rises. Thus, the temperature compensation type piezoelectric oscillator is characterized by adjusting the processing circuit and the compensation circuit.

Since the coefficient of the circuit including the primary component circuit of the temperature compensation circuit and the higher-order component circuit of the third or higher order and the processing circuit are adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature increases,
The frequency drift of the temperature compensated piezoelectric oscillator is reduced, and the temperature compensated piezoelectric oscillator is, for example, G
When used in a PS device, the GPS device functions immediately after the power is turned on.

Application Example 2 In the temperature compensated piezoelectric oscillator, the relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the temperature compensation is performed as the temperature rises. The temperature-compensated piezoelectric oscillator according to Application Example 1, wherein the third-order component circuit is adjusted so that the frequency of the piezoelectric oscillator decreases.

Since the third-order component circuit of the temperature compensation circuit is adjusted so that the frequency of the temperature compensation piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensation piezoelectric oscillator decreases. It is easy to adjust only one circuit of the temperature compensation circuit. When the temperature compensated piezoelectric oscillator is used in, for example, a GPS device, there is an effect that it can be used immediately after the power is turned on.

[Application Example 3] In the temperature compensated piezoelectric oscillator, the temperature compensated piezoelectric oscillator is configured such that the relationship between the temperature and the frequency compensation amount is less than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element. As the frequency increases, the frequency of the temperature-compensated piezoelectric oscillator decreases so that the primary and 3
The temperature-compensated piezoelectric oscillator according to Application Example 1, wherein the second component circuit is adjusted.

Since the primary and tertiary component circuits of the temperature compensation circuit are adjusted so that the frequency of the temperature compensation piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensation piezoelectric oscillator decreases.
Since the two circuits of the temperature compensation circuit are adjusted, it is possible to adjust to a desired characteristic. When the temperature compensated piezoelectric oscillator is used in a GPS device, it can be used immediately after the power is turned on. is there.

Application Example 4 In the temperature-compensated piezoelectric oscillator, the relationship between the temperature and the frequency compensation amount is less than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the temperature compensation is performed as the temperature increases. 2. The temperature compensated piezoelectric oscillator according to claim 1, wherein the third-order or higher-order component circuit is adjusted so that the frequency of the piezoelectric oscillator decreases.

Since the third-order or higher-order component circuit of the temperature compensation circuit is adjusted so that the frequency of the temperature compensation type piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensation type piezoelectric oscillator decreases. The frequency temperature characteristic can be adjusted to a desired characteristic, and when the temperature compensated piezoelectric oscillator is used in a GPS device, it can be used immediately after startup.

Application Example 5 In the temperature compensated piezoelectric oscillator, the relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the temperature compensation is performed as the temperature rises. The temperature-compensated piezoelectric oscillator according to application example 1, wherein a signal obtained from the temperature sensor is processed by the processing circuit so that a frequency of the piezoelectric oscillator decreases, and a secondary component is adjusted.

Since the secondary component of the temperature compensation circuit is adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensated piezoelectric oscillator decreases. Adjustment of the secondary component is extremely easy by adjusting only the memory circuit of the processing circuit. When the temperature compensated piezoelectric oscillator is used in a GPS device, it can be used immediately after the power is turned on.

[Application Example 6] In the temperature compensated piezoelectric oscillator, the relationship between the temperature and the frequency compensation amount accurately compensates the frequency-temperature characteristic of the piezoelectric vibration element in the temperature range from room temperature to the minimum value of the piezoelectric vibration element. The temperature compensated piezoelectric device according to any one of application examples 1 to 5, wherein the temperature compensated piezoelectric oscillator is adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature rises. It is an oscillator.

The temperature compensation circuit third-order component circuit, first-order and third-order component circuit, third-order or more so that the frequency of the temperature-compensated piezoelectric oscillator decreases as the temperature increases from room temperature to the minimum value of the piezoelectric vibration element. Therefore, the frequency drift of the temperature compensated piezoelectric oscillator is reduced. This temperature compensated piezoelectric oscillator is GPS
When used in an apparatus, there is an effect that it can be used immediately after startup.

