JP2001016037A - Piezoelectric oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a miniaturized piezoelectric oscillator which can have its output oscillation frequency adjusted accurately, without the need for installing special components. SOLUTION: This piezoelectric oscillator 1 is equipped with a piezoelectric oscillating element 5, a package 11 which stores the piezoelectric oscillating element 5 and has stray capacitance, a frequency adjusting means (having stray capacitance electrode) 17 which adjusts a oscillation frequency fout by making use of the stray capacitance of the package 11, so as to provide a frequency control means VC which controls the oscillation frequency fout according to an applied voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a piezoelectric oscillator capable of controlling an oscillation frequency.

[0002]

2. Description of the Related Art FIG. 11 is a perspective view showing an example of the appearance of a conventional piezoelectric oscillator 101.

The piezoelectric oscillator 101 is, for example, a voltage-controlled crystal oscillator (VCXO) whose output oscillation frequency changes according to an external input voltage. Piezoelectric oscillator 101
Consists of a box-shaped package 111 in appearance, and has an oscillation circuit 139 therein. The oscillation circuit 139 will be described later. The package 111 is made of, for example, ceramics, and is formed by stacking a base 22 and a surface 11.
It has a lid (not shown) provided on the d side. The piezoelectric oscillator 101 is provided with a ground electrode GND, a control voltage terminal 37, a power supply terminal 35, and an output terminal 33, for example, on the back surface 11a of the package 111.

A ground electrode GND, a control voltage terminal 37, a power supply terminal 35, and an output terminal 33 are connected to an oscillation circuit 139, respectively.
(Hereinafter, simply referred to as “terminals”), and are provided at substantially four corners on the back surface 11 a of the package 111.

The ground electrode GND is used to ground the piezoelectric oscillator 101, and is set to, for example, 0 [V]. The output terminal 33 is an output terminal of the oscillation frequency output by the oscillation circuit 139. Control voltage terminal 37
Is a terminal for controlling the oscillation frequency output from the output terminal 33 according to the input voltage. Power supply terminal 35
FIG. 12 shows the power supply voltage of the oscillation circuit 139 as shown in FIG.
Is an input terminal for inputting the power supply voltage Vcc to the piezoelectric oscillator 101.

FIG. 12 is a circuit diagram showing an example of the oscillation circuit 139 of FIG.

In the following description, when it is assumed that each element is grounded, each element is connected to the ground electrode G of FIG.
ND is connected.

The oscillation circuit 139 includes, for example, a first resistor R1
To a sixth resistor R6, a first capacitor C1, a second capacitor C2, a first transistor TR1, a second transistor TR2, a constant voltage power supply Vreg, a piezoelectric vibrating element 5, and a variable capacitor VC. In the following description, “variable capacitor” is abbreviated to “varicap”.

The constant voltage power supply Vreg has, for example, a negative electrode grounded and a positive electrode connected to the third resistor R3.
The constant voltage power supply Vreg is obtained by regulating the power supply voltage Vcc input from the power supply terminal 35 by a predetermined stabilizing circuit (not shown) to make the voltage constant. The third resistor R3 is connected to the base of the first transistor TR1 and the fourth resistor R3.
And the first transistor TR
1 to the base. First transistor TR1
Has an emitter connected to the collector of the second transistor TR2, a base connected as described above, and a collector connected to the first resistor R1 and the output terminal 33 as described later.

The control voltage terminal 37 is connected to a sixth resistor R6. The control voltage terminal 37 is a terminal for inputting the above-described input voltage for controlling the oscillation frequency of the oscillation circuit 139. The sixth resistor R6 is connected to the piezoelectric vibrating element 5
And one end thereof is connected to a grounded varicap VC. The varicap VC is, for example, a capacitor provided in the oscillation circuit 139 for controlling the oscillation frequency fout output from the oscillation circuit 139. Piezoelectric vibration element 5
Is connected to a fourth resistor R4, a fifth resistor R5 having one end grounded, one end of the first capacitor C1, and a base of the second transistor TR2. The other end of the first capacitor C1 is connected to a second capacitor C2 having one end grounded, a second resistor R2 having one end grounded, and an emitter of the second transistor TR2.

