JP2002151957A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric oscillator that has functions exclusive to a temperature compensated crystal oscillator(TCXO) or a voltage controlled crystal oscillator(VCXO) so as to be downsized. SOLUTION: The piezoelectric oscillator including a piezoelectric vibrator, an oscillation use amplifier circuit, an oscillated frequency temperature compensation function circuit and an AFC(Automatic Frequency Control) function circuit is provided with a means for selecting either the oscillated frequency temperature compensation function or the AFC function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric oscillator using a piezoelectric element such as a quartz oscillator.

[0002]

2. Description of the Related Art A Colpitts type oscillation circuit is most commonly used for a crystal oscillator using a piezoelectric oscillator, particularly a crystal oscillator. Based on this Colpitts oscillation circuit,
Temperature Compensated Crystal Oscillator (TCX
O) or by adding a frequency variable element such as a variable capacitance diode to enable frequency adjustment and facilitate AFC (automatic frequency control) voltage controlled crystal oscillator (VCX
O) It is well known that various types of crystal oscillators have been produced in recent years due to performance or functional requirements of communication devices such as VCTCXO having both of them. .

[0003]

However, it is not preferable to prepare various types of crystal oscillators as a lineup according to the performance or function requirements of the customer, because this reduces production efficiency and is not preferable. Absent. It is also possible to increase the number of functions and reduce the lineup by incorporating various functions into one oscillator.However, when trying to consolidate functions into one oscillator to achieve multiple functions, the oscillator itself naturally becomes At present, there is a limit in a situation where there is a constraint that the size must be reduced and the size must be reduced.

The present invention has been made in view of the above circumstances, and a temperature-compensated oscillator (TCXO) is used as one oscillator.
Alternatively, it is another object of the present invention to provide a piezoelectric oscillator capable of consolidating the functions of a voltage controlled oscillator (VCXO) and achieving downsizing.

[0005]

In order to solve the above-mentioned object, a piezoelectric oscillator according to the present invention has the following features.
In a piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifier circuit, an oscillation frequency temperature compensation function circuit, and an AFC function circuit, the oscillation frequency temperature compensation function and AFC (automatic frequency control)
It is provided with a means for selecting one of the functions. The invention according to claim 2 of the piezoelectric oscillator according to the present invention,
In a piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifying circuit, an oscillation frequency temperature compensation function circuit and an AFC (automatic frequency control) function circuit, the oscillation frequency temperature compensation function circuit and the A
It is provided with means for operating both of the FC function circuits and means for selecting only one of the two.

According to a third aspect of the present invention, there is provided a piezoelectric oscillator according to the first or second aspect, wherein the means for realizing the oscillation frequency temperature compensation function circuit and the AFC function circuit have the same voltage variable capacitance. This is a device utilizing an element. According to a fourth aspect of the present invention, there is provided a piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifier circuit, an oscillation frequency temperature compensation function circuit, and an AFC (automatic frequency control) function circuit. , A voltage variable capacitance element is inserted in series, and the voltage variable capacitance element is connected to A through switching means.
One or both of the FC signal and the temperature compensation control signal are supplied at the same time. According to a fifth aspect of the present invention, there is provided a piezoelectric oscillator according to the first, second, third or fourth aspect, wherein the power supply to the oscillation frequency temperature compensation function circuit is cut off. The function is stopped.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments shown in the drawings. FIG. 1 is a circuit diagram of a piezoelectric oscillator according to an embodiment of the present invention. The oscillation amplifier circuit 1 includes a transistor and the like, and a crystal oscillator X and a resistor R1 are provided on the base of the transistor of the oscillation amplifier circuit 1. A switch 2 and a temperature compensating circuit 3 are connected in series, a variable capacitance diode D is connected between a connection point of the resistor R1 and the crystal oscillator and a ground, thereby forming a so-called indirect temperature compensation type Colpitts crystal oscillator. .

Here, the oscillation amplifier circuit 1 is connected via a terminal 4.
DC power is supplied to the collector of the transistor and the temperature compensation circuit 3, and the temperature compensation circuit 3 generates a temperature compensation voltage corresponding to the ambient temperature. Also,
The switch 2 is supplied with a frequency control voltage (AFC signal) and a switch switching signal via terminals 5 and 6, respectively, and the switch 2 selectively outputs the frequency control voltage and the temperature compensation voltage according to the switch switching signal. Resistance R1
Through the variable capacitance diode D. Further, the oscillation signal of the oscillator is supplied from the emitter of the transistor of the oscillation amplifier circuit 1 to the terminal 7 via the capacitor.
Is output to.

An operation example of the piezoelectric oscillator shown in FIG. 1 will be described below. First, the temperature compensating circuit 3 is a circuit configured by combining a plurality of resistors and thermistors in series or in parallel, and although not described in detail, generates a temperature compensating voltage according to the ambient temperature and supplies it to the switch 2. Has become. Therefore, when a voltage corresponding to, for example, the High level of the TTL signal is input to the terminal 6 as a switching signal, the switch 2 detects this and selectively outputs the temperature compensation voltage supplied from the temperature compensation circuit 3. The temperature compensation voltage is a resistor R1
To the cathode of the variable capacitance diode.