1 is a schematic sectional view showing the structure of a temperature compensated piezoelectric oscillator 1 according to the present invention. 1 is a block circuit diagram showing a circuit configuration of a temperature compensated piezoelectric oscillator 1. FIG. The block circuit diagram which shows the structure of a temperature compensation circuit. (A) is the figure which shows the elapsed time and frequency deviation of the conventional temperature compensation type piezoelectric oscillator, (b) is the figure which shows the temperature compensation method of this invention, (c) shows the temperature rise of a piezoelectric vibration element and IC components. Figure. (A)-(e) is a figure explaining the process of temperature compensation. (A) is a temperature characteristic of the frequency compensation amount produced | generated by a temperature compensation circuit, (b) is a figure which shows the frequency temperature characteristic of a temperature compensation type | mold piezoelectric oscillator. FIG. 6A is a graph showing temperature characteristics of compensation voltage and FIG. 5B is a diagram showing frequency temperature characteristics of a temperature compensated piezoelectric oscillator when the value of the primary component circuit is changed. FIG. 6A is a graph showing temperature characteristics of compensation voltage and FIG. 5B is a diagram showing frequency temperature characteristics of a temperature-compensated piezoelectric oscillator when the value of a circuit having a third or higher order component is changed. FIG. 6A is a graph showing temperature characteristics of compensation voltage and FIG. 5B is a diagram showing frequency temperature characteristics of a temperature compensated piezoelectric oscillator when the value of a secondary component is changed. FIG. 6A is a graph showing temperature characteristics of compensation voltage and FIG. 5B is a diagram showing frequency temperature characteristics of a temperature compensated piezoelectric oscillator when a value of a fifth-order component circuit is changed. FIG. 6 is a schematic cross-sectional view showing the structure of a conventional temperature compensated piezoelectric oscillator. The block circuit diagram which shows the circuit structure of the conventional temperature compensation type | mold piezoelectric oscillator.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic sectional view showing the structure of a temperature compensated piezoelectric oscillator 1 according to an embodiment of the present invention, and FIG. 2 is a block diagram showing the circuit configuration of the temperature compensated piezoelectric oscillator 1. The temperature compensated piezoelectric oscillator 1 includes a piezoelectric vibration element 6 and
An IC component 8, a package main body 10 that houses the piezoelectric vibration element 6 and the IC component 8, and a lid 20 that seals one opening of the package main body 10 are provided. Package body 1
0 has a two-story structure type (H type) as shown in the sectional view of FIG.
The piezoelectric vibration element 6 and the IC component 8 are mounted in the recesses 14a and 14b provided on the upper surface and the lower surface of 0, respectively, and the recess 14a on the upper surface is hermetically sealed with the lid 20.
The package body 10 of the temperature compensated piezoelectric oscillator 1 has recesses 14a and 14 on the upper and lower surfaces, respectively.
A plurality of insulating containers 10a each having a vertical cross-sectional shape b are disposed on the bottom surface of each stepped portion 10b projecting along two opposing sides of the rectangular annular outer bottom surface of the insulating container 10a. And a mounting terminal 15. In order to mount the piezoelectric vibration element 6 in the upper surface side recess 14a, 2
Two upper surface side internal pads 12a are provided. In order to mount the IC component 8 having a temperature sensor, a temperature compensation circuit, an oscillation circuit, etc., a lower surface side internal pad 12b is disposed on the ceiling surface of the lower surface side recess 14b. And the internal wiring 13 which conduct | electrically_connects between each mounting terminal 15, the upper surface side internal pad 12a, and the lower surface side internal pad 12b is formed.

In the temperature-compensated piezoelectric oscillator 1, the piezoelectric vibration element 6 is connected and fixed to the upper surface side internal pad 12 a of the package body 10 via the conductive adhesive 16, and the upper surface side recess 14 a is made of, for example, a metal lid 20. Hermetically seal with. Then, the lower surface side internal pad 12b of the package body 10 is connected
The C component 8 is connected and fixed using a gold bump 17 or the like. When the upper surface side recess 14a is hermetically sealed, the inside of the upper surface side recess 14a is evacuated or contains an inert gas (
For example, N ₂ ) is enclosed and sealed.
When the temperature compensated piezoelectric oscillator 1 is mounted on the printed board, the mounting terminals 15 provided on the bottom surface of each stepped portion 10b are connected and fixed to the lands formed on the printed board via solder.