The power terminal 35 is also connected to the first resistor R1. The power supply terminal 35 is a terminal for supplying a power supply voltage Vcc to the oscillation circuit 139. First resistor R1
Is connected to the output terminal 33 and the emitter of the first transistor TR1.

In the conventional piezoelectric oscillator 101, for controlling the oscillation frequency fout output from the output terminal 33, for example, a passive component such as the above-described varicap VC has been used. The varicap VC is also called a variable capacitance diode. When a reverse voltage is applied to both ends of the diode, the capacitance between the electrodes changes according to the voltage.
Therefore, in the piezoelectric oscillator 101, by providing the varicap VC in the oscillation circuit 139, the oscillation frequency can be controlled by the applied voltage. With such a configuration, the piezoelectric oscillator 101 adjusts the oscillation frequency fout output from the output terminal 33.

However, unexpected stray capacitance usually occurs in the package 11 of the piezoelectric oscillator 101 due to wiring and the like constituting the oscillation circuit 139. Therefore, in the piezoelectric oscillator 101, even if the varicap VC is provided in the oscillation circuit 139, the oscillation frequency fout output from the output terminal 33 may not be a desired value for a predetermined applied voltage.

In such a case, a first method for adjusting the oscillation frequency fout output from the piezoelectric oscillator 101 is as follows.

The oscillation circuit 139 includes a third capacitor C3 called a chip capacitor having a fixed value and a fourth capacitor C3.
Are provided in parallel with, for example, the varicap VC as shown in FIG. 13 or in series with the varicap VC as shown in FIG. That is, in each piezoelectric oscillator 101, the chip capacitor is provided in the vicinity of the varicap VC so that the oscillation frequency fout from the output terminal 33 becomes exactly a desired value for a predetermined applied voltage.

As a second method of adjusting the oscillation frequency fout output from the piezoelectric oscillator 101, there has been a method using a trimming capacitor. The trimming capacitor is a variable capacitor provided in place of the chip capacitor having a fixed capacitance as described above. The capacitance of the trimming capacitor can be adjusted by trimming a part of the electrode constituting the capacitor to reduce the area.

As an example of a trimming capacitor, a trimming component 125 provided on the surface 11d of the piezoelectric oscillator 101 as shown in FIG. 15 or a surface 11d of the piezoelectric oscillator 101 and the laminated surface 111a shown in FIG. There is a trimming electrode 126 provided.

The trimming part 125 shown in FIG.
As described above, a part of the electrode 125a is trimmed by a laser, for example, and the area of the electrode 125a is changed to adjust the capacitance. On the other hand, the trimming electrodes of FIG. 17 are stacked as shown in FIG.
24 is trimmed, so that the trimming electrode 126 is trimmed.
Was adjusted.

Thus, the output oscillation frequency of the piezoelectric oscillator 101 provided with the trimming capacitor could be adjusted.

As a third method of adjusting the oscillation frequency fout output from the piezoelectric oscillator 101, the static area is increased by increasing the area of an electrode constituting a predetermined adjusting capacitor, contrary to the above-described trimming capacitor. This is a method of adjusting the capacitance. Specifically, for example, package 1
This is realized by connecting the divided adjustment capacitors, which are stacked on the surface of the capacitor 11 or provided on the surface thereof, by wire bonding or the like. Therefore, the piezoelectric oscillator 101 provided with the adjusting capacitor outputs the oscillation frequency f
out could be set to a desired frequency for a predetermined applied voltage.

[0021]

However, the varicap VC has a problem that the capacitance characteristics of the varicap VC vary widely between products.

FIG. 19 is a diagram showing an example of a variation characteristic of the capacitance of the varicap VC.

In FIG. 19, the vertical axis indicates the capacity of the varicap VC, and A to G in the figure indicate the categories of the variations. On the other hand, the horizontal axis indicates the number n of the varicaps VC in each capacity. Referring to FIG. 19, although many varicaps are in the vicinity of the section D, some varicaps belong to the section A and the section G, and their electric characteristics vary.

