JP2010193134A - Temperature compensation type piezoelectric oscillator - Google Patents

Abstract

An object of the present invention is to reduce the influence of a heating element.
A piezoelectric vibrator, an oscillation circuit that controls an oscillation frequency of the piezoelectric vibrator based on a control voltage, and a first temperature detector that detects a temperature and outputs a first voltage.
And a second temperature detector T2 that detects the temperature and outputs the second voltage V2, and a difference that outputs a third voltage V3 that is a difference voltage between the first voltage V1 and the second voltage V2. An adder circuit 130 that outputs a circuit 120 and a fourth voltage V4 that is the sum of the first voltage V1 and the third voltage V3.
And a temperature-compensated piezoelectric oscillator 1 including a control voltage generation circuit 140 that generates a control voltage VC based on the fourth voltage V4.
[Selection] Figure 1

Description

  The present invention relates to a temperature compensated piezoelectric oscillator.

In a small electronic device such as a cellular phone, elements that operate intermittently are arranged on a mounting substrate, and some of these elements generate heat rapidly when they start to operate. A temperature compensated piezoelectric oscillator (TCXO: Temperature Compensated Xtal Oscil)
lator) is arranged, the temperature detector that constitutes the temperature compensated piezoelectric oscillator outputs a voltage value that follows the rapid temperature change of the element. There is a problem that an irrelevant control voltage is generated and the oscillation frequency is affected.

In order to solve this problem, for example, in Patent Document 1, when the output of a temperature detector (temperature sensor) is inserted into an integration circuit (low-pass filter) and a thermal shock is applied, the difference voltage between the two is used, A method of performing frequency compensation for a rapid temperature change is described.

JP-A-5-145339 (FIG. 1)

However, the conventional method requires an integrating circuit consisting of a large-capacitance capacitor and resistor in order to cope with a rapid temperature change, and is not suitable for downsizing of an integrated circuit. There is a problem of being big. In addition, the effect of placing an element that generates heat in the vicinity cannot be avoided.

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 piezoelectric vibrator, and an oscillation circuit that controls an oscillation frequency of the piezoelectric vibrator based on a control voltage;
A first temperature detector that detects a temperature and outputs a first voltage; a second temperature detector that detects a temperature and outputs a second voltage; the first voltage and the second voltage; A difference circuit that outputs a third voltage that is a difference voltage, an adder circuit that outputs a fourth voltage that is the sum of the first voltage and the third voltage, and the fourth circuit And a control voltage generation circuit that generates the control voltage based on a voltage.

According to this configuration, when a heating element is disposed in the vicinity of the temperature compensated piezoelectric oscillator, the temperature difference between the first temperature detector close to the heating element and the second temperature detector far from the heating element is synthesized. Therefore, the frequency fluctuation due to the thermal shock from the heating element can be reduced.

[Application Example 2]
The temperature compensated piezoelectric oscillator according to the above, wherein the first temperature detector and the second temperature detector have substantially the same voltage-temperature characteristics.

According to this configuration, if the first temperature detector and the second temperature detector have the same voltage-temperature characteristics, even if there is no thermal shock, it is the same as the case where it is configured with one temperature detector. Detection results can be obtained.

[Application Example 3]
The temperature compensated piezoelectric oscillator according to the above, wherein the first temperature detector and the second temperature detector are arranged apart from each other.

According to this configuration, by arranging the first temperature detector and the second temperature detector apart from each other, the temperature when the thermal shock is received from the heating element and the temperature when the thermal shock is not received are Since the difference becomes large, the temperature difference can be easily detected.

The block diagram which shows the structure of the temperature compensation type | mold piezoelectric oscillator which concerns on 1st Embodiment. 1 is a circuit diagram showing a configuration of a temperature compensated piezoelectric oscillator according to a first embodiment. (A) Arrangement | positioning figure which shows the arrangement | positioning method on the board | substrate of the temperature compensation type | mold piezoelectric oscillator which concerns on 1st Embodiment, (B) The graph which shows the motion of the temperature sensor of the temperature compensation type | mold piezoelectric oscillator which concerns on 1st Embodiment. FIG. 6 is a configuration diagram showing a configuration of a temperature compensated piezoelectric oscillator according to Modification 1. FIG. 9 is a configuration diagram showing a configuration of a temperature compensated piezoelectric oscillator according to Modification 2. FIG. 6 is a layout diagram illustrating a method for arranging a temperature compensated piezoelectric oscillator according to a second modification. FIG. 9 is a configuration diagram showing a configuration of a temperature compensated piezoelectric oscillator according to Modification 3. FIG. 9 is a layout diagram illustrating a method for arranging a temperature compensated piezoelectric oscillator according to a third modification.