The circuit configuration of the temperature compensated piezoelectric oscillator 1 includes a piezoelectric vibration element 6 and an IC component 8 as shown in the block circuit diagram of FIG. The piezoelectric vibration element 6 includes a metal thin film (excitation electrodes 6a and 6b) formed by vapor-depositing metal in vacuum on both main surfaces of a piezoelectric substrate, for example, an AT-cut quartz substrate, and the excitation electrodes 6a and 6b to the end of the piezoelectric substrate. The part is provided with an extraction electrode. In the example of the AT cut vibration element 6, various frequency temperature characteristics can be obtained depending on the cutting angle of the quartz substrate. In the temperature compensated piezoelectric oscillator 1, the maximum value and the minimum value are located on the low temperature side and the high temperature side, respectively, from the inflection point. The piezoelectric vibration element 6 having the frequency temperature characteristic is used. Frequency-temperature characteristics of the general piezoelectric vibrating element 6, the inflection point temperature of t _0, polynomial in temperature _{t (Cn (t-t 0} ) n + Cn-1 (t-
t ₀ ) ⁿ⁻¹ +... + C3 (t−t ₀ ) ³ + C2 (t−t ₀ ) ² + C1 (t−t ₀ )).
The IC component 8 includes a temperature sensor 31 such as a thermistor or a diode that senses temperature.
And a temperature compensation circuit 32 that compensates for a frequency change due to the temperature of the piezoelectric vibration element 6 and a variable capacitance element (varicap diode, nMOS-FET, pMOS-FET, etc.) in cooperation with the piezoelectric vibration element 6. A voltage controlled oscillation circuit 33 forming a controlled oscillator and an amplifier circuit 34
And.

FIG. 3 is a block circuit diagram illustrating the temperature compensation circuit 32. The temperature compensation circuit 32 is a primary component circuit 32 a, a third component circuit 32 b, a circuit having a fourth component or higher, and a processing circuit that processes the signals of the primary to n-order component circuit 32 a based on the signal from the temperature sensor 31. 35 and an adder circuit 36 for adding the signals of the primary to n-order component circuit 32a. As is well known, since the secondary component that generates the temperature supplementary voltage can be formed by shifting the inflection point temperature t ₀ , the IC component 8 is not included as an electronic circuit.
Based on the signal from the temperature sensor 31, the processing device 35 calculates a compensation amount necessary to compensate the temperature characteristic of the piezoelectric vibration element 6, and outputs each constant to the first to n-th order component circuits. Primary to n
The adder circuit 36 adds the outputs of the next component circuit, and the output voltage Vc of the adder circuit 36 is applied to the variable capacitance element of the voltage controlled oscillator 33.

FIG. 4A is a diagram for explaining compensation of a conventional temperature-compensated piezoelectric oscillator. The frequency deviation (Δf / f) is plotted with the elapsed time t (sec) after startup or after temperature change as the horizontal axis. The vertical axis is shown. A general temperature compensation method for a temperature-compensated piezoelectric oscillator has a sufficiently long time after startup (t2
), The frequency change amount α (t2) at an arbitrary temperature of the piezoelectric vibration element is measured, and the compensation amount β (t2) by the temperature compensation circuit is β (t2) to compensate for this change amount α (t2). ) = Α
Each component (A1, A3, A4, A5,...) Of the temperature compensation circuit is determined so as to be (t2).
In the transition period t1 after the start-up or after the temperature change, the compensation amount β (t1) of the temperature compensation circuit is generated at the temperature Tβ sensed by the temperature sensor. However, as shown in FIG. 4C, the transition period (t
The temperature Tα exhibited by the piezoelectric vibration element (Xtal) in 1) is Tα <Tβ, and the frequency fluctuation amount α (t1) of the piezoelectric vibration element 6 is smaller than the compensation amount β (t1). As a result, the compensation amount becomes excessive in the transition period t1, and so-called frequency drift occurs.