Therefore, in the first method described above, the characteristics are measured for each of the varicaps VC having different characteristics, and chip capacitors selected based on the measured values must be provided in the piezoelectric oscillator 101. did not become. In addition, when the first method is applied to provide the chip capacitors classified according to the capacitance in each section to the piezoelectric oscillator 101 in accordance with the capacitance characteristics of the varicap VC, it is extremely troublesome. It was hanging.

FIG. 20 is a diagram showing an example of a variation characteristic of the capacitance of the varicap VC.

FIG. 20 shows "control voltage Vco [V] -oscillation frequency f (fout) characteristics". Specifically, the vertical axis represents the oscillation frequency f (fou) output from the output terminal 33.
t) indicates the amount of change Δf / f [ppm], and the horizontal axis is shown in FIG.
Control voltage Vco input from the control voltage terminal 37
[V] is shown. Therefore, FIG. 20 shows a deviation of the oscillation frequency fout from the voltage Vco of the control voltage terminal 37. FIG. 20 shows two predetermined standard lines. Whether or not the characteristics of the capacitance of the varicap VC is within the standard is determined by “control voltage Vco [V] −oscillation frequency f
(Fout) characteristic ”can be determined based on whether or not it falls between two predetermined standard lines.

Conventionally, chip capacitors are classified according to the varicap VC and provided in the oscillation circuit 139 by applying the first method in consideration of the variation characteristics of the capacitance of the varicap VC as shown in FIG. Attempting to do so was very time-consuming.

In the second method and the third method, the trimming component 125 shown in FIG. 15 and the trimming electrode 126 shown in FIG. 17 may change with time, and their electrical characteristics may change. Further, as shown in FIG. 18, the package 11 formed by stacking
When the trimming electrode 126 is provided between the laminations, not only does the thickness increase, but also the trimming electrode 1
26, etc. had to be electrically connected to other parts. For this reason, the piezoelectric oscillator 101
1 was too thick and could not be miniaturized.

An object of the present invention is to solve the above-mentioned problems and to provide a piezoelectric oscillator capable of accurately adjusting an output oscillation frequency without providing special components and achieving downsizing. It is.

[0030]

According to a first aspect of the present invention, there is provided a piezoelectric vibrating element, a package accommodating the piezoelectric vibrating element and having a stray capacitance, and an oscillation frequency utilizing the stray capacitance of the package. It is characterized by comprising frequency adjusting means for adjusting, and frequency controlling means for controlling the oscillation frequency according to an applied voltage.

According to the structure of the first aspect, the package houses the piezoelectric vibrating element and has a floating capacitance in advance. The oscillation frequency of the piezoelectric vibration element is affected by the stray capacitance of the package. In this piezoelectric oscillator,
Frequency adjusting means adjusts the oscillation frequency using the stray capacitance generated in the package. Therefore, the piezoelectric oscillator can accurately adjust the oscillation frequency without providing any special parts. Further, the piezoelectric oscillator does not need to be provided with any special parts, so that the size can be reduced.

According to a second aspect of the present invention, in the configuration of the first aspect, the frequency adjusting means is an electrode provided on the package, and adjusts the stray capacitance by changing an area of the electrode. And

According to the configuration of the second aspect, the frequency adjusting means can change the stray capacitance generated in the package by changing the area of the electrode provided on the package. Since the oscillation frequency is affected by the stray capacitance generated in the package, by appropriately adjusting the stray capacitance, the piezoelectric oscillator can accurately adjust the output oscillation frequency.

According to a third aspect of the present invention, in the configuration of the second aspect, the package is provided with a shield layer surrounding at least a part of the frequency adjusting means.

According to the configuration of the third aspect, the piezoelectric oscillator can prevent the noise generated by the piezoelectric vibrating element from leaking to the outside and can prevent the influence of the noise from the outside.

According to a fourth aspect of the present invention, in the configuration of the second or third aspect, the frequency adjusting means is for connecting a plurality of electrodes and the plurality of electrodes, and A connection portion exposed to the outside.

According to the configuration of the fourth aspect, when adjusting the oscillation frequency, the frequency adjusting means changes the area of the electrodes constituting the frequency adjusting means by disconnecting the connecting portion connecting the plurality of electrodes. You. Thereby, the frequency adjusting means can adjust the stray capacitance generated in the package. Therefore, the piezoelectric oscillator can accurately adjust the oscillation frequency.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the frequency adjusting means is a part of a wiring of an electronic circuit including the piezoelectric vibrating element.