As described above, when the temperature compensation voltage is applied between the anode and the cathode of the variable capacitance diode D, and the temperature compensation voltage changes according to the ambient temperature, the equivalent capacitance between the anode and the cathode of the variable capacitance diode changes. Works like that. As a result, the change in the equivalent capacitance cancels the change in the oscillation frequency of the oscillation circuit based on the crystal oscillator due to the temperature, and the output frequency of the oscillator output from the terminal 7 is kept constant with respect to the temperature change. Therefore, the present piezoelectric oscillator can be operated as an indirect temperature compensated crystal oscillator.

On the other hand, when the switching signal supplied to the terminal 6 is set, for example, to the Low level voltage of the TTL signal, the switch 2 detects this and selectively outputs the control voltage supplied from the terminal 5. The control voltage is likewise supplied to the variable capacitance diode via the resistor R1. As a result, when the control voltage is changed, the equivalent capacitance between the anode and the cathode of the variable capacitance diode changes according to the change, and the oscillation frequency of the oscillation circuit changes. That is, the present piezoelectric oscillator can be used as a voltage-controlled crystal oscillator with the control voltage supplied to the terminal 5.

As described above, by switching the switch 2, the present piezoelectric oscillator can be selectively operated as either a temperature-compensated crystal oscillator or a voltage-controlled crystal oscillator. Since only the switch 2 is added and the number of parts is almost the same, it is easy to reduce the size. According to this configuration, the conventional TCXO and VC
XOs and XOs that have been commercialized separately are lined up as the same product, making it possible to handle both. Further, if desired, it can be mounted on a mobile phone or the like and switched to both to function.

In the embodiment shown in FIG. 1 as described above, the switch 2 is provided. However, the embodiment of the present invention is not limited to this. For example, as shown in FIG. 2 may not be provided. FIG. 2 is a circuit diagram showing a second embodiment of the piezoelectric oscillator according to the present invention. In FIG. 2, the output voltage of the temperature compensating circuit 3 is applied to the cathode of the variable capacitance diode D via a resistor R2.
Can be supplied with a control voltage from the terminal 5 via the resistor R3.

On the other hand, since the power supply can be supplied to the temperature compensation circuit 3 through the dedicated terminal 8, when the present piezoelectric oscillator is operated as a temperature-compensated crystal oscillator, it is mounted on a substrate on which the present piezoelectric oscillator is mounted. A power supply is connected to the terminal 8, or the terminal 8 is connected to the terminal 4. At this time,
The terminal 5 may be left open. When operating this piezoelectric oscillator as a voltage controlled crystal oscillator,
The terminal 8 is left open. In this case, no power is supplied to the temperature compensating circuit 3, the temperature compensating voltage is cut off, and the cathode of the variable capacitance diode D and the temperature compensating circuit 3 are separated by the resistor R2 (high resistance). An operation equivalent to the switching by the switch described in the embodiment shown in FIG. 1 can be performed. Furthermore,
According to this configuration, both TCXO and VCXO (VCTC
It would be easy to function as XO).

The embodiment shown in FIG. 2 has a configuration in which the number of resistors is increased by one compared with that of FIG. 1 but no switch is provided, so that it is possible to further reduce the size of the embodiment shown in FIG. There are advantages. In the past, one piezoelectric oscillator that had only one function was integrated in this way, and product integration would be improved, and production efficiency would be improved, and it was also effective in responding to versatile use at customers It is.

[0016]

As described above, the present invention relates to a piezoelectric oscillator comprising an oscillation circuit, a piezoelectric vibrator, a variable capacitance diode, and an oscillation frequency temperature compensation circuit, wherein a frequency control terminal is added to the piezoelectric oscillator. Since it is possible to select whether to supply the voltage supplied to the variable capacitance diode from the oscillation frequency temperature compensation circuit or the frequency control terminal, it is possible to selectively use the temperature compensation piezoelectric oscillator or the voltage controlled crystal oscillator. This is very effective in providing a piezoelectric oscillator that can be used.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a piezoelectric oscillator according to the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the piezoelectric oscillator according to the present invention.

[Description of Signs] 1 ... Amplification circuit for oscillation 2 ... Switch 3 ... Temperature compensation circuit 4,5,6,7,8 ... Terminal R1, R2, R3 ... Resistance D ...・ Variable capacitance diode X: Crystal oscillator

Claims (5)

[Claims] 1. A piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifier circuit, an oscillation frequency temperature compensation function circuit, and an AFC (automatic frequency control) function circuit, wherein the oscillation frequency temperature compensation function and the AFC (automatic frequency control) function are provided. A means for selecting either one of the above. 2. A piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifier circuit, an oscillation frequency temperature compensation function circuit, and an AFC (automatic frequency control) function circuit, wherein both the oscillation frequency temperature compensation function circuit and the AFC function circuit are provided. A piezoelectric oscillator comprising: means for functioning; and means for selecting only one of the two. 3. An oscillation frequency temperature compensation function circuit and an AFC
3. The piezoelectric oscillator according to claim 1, wherein the means for realizing the functional circuit uses the same voltage variable capacitance element. 4. A piezoelectric oscillator including a piezoelectric vibrator, an oscillation amplifier circuit, an oscillation frequency temperature compensation function circuit, and an AFC (automatic frequency control) function circuit, wherein a voltage variable capacitance element is inserted in series with the piezoelectric vibrator. ,
A piezoelectric oscillator characterized in that one or both of an AFC signal and a temperature compensation control signal are supplied to the voltage variable capacitance element via switching means at the same time. 5. The apparatus according to claim 1, wherein the power supply to the oscillation frequency temperature compensation function circuit is cut off to stop the function.
Or the piezoelectric oscillator according to claim 4.