In FIG. 4A, β (t) is a compensation amount by the temperature compensation circuit, α (t) is a change amount of the piezoelectric vibration element, and γ (t) is a frequency of the temperature compensated piezoelectric oscillator after the temperature compensation is performed. It is. After starting,
Alternatively, the compensation amount (Δf / f) indicated by the curve β (t) becomes constant when the time ta elapses after the temperature change. Further, when the time tb elapses, the frequency fluctuation amount (Δf / f) indicated by the curve α (t)
Is constant. The time is ta <tb, and after the elapsed time tb, α (t) = β (t
)
However, the frequency fluctuation amount α (t) of the piezoelectric vibration element 6 and the compensation amount β by the temperature compensation circuit 32.
Since the amount of change with elapsed time t is different from (t), a temperature compensated piezoelectric oscillator (TCXO)
The frequency γ (t) does not become 0, but rises rapidly at the beginning and converges to 0 as time passes.
The curve γ (t) is TCXO depending on the difference between the temperature sensed by the temperature sensor 31 and the temperature exhibited by the piezoelectric vibration element 6 to be compensated at the elapsed time (t) after startup or after changing to a certain temperature.
The frequency γ (t) changes rapidly from the 0 line, reaches a peak, and then reaches 0 after the elapse of time tb.
The characteristic returns to the line. Such a temperature-compensated piezoelectric oscillator having rapidly changing frequency characteristics is not suitable for a device that instantaneously receives information from a plurality of satellites such as GPS.

The reason why the frequency change of the conventional temperature compensated piezoelectric oscillator becomes as indicated by γ (t) in FIG. 4A will be specifically described. First, consider a case where the temperature-compensated piezoelectric oscillator is a single unit and the structure is, for example, a two-story structure type (H type) as shown in FIG.
The IC component 8 disposed in the lower side recess 14b of the temperature compensated piezoelectric oscillator generates heat rapidly after the internal active element is activated, and the IC component 8 is extremely small, so that the temperature of the entire chip increases rapidly. The temperature sensor 31 built in the IC component 8 instantly senses the temperature rise of the IC component 8, and the IC component 8
The temperature compensation circuit 32 built in the component 8 generates a compensation voltage, and adds the compensation voltage to the variable capacitance element of the voltage-controlled oscillator 33 to generate a compensation amount (Δf / f). This compensation amount (Δf / f)
Is β (t) in FIG. 3A and converges to a constant value in a short time.

On the other hand, heat conduction to the piezoelectric vibration element has two paths, and the first path is conducted from the IC component 8 which is a heat generation source to the internal wiring 13 via the lower surface side internal pad 12b, and the upper surface side inner pad 12 is transmitted.
This is a path that passes through a to the piezoelectric substrate via the piezoelectric vibration element 6 extraction electrode and excitation electrodes 6a and 6b. The second path is conducted from the IC component 8 which is a heat generation source to the insulating container 10a of the package body 10 through the lower surface side internal pad 12b, and from the substrate of the insulating container 10a through the gas (N ₂ ) in the upper recess 14a. This is a path that conducts to the piezoelectric vibration element 6. Since the path through the internal wiring 13 of the first path is made of metal, the thermal conductivity is high. However, since the path is thin or thin, the thermal conductivity is small. Further, the heat conduction through the insulating container 10a of the package body 10 and the gas (N ₂ ) has a small heat conductivity of the gas, and thus the heat conduction amount of this path is not large. For these reasons, there is a temperature difference between the temperature sensed by the temperature sensor 31 of the IC component and the temperature exhibited by the piezoelectric vibration element 6, and it takes time for the two temperatures to be equal.
Therefore, immediately after starting the temperature compensated piezoelectric oscillator, the temperature exhibited by the piezoelectric vibration element 6,
There is a difference between the temperature sensed by the temperature sensor 31 and the compensation amount to be compensated for the piezoelectric vibration element 6 is different from the compensation amount generated from the temperature compensation circuit. for that reason,
A frequency drift occurs immediately after startup.