According to this configuration, the frequency adjusting means is a part of the wiring. Therefore, the frequency adjusting means is a part of the wiring, and the piezoelectric oscillator does not need to be provided with the frequency adjusting means as a special component, so that the size can be reduced.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the frequency adjustment means is provided between the piezoelectric vibration element and the frequency control means.

According to the configuration of claim 6, the frequency adjusting means is constituted by wiring between the piezoelectric vibrating element and the frequency control means. Therefore, when the area of the electrode of the frequency adjusting means is changed, the capacitance changes, and the oscillation frequency is effectively affected, but portions other than the piezoelectric vibration element are not affected.

According to a seventh aspect of the present invention, in any one of the second to sixth aspects, the frequency adjusting means is a single pole.

According to the configuration of the seventh aspect, the frequency adjusting means does not particularly have the paired electrodes. Therefore, the size of the piezoelectric oscillator is reduced.

According to an eighth aspect of the invention, in any one of the first to seventh aspects, the frequency control means has a varicap.

According to the eighth aspect of the present invention, since the piezoelectric oscillator has the frequency adjusting means, the oscillation frequency can be accurately adjusted for a predetermined applied voltage even if a varicap having characteristic variations is used for the frequency control means. To a desired value.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

In the following description, the term “floating capacitance” refers to a capacitance generated in a package of an electronic component, for example, between wirings of the electronic component. In the following description, "electronic components"
Are simply referred to as “parts”.

First Embodiment FIG. 1 is a perspective view showing an example of the appearance of a piezoelectric oscillator 1 according to a first embodiment of the present invention.

The piezoelectric oscillator 1 is, for example, a voltage-controlled crystal oscillator (VCXO) whose output oscillation frequency changes according to an external input voltage. The piezoelectric oscillator 1 is a box-shaped package 11 in appearance, and has an oscillation circuit 39 inside. The oscillation circuit 39 will be described later.
The package 11 has a base 22 made of, for example, ceramics and laminated, and a lid (not shown) provided on the surface 11d side. The piezoelectric oscillator 1 is provided with a ground electrode GND, a control voltage terminal 37, a power supply terminal 35, and an output terminal 33, for example, on the back surface 11a of the package 11.

The ground electrode GND, the control voltage terminal 37, the power supply terminal 35, and the output terminal 33 are electrode terminals (hereinafter simply referred to as "terminals") of the oscillation circuit 39, and are provided at substantially four corners on the back surface 11a of the package 11. Have been. Ground electrode GND, control voltage terminal 37, power supply terminal 35
The output terminal 33 is electrically connected to a predetermined portion of the oscillation circuit 39.

The ground electrode GND is for grounding the piezoelectric oscillator 1, and is set to, for example, 0 [V]. The output terminal 33 is an output terminal of the oscillation frequency output by the oscillation circuit 39. The control voltage terminal 37 is a terminal for controlling the oscillation frequency output from the output terminal 33 by adjusting the input voltage (applied voltage).
The power supply terminal 35 is an input terminal for inputting a power supply voltage Vcc of FIG. 4 described later as a power supply voltage of the oscillation circuit 39 to the piezoelectric oscillator 1.

FIG. 2 shows the back surface 11a of the piezoelectric oscillator 1 shown in FIG.
It is a top view showing the example of composition of.

The piezoelectric oscillator 1 is provided with, for example, a stray capacitance adjusting electrode 17 (frequency adjusting means) on the back surface 11a. The floating capacitance adjusting electrode 17 includes, for example, terminals 33 and 35 provided at four corners on the back surface 11 a of the piezoelectric oscillator 1.
37 and in a region surrounded by GND. The stray capacitance adjusting electrode 17 is, for example, at least one electrode, preferably a first electrode 17a as a plurality of electrodes.
(Frequency adjusting means), the second electrode 17b (frequency adjusting means) and the third electrode 17c (frequency adjusting means),
At least one trimming unit 21 (frequency adjusting means, for connecting these electrodes 17a to 17c, respectively)
Connection part).