  Hereinafter, embodiments of a temperature compensated piezoelectric oscillator will be described with reference to the drawings.

(First embodiment)
<Configuration of temperature compensated piezoelectric oscillator>
First, the configuration of the temperature compensated piezoelectric oscillator according to the first embodiment will be described with reference to FIGS. FIG. 1 is a configuration diagram showing the configuration of the temperature compensated piezoelectric oscillator according to the first embodiment. FIG. 2 is a circuit diagram showing a configuration of the temperature compensated piezoelectric oscillator according to the first embodiment. FIG.
FIG. 6A is an arrangement diagram illustrating a method of arranging the temperature compensated piezoelectric oscillator according to the first embodiment on a substrate. FIG. 3B is a graph showing the movement of the temperature sensor of the temperature compensated piezoelectric oscillator according to the first embodiment.

As shown in FIG. 1, a temperature compensated piezoelectric oscillator 1 includes a piezoelectric vibrator 10, an oscillation circuit 150, a temperature sensor T1 that is a first temperature detector, and a temperature sensor T that is a second temperature detector.
2, difference circuit 120, adder circuit 130, control voltage generation circuit 140, EEPROM
(Electrically Erasable and Programmable Read Only Memory) 160. For simplification of the description in FIGS. 3 and 4, the difference circuit 120 and the adder circuit 130.
A circuit including the control voltage generation circuit 140 is referred to as a detection circuit 110.

The temperature sensor T1 outputs a voltage V1, which is a first voltage obtained by converting the detected temperature into a voltage. The temperature sensor T2 outputs a voltage V2, which is a second voltage obtained by converting the detected temperature into a voltage. The difference circuit 120 detects a difference between the voltage V1 and the voltage V2 and outputs a voltage V3 that is a third voltage. The adder circuit 130 detects the sum of the voltage V1 and the voltage V3 and outputs a voltage V4 that is a fourth voltage. The control voltage generation circuit 140 generates and outputs a control voltage VC based on the voltage V4. The oscillation circuit 150 is controlled so as to cancel the temperature characteristic of the oscillation frequency of the piezoelectric vibrator 10 by the control voltage VC, and outputs an oscillation signal from the output terminal OUT.

FIG. 2 shows specific circuit configurations of the temperature sensor T1, the temperature sensor T2, the difference circuit 120, and the adder circuit 130. The temperature sensor T1 has a resistor 112 between the power line and the ground line.
And two diodes 113 and 114 are connected in series. Resistor 112 and diode 1
The voltage V <b> 1 is output from the connection line with 13. In the temperature sensor T2, a resistor 116 and two diodes 117 and 118 are connected in series between a power supply line and a ground line. The voltage V2 is output from the connection line between the resistor 116 and the diode 117.

The differential circuit 120 includes a differential amplifier 122, a resistor R1, and a variable resistor R2. In the differential amplifier 122, the voltage V1 is applied to the + terminal, and the voltage V is applied to the − terminal via the resistor R1.
2 is applied, and the voltage V3 is output from the output terminal. The variable resistor R <b> 2 is connected between the − terminal and the output terminal of the differential amplifier 122, and the digital signal VR stored in the EEPROM 160.
The resistance value can be adjusted based on When a control signal is applied from the control terminal CS, the EEPROM 160 is written with data such as digital data for adjusting the variable resistor R2 from the data terminal DA.

The adding circuit 130 includes a differential amplifier 132 and resistors R3 and R4. In the differential amplifier 132, the voltage V1 is applied to the + terminal, the voltage V3 is applied to the − terminal via the resistor R3, and the voltage V4 is output from the output terminal. The resistor R4 is connected between the − terminal and the output terminal of the differential amplifier 132.