When a temperature-compensated piezoelectric oscillator is mounted on a printed circuit board of a communication device and the communication device is activated, the printed circuit board is equipped with a CPU, a power supply circuit, etc., and these electronic components generate heat immediately after the activation, and the printed circuit board The temperature rises rapidly. The temperature compensated piezoelectric oscillator mounted on the printed circuit board is affected by heat from the printed circuit board side in addition to the heat generation of its own IC components. If the temperature-compensated piezoelectric oscillator is of a two-story structure type (H type), the IC component 8 is mounted on the lower surface side recess 14b of the package body 10, so that the printed circuit board is connected via the mounting terminal 15 and the internal wiring 13. The heat conduction from the path to be conducted is short and the temperature of the IC component 8 rises rapidly. In addition, the temperature of the IC component 8 increases due to radiant heat from the printed circuit board.
The temperature sensor 31 quickly detects this temperature increase. However, the conduction of heat to the piezoelectric vibration element 6 has a long path through the internal wiring 13, and the heat conduction through the package body 10 also takes time. The temperature sensed by the temperature sensor and the temperature of the piezoelectric vibration element There is a temperature difference between
Even in an actual use state, a frequency drift as shown in FIG.

In order for the GPS system to achieve high positioning accuracy, the temperature stability of the temperature compensated piezoelectric oscillator is required to be high. In particular, in the case of a portable GPS, the frequency stability of a reference frequency source mounted on the GPS is limited, and the receiver moves. Therefore, generally, the Doppler frequency is measured by calculating the frequency shift of the carrier frequency based on the Doppler effect. A vector of the moving speed of the communication device is detected using the Doppler frequency and a plurality of GPS satellites, and a frequency shift (shift due to the Doppler effect) accompanying the movement is corrected. At the same time, the frequency error of the reference oscillator in the communication device is also obtained and corrected. However, there is a limit to the range that can be corrected, and if the frequency error of the reference oscillator is larger than the specified value, it cannot be corrected.
PS devices cannot capture signals from satellites. Therefore, there is a problem that it takes time until the temperature compensation type temperature distribution becomes uniform until the signal is captured.

A method for adjusting the temperature compensation circuit 32 of the temperature compensated piezoelectric oscillator (TCXO) 1 according to the present invention will be described with reference to FIG. Α (t2) shown in FIG. 4B is the frequency fluctuation amount of the piezoelectric vibrating element 6 when the heat reaches a steady state after the time t2 has passed at an arbitrary temperature. β
(T2) is a frequency compensation amount by the temperature compensation circuit 32 after the time t2 has elapsed, and β (t
2) = α (t2). The compensation method of the present invention is a method for compensating the piezoelectric vibration element 6 using a frequency compensation amount β ′ (t2) smaller than the frequency compensation amount β (t2). That is, the temperature compensation circuit 32 is adjusted to generate the frequency compensation amount β ′ (t2). Frequency compensation amount β ′ (
If t2) can be generated, the frequency fluctuation γ ′ (t) of TCXO1 shown in FIG. 4 (b) also reduces the frequency drift in the transition period t1, and can satisfy the GPS specifications over the entire time. Become.

A temperature compensation method for the temperature compensated piezoelectric oscillator 1 according to the present invention will be described with reference to the drawings.
FIG. 5A shows a piezoelectric vibration element 6 with the vertical axis representing frequency deviation (Δf / f) and the horizontal axis representing temperature (T ° C.).
It is a curve which shows the frequency temperature characteristic of. The broken line in FIG. 5B is the temperature characteristic of the output voltage Vc of the temperature compensation circuit 32 for accurately compensating the frequency temperature characteristic in FIG. As shown by the solid line in FIG. 5B, the adjustment method of the present invention is based on the absolute value of the maximum and minimum values of the compensation voltage Vc with respect to the dashed compensation voltage curve for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element 6. The characteristic is that compensation is performed by decreasing the value.
FIG. 5C shows the capacitance C-voltage Vc characteristics of the variable capacitance element used in the voltage controlled oscillation circuit 33. The temperature T-capacitance C characteristic shown in FIG. 5D is a capacitance characteristic generated when the output voltage Vc characteristic of the temperature compensation circuit 32 shown in FIG. 5B is added to the variable capacitance element. FIG. 5 (e)
Is a load capacity characteristic showing the relationship between the load capacity C of the piezoelectric vibration element 6 and the frequency shift. When the piezoelectric vibration element 6 is loaded with a capacity having a temperature T-capacitance C characteristic indicated by a solid line in FIG. 5D, FIG.
The frequency compensation characteristic indicating the relationship between the temperature T and the frequency compensation amount (Δf / f) shown in FIG. By adding the frequency compensation characteristic and the frequency temperature characteristic exhibited by the piezoelectric vibration element, a frequency temperature characteristic that decreases downward as the temperature increases, which is indicated by a solid line in FIG. 6B, is obtained. The broken line in FIG. 6B is the conventional frequency temperature characteristic when the temperature compensation voltage shown by the broken line in FIG. 5B is used. The solid line in FIG. 6B is a piezoelectric vibration element using a temperature compensation voltage smaller than the absolute value of the temperature compensation voltage indicated by the solid line in FIG. 5B, that is, the maximum value and the minimum value of the temperature compensation voltage indicated by the wavy line. 6 is a frequency-temperature characteristic in the case of compensating 6 and the frequency-temperature characteristic of the present invention is the temperature T
Decrease to the right with the increase.