Each of the first electrode 17a, the second electrode 17b, and the third electrode 17c is, for example, a plate-like electrode, and is provided on the back surface 11a so as not to overlap with each other.

Each of these trimming sections 21 can be trimmed by, for example, a laser beam. When the trimming portion 21 is trimmed, the floating capacitor adjusting electrode 17 has a reduced electrode area, and thus the package 11
Is changed. The trimming unit 21 is provided with a terminal 31. The terminal 31 is connected to a piezoelectric vibrating element 5, a sixth resistor R6, and a varicap VC described later with reference to FIG.

The stray capacitance adjusting electrode 17 affects the oscillation frequency but is preferably connected to a wiring which does not affect the operation of the other elements. A specific arrangement example will be described later.

FIG. 3 is a sectional view showing an example of a section taken along line AA ′ of the piezoelectric oscillator 1 of FIG.

The piezoelectric oscillator 1 is generally a package 1
1. Piezoelectric vibration element 5, IC (Integrated C)
ircuit) 3 and the like.

The package 11 includes a laminated base 22
And a lid 15.

When the base 22 is laminated, a concave portion is formed therein. At the bottom of the concave portion, for example, an IC 3 connected to a predetermined terminal of the base 22 by a wire or the like is provided. The upper portion of the IC 3 is covered with the piezoelectric vibrating element 5, and one end of the piezoelectric vibrating element 5 is electrically connected and fixed to the connection electrode 27 using, for example, a conductive adhesive. The lid 15 is fixed to the base 22 so as to seal the piezoelectric vibrating element 5, the IC 3, and the like. Therefore, the piezoelectric vibrating element 5 and the like
It will be located inside. The base 22 is made of a ceramic material such as alumina. The lid 15 is
For example, metal such as Kovar or 42 alloy having a coefficient of linear expansion close to that of ceramic such as alumina or ceramic such as alumina is used.

The piezoelectric vibrating element 5 is, for example, a vibrating element made of quartz. The piezoelectric vibration element 5 vibrates at a predetermined frequency (oscillation frequency) by the applied driving voltage.

The stray capacitance adjusting electrode 17 is connected to the connection electrode 27, for example, a coating 19 made of an insulating material.
Almost covered by. Therefore, the floating capacitance adjusting electrode 17 is insulated from the outside. However, the coating 19 is not provided near the trimming portion 21 of the stray capacitance adjusting electrode 17. This is to make it easier to trim the trimming portion 21 with laser light when changing the electrode area of the stray capacitance adjusting electrode 17 as described later.

FIG. 4 is a circuit diagram showing an example of the oscillation circuit 39 of FIG.

In the following description, when each element is grounded, each element is connected to the ground electrode GN of FIG.
D is connected.

The oscillation circuit 39 includes, for example, first resistors R1 to R1.
Sixth resistor R6, first capacitor C1, second capacitor C2, fifth capacitor C5, first transistor TR1, second transistor TR2, constant voltage power supply Vre
g, a piezoelectric vibrating element 5 and a varicap VC.

The constant voltage power supply Vreg has, for example, a negative electrode grounded and a positive electrode connected to the third resistor R3.
The constant voltage power supply Vreg is obtained by regulating the power supply voltage Vcc input from the power supply terminal 35 by a predetermined stabilizing circuit (not shown) to make the voltage constant. The third resistor R3 is connected to the fifth capacitor C5, the base of the first transistor TR1, and the fourth resistor R4,
A voltage is applied to the base of the first transistor TR1. The first transistor TR1 has an emitter connected to the collector of the second transistor TR2, a base connected as described above, and a collector connected to the first resistor R1 and the output terminal 33 as described later. Have been.

The control voltage terminal 37 is connected to the sixth resistor R6. The control voltage terminal 37 is a terminal for inputting the above-described input voltage for controlling the oscillation frequency of the oscillation circuit 39. The sixth resistor R6 is connected to the piezoelectric vibrating element 5 and a varicap VC whose one end is grounded. The varicap VC has, for example, an oscillation frequency fout
Is a capacitor provided in the oscillation circuit 39 for controlling the power supply. The piezoelectric vibration element 5 is connected to the fourth resistor R4, a fifth resistor R