As shown in FIG. 3A, when the temperature compensated piezoelectric oscillator 1 and the heating element 20 are arranged on the substrate 300, the temperature sensor T1 is in the vicinity of the heating element 20, so that the heating element 20 is intermittently driven. When heat is generated, the temperature of the heating element 20 is affected. On the other hand, since the temperature sensor T2 is located away from the heating element 20, it is delayed to be affected by the temperature of the heating element 20.

As shown in FIG. 3B, when the heating element 20 is intermittently driven at time t1, the temperature sensor T
The voltage V1 output by 1 falls rapidly as the temperature rises. On the other hand, the voltage V2 output from the temperature sensor T2 falls more slowly than the voltage V1. A voltage obtained by synthesizing these voltages V1 and V2 (a voltage corresponding to V4 in FIG. 2) falls more slowly than the voltage V2.

  According to the present embodiment described above, the following effects can be obtained.

Since the conventional temperature-compensated piezoelectric oscillator has only one temperature sensor, the control voltage VC changes abruptly due to the influence of the heating element 20, but in this embodiment, the temperature sensor T1 close to the heating element 20 and the heat generation. Since the temperature difference of the temperature sensor T2 far from the element 20 can be synthesized, the frequency fluctuation due to the thermal shock from the heating element 20 can be reduced.

The embodiments of the temperature compensated piezoelectric oscillator have been described above. However, the embodiments are not limited to these embodiments, and can be implemented in various forms without departing from the scope of the invention. Hereinafter, a modification will be described.

(Modification 1) Modification 1 of the temperature compensated piezoelectric oscillator will be described. In the first embodiment, the case where the temperature sensor T1 and the temperature sensor T2 are disposed in the temperature compensated piezoelectric oscillator 1 has been described. However, the temperature sensor T2 may be disposed outside the temperature compensated piezoelectric oscillator 1. FIG. 4 is a configuration diagram showing the configuration of the temperature compensated piezoelectric oscillator according to the first modification.

As shown in FIG. 4, the temperature compensated piezoelectric oscillator 4 does not include the temperature sensor T2 and is disposed outside. In order to connect the temperature sensor T2 to the temperature compensated piezoelectric oscillator 4, no new terminal is provided, and the data terminal DA is also used. For this purpose, the temperature-compensated piezoelectric oscillator 4 includes a switch circuit 170. When the control signal input from the control terminal CS is enabled, the a terminal and the b terminal of the switch circuit 170 are connected, and the control signal is disabled. In this case, the switch circuit 170 operates so as to connect the terminals a and c. Therefore, EEPROM
During the period when data is written to 160, the control signal is enabled so that the temperature sensor T2 is disconnected. During the period when data is not written to the EEPROM 160, the control signal is disabled and the temperature sensor T2 is connected.

As shown in FIG. 4, by disposing the heating element 20, the temperature compensated piezoelectric oscillator 4 and the temperature sensor T2 on the substrate 400, the temperature sensor T2 becomes less susceptible to the temperature of the heating element 20.

(Modification 2) Modification 2 of the temperature compensated piezoelectric oscillator will be described. In the first embodiment, the method of arranging the two temperature sensors T1, T2 has been described. However, three or more temperature sensors may be arranged. FIG. 5 is a configuration diagram illustrating a configuration of a temperature compensated piezoelectric oscillator according to the second modification. FIG. 6 is an arrangement diagram illustrating a method of arranging the temperature compensated piezoelectric oscillator according to the second modification.

As shown in FIG. 5, the temperature compensated piezoelectric oscillator 5 includes a temperature sensor T1 and a temperature sensor T2.
In addition, a third temperature sensor T3 and a difference circuit 520 are further included. The temperature sensor T3 outputs a voltage V5 obtained by converting the detected temperature into a voltage. The difference circuit 520 detects a difference between the voltage V1 and the voltage V5 and outputs a voltage V6. The adder circuit 530
The sum of voltage V1, voltage V3 and voltage V6 is detected and voltage V4 is output. For simplification of the description in FIG. 6, the difference circuits 120 and 520, the adder circuit 530, and the control voltage generation circuit 140.
A circuit including the above is named a detection circuit 510.