FIG. 7A shows the temperature obtained by simulating the output voltage Vc obtained from the temperature compensation circuit 32 when the constant value of the primary component circuit of the temperature compensation circuit 32 of the temperature compensated piezoelectric oscillator 1 is changed. It is a curve of T-compensation voltage Vc. A curve indicated by D2 is an optimum value of the compensation voltage Vc curve, and is a case where the temperature compensation circuit 32 is set so that the frequency temperature characteristic becomes almost zero in a predetermined temperature range (for example, −30 ° C. to 85 ° C.). . A curve D1 is an output voltage curve when the constant value of the primary component circuit is set larger than an appropriate value, and a curve D3 is set too small.
FIG. 7B shows the output voltage Vc (D1, D2, D) of the temperature compensation circuit 32 as shown in FIG.
3 is a frequency temperature characteristic of the temperature compensated piezoelectric oscillator 1 obtained based on 3). A curve D2 in FIG. 7B is a frequency temperature characteristic obtained by compensating the piezoelectric vibration element 6 using the output voltage curve D2 in FIG. 7A, and has a flat characteristic. By changing the constant value of the primary component circuit of the temperature compensation circuit 32 from an appropriate value from D1 and D3 in FIG. 7B, a frequency temperature characteristic that falls to the right or a frequency temperature characteristic that rises to the right as the temperature increases. You can see that
The diagram of the frequency-temperature characteristic shown in FIG. 7B is a simulation that the frequency deviation (Δf / f) greatly fluctuates due to the change in the output voltage Vc of the temperature compensation circuit 32. A large number of curves between the curves D2 and D1 can be obtained by appropriately setting the memory provided in the processing circuit, and the optimum characteristics in consideration of the structure of the temperature-compensated piezoelectric oscillator, the temperature rise of the printed board to be mounted, etc. Should be set to be.
In addition, an example of the specification of the frequency temperature characteristic actually used for GPS is a temperature range (−30 ° C. to
85 ° C.) and about ± 0.5 ppm.

FIG. 8A is a simulation of the output voltage Vc obtained from the temperature compensation circuit 32 when the constant value of the circuit of the third or higher order component of the temperature compensation circuit 32 of the temperature compensated piezoelectric oscillator 1 is changed. The curve indicated by D2 has a frequency temperature characteristic within a predetermined temperature range (for example, −30 ° C. to 85 ° C.).
Thus, the output voltage Vc when the temperature compensation circuit 32 is set to an optimum value so as to be substantially zero. A curve D1 is an output voltage Vc curve when a constant value of a circuit having a third or higher order component is set to be larger than an appropriate value, and a curve D3 is set to be too small.
FIG. 8B shows the output voltage Vc (D1, D2, D3) of the temperature compensation circuit 32 as shown in FIG.
2 is a frequency temperature characteristic of the temperature compensated piezoelectric oscillator 1 obtained based on the above. A curve D2 in FIG. 8B is a frequency-temperature characteristic in which the piezoelectric vibration element 6 is compensated using the output voltage curve D2 in FIG. 8A, and has a flat characteristic. From FIG. 8B, it can be seen that by changing the constant value of the circuit of the third or higher order component of the temperature compensation circuit 32, a frequency temperature characteristic that decreases to the right or a frequency temperature characteristic that increases to the right is obtained as the temperature increases.
Since the third-order or higher-order component circuit of the temperature compensation circuit is adjusted so that the frequency of the temperature compensation type piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensation type piezoelectric oscillator decreases. The frequency temperature characteristic can be adjusted to the desired characteristic, and the temperature compensated piezoelectric oscillator
When used in a PS device, there is an effect that it can be used immediately after startup.

FIG. 9A is a simulation of the output voltage Vc obtained from the temperature compensation circuit 32 when the constant value of the secondary component of the temperature compensation circuit 32 of the temperature compensated piezoelectric oscillator 1 is changed. D2
Is a curve of the output voltage Vc when the temperature compensation circuit 32 is set to an optimum value so that the frequency temperature characteristic becomes substantially zero in a predetermined temperature range (for example, −30 ° C. to 85 ° C.).
A curve D1 is an output voltage curve when the constant value of the secondary component is set to be larger than an appropriate value, and a curve D3 is set to be too small.
As is well known, the secondary component can be changed by appropriately selecting the temperature-output voltage characteristics of the temperature sensor 31 stored in the processing circuit. This corresponds to shifting the inflection point t ₀ when the temperature compensation circuit 32 is configured by a polynomial of the temperature (t−t ₀ ) including the inflection point temperature t ₀ .
FIG. 9B shows the output voltage Vc (D1, D2, D3) of the temperature compensation circuit 32 shown in FIG.
2 is a frequency temperature characteristic of the temperature compensated piezoelectric oscillator 1 obtained based on the above. A curve D2 in FIG. 9B is a frequency temperature characteristic obtained by compensating the piezoelectric vibration element 6 using the output voltage curve D2 in FIG. 9A, and has a flat characteristic. It can be seen from FIG. 9 (b) that by changing the constant value of the secondary component of the temperature compensation circuit 32, a frequency temperature characteristic that decreases to the right or a frequency temperature characteristic that increases to the right is obtained as the temperature increases.
Since the secondary component of the temperature compensation circuit is adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature increases, the frequency drift of the temperature compensated piezoelectric oscillator decreases. Adjustment of the secondary component is extremely easy by adjusting the memory circuit of the processing circuit.
When used in a PS device, there is an effect that it can be used immediately after the power is turned on.

FIG. 10A is a simulation of the output voltage Vc obtained from the temperature compensation circuit 32 when the constant value of the fifth-order component circuit of the temperature compensation circuit 32 of the temperature compensated piezoelectric oscillator 1 is changed. A curve indicated by D2 is a curve of the output voltage Vc when the temperature compensation circuit 32 is set so that the frequency temperature characteristic becomes substantially zero in a predetermined temperature range (for example, −30 ° C. to 85 ° C.). A curve D1 is an output voltage curve when the compensation is set to an excessive value above the appropriate value, and a curve D3 is set to an excessively small value.
FIG. 10B shows the output voltage Vc (D1, D2, D) of the temperature compensation circuit 32 shown in FIG.
3 is a frequency temperature characteristic of the temperature compensated piezoelectric oscillator 1 obtained based on 3). FIG. 10 (b)
A curve D2 is a frequency-temperature characteristic obtained by compensating the piezoelectric vibrating element 6 using the output voltage curve D2 of FIG. From FIG. 10B, it can be seen that by changing the constant value of the fifth-order component circuit of the temperature compensation circuit 32, a frequency temperature characteristic that decreases to the right or a frequency temperature characteristic that increases to the right is obtained as the temperature increases.

In the above, each circuit of the temperature compensation circuit and some combinations of the circuits have been described. However, the third-order component circuit of the temperature compensation circuit, or the first-order component circuit and the third-order component circuit are adjusted, and the temperature increases as the temperature increases. You may adjust so that the frequency of a compensation type piezoelectric oscillator may decrease.
By adjusting in this way, the frequency drift of the temperature compensated piezoelectric oscillator is reduced, and if the temperature compensated piezoelectric oscillator is used in a GPS device, it can be used immediately after the power is turned on.