As shown in FIG. 6A, by disposing the heating element 20 and the temperature compensated piezoelectric oscillator 5 on the substrate 600, the temperature sensor T3 is easily affected by the temperature of the heating element 20,
The temperature sensors T1, T2 are less susceptible to the temperature of the heating element 20. On the other hand, FIG.
As shown in FIG. 5, by arranging the heating element 20 and the temperature compensated piezoelectric oscillator 5 on the substrate 600, the temperature sensors T1 and T3 are easily affected by the temperature of the heating element 20, and the temperature sensor T2 generates heat. It becomes difficult to be influenced by the temperature of the element 20.

(Modification 3) Modification 3 of the temperature compensated piezoelectric oscillator will be described. In the modified example 2,
Although the method of arranging the three temperature sensors T1, T2, T3 and the two difference circuits 120, 520 has been described, a single difference circuit 120 can also be configured. FIG. 7 is a configuration diagram illustrating a configuration of a temperature compensated piezoelectric oscillator according to the third modification. FIG. 8 is an arrangement diagram illustrating a method of arranging the temperature compensated piezoelectric oscillator according to the third modification.

As shown in FIG. 7, the temperature-compensated piezoelectric oscillator 7 is configured to switch the voltages V2 and V5 output from the two temperature sensors T2 and T3 by the switch circuit 570 and input them to the difference circuit 120. The switch circuit 570 is a control signal V written in the EEPROM 160.
Based on S, whether the b terminal and the c terminal of the switch circuit 570 are connected or whether the a terminal and the c terminal are connected can be switched. For simplification of the description in FIG. 8, a circuit including the difference circuit 120, the adder circuit 130, the switch circuit 570, and the control voltage generation circuit 140 is named a detection circuit 710.

As shown in FIG. 8A, when the heating element 20 and the temperature compensated piezoelectric oscillator 7 are arranged on the substrate 800, the temperature sensors T1 and T3 are close to the heating element 20 and the temperature sensor T2 is moved from the heating element 20. Since it is far, the control signal VS is set so that the b terminal and the c terminal of the switch circuit 570 are connected. On the other hand, as shown in FIG. 8B, when the heating element 20 and the temperature compensated piezoelectric oscillator 7 are arranged on the substrate 800, the temperature sensors T1 and T2 are close to the heating element 20 and the temperature sensor T3 is the heating element. Since it is far from 20, the control signal VS is set so that the terminals a and c of the switch circuit 570 are connected.

DESCRIPTION OF SYMBOLS 1 ... Temperature compensated piezoelectric oscillator, 4 ... Temperature compensated piezoelectric oscillator, 5 ... Temperature compensated piezoelectric oscillator,
7 ... temperature compensated piezoelectric oscillator, 10 ... piezoelectric vibrator, 20 ... heating element, 110 ... detection circuit, 1
DESCRIPTION OF SYMBOLS 12 ... Resistance, 113, 114 ... Diode, 116 ... Resistance, 117, 118 ... Diode, 120 ... Differential circuit, 122 ... Differential amplifier, 130 ... Adder circuit, 132 ... Differential amplifier, 1
DESCRIPTION OF SYMBOLS 40 ... Control voltage generation circuit, 150 ... Oscillation circuit, 160 ... EEPROM, 170 ... Switch circuit, 300, 400 ... Substrate, 510 ... Detection circuit, 520 ... Difference circuit, 530 ... Adder circuit, 570 ... Switch circuit, 600 ... Substrate 710: Detection circuit, 800: Substrate.

Claims (3)

A piezoelectric vibrator;
An oscillation circuit for controlling the oscillation frequency of the piezoelectric vibrator based on a control voltage;
A first temperature detector for detecting temperature and outputting a first voltage;
A second temperature detector for detecting temperature and outputting a second voltage;
A difference circuit that outputs a third voltage that is a difference voltage between the first voltage and the second voltage;
An adder circuit that outputs a fourth voltage that is the sum of the first voltage and the third voltage;
A control voltage generation circuit for generating the control voltage based on the fourth voltage;
including,
A temperature compensated piezoelectric oscillator characterized by the above. 2. The temperature compensated piezoelectric oscillator according to claim 1, wherein the first temperature detector and the second temperature detector have substantially the same voltage-temperature characteristics. . 3. The temperature compensated piezoelectric oscillator according to claim 1, wherein the first temperature detector and the second temperature detector are arranged apart from each other.

Images