In the above, each circuit of the temperature compensation circuit and some combinations of the circuits have been described.
The frequency temperature characteristic of the temperature compensated piezoelectric oscillator may be adjusted to a desired characteristic by adjusting all of the second component circuit, the third and higher order component circuit, and the second component.
Since the coefficient of the circuit including the primary component circuit of the temperature compensation circuit and the higher-order component circuit of the third or higher order and the processing circuit are adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature increases,
The frequency drift of the temperature compensated piezoelectric oscillator is reduced and the temperature compensated piezoelectric oscillator
When used in the S device, there is an effect that the GPS device functions immediately after the power is turned on.
The temperature compensation circuit third-order component circuit, first-order and third-order component circuit, third-order or more so that the frequency of the temperature-compensated piezoelectric oscillator decreases as the temperature increases from room temperature to the minimum value of the piezoelectric vibration element. The higher order component circuit, the second order component, the first order, and the higher order component circuit of the third order or higher may be adjusted.
Practically, if the temperature compensated piezoelectric oscillator is adjusted so that the frequency decreases as the temperature rises at room temperature or higher, the temperature compensated piezoelectric oscillator can be used immediately after startup if used in a GPS device. is there.

DESCRIPTION OF SYMBOLS 1 ... Temperature compensation type | mold piezoelectric oscillator, 6 ... Piezoelectric vibration element, 8 ... IC component, 10 ... Package body,
DESCRIPTION OF SYMBOLS 10a ... Insulation container, 10b ... Step part, 12a ... Upper surface side internal pad, 12b ... Lower surface side internal pad, 13 ... Internal wiring, 14a, 14b ... Recess, 15 ... Mounting terminal, 16 ... Conductive adhesive agent,
DESCRIPTION OF SYMBOLS 17 ... Gold bump, 20 ... Cover body, 31 ... Temperature sensor, 32 ... Temperature compensation circuit, 33 ... Voltage control type oscillation circuit, 34 ... Amplification circuit, 35 ... Processing circuit, 36 ... Addition circuit, (alpha) (t) ... Piezoelectric Frequency change amount of vibration element, β (t): compensation amount by compensation circuit, γ (t): frequency of temperature compensated piezoelectric oscillator

Claims (6)

A temperature-compensated piezoelectric oscillator comprising: a piezoelectric vibration element; an IC component; a package body that houses the piezoelectric vibration element and the IC component; and a lid that seals one opening of the package body. ,
The piezoelectric vibration element has a frequency temperature characteristic having a maximum value and a minimum value on the low temperature side and the high temperature side of the inflection point, respectively.
The IC component includes a temperature sensor that senses temperature, a temperature compensation circuit that compensates for a frequency change due to the temperature of the piezoelectric vibration element, and a voltage-controlled oscillation that forms a voltage-controlled oscillator in cooperation with the piezoelectric vibration element. A circuit,
The temperature compensation circuit includes a circuit including a primary component circuit and a third-order or higher-order component circuit, a signal processing circuit, and an addition circuit.
The relationship between the frequency compensation amount output from the voltage controlled oscillation circuit and the temperature is less than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the temperature compensated piezoelectric oscillator according to the temperature rise A temperature-compensated piezoelectric oscillator, wherein a processing circuit and a compensation circuit are adjusted so that the frequency decreases. The relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature rises. 2. The temperature compensated piezoelectric oscillator according to claim 1, wherein a second component circuit is adjusted. The relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the frequency of the temperature compensated piezoelectric oscillator is decreased as the temperature rises. 2. The temperature compensated piezoelectric oscillator according to claim 1, wherein the second and third component circuits are adjusted. The relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the frequency of the temperature compensated piezoelectric oscillator decreases as the temperature rises. The temperature-compensated piezoelectric oscillator according to claim 1, wherein a higher-order component circuit of the second order or higher is adjusted. The relationship between the temperature and the frequency compensation amount is made smaller than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element, and the temperature of the temperature compensated piezoelectric oscillator decreases as the temperature rises. The temperature-compensated piezoelectric oscillator according to claim 1, wherein a signal obtained from a sensor is processed by the processing circuit and a secondary component is adjusted. The relationship between the temperature and the frequency compensation amount in a temperature range from room temperature to a minimum value of the piezoelectric vibration element is less than the compensation amount for accurately compensating the frequency temperature characteristic of the piezoelectric vibration element,
6. The temperature compensated piezoelectric oscillator according to claim 1, wherein the temperature compensated piezoelectric oscillator is adjusted so that the frequency of the temperature compensated piezoelectric oscillator decreases with an increase in temperature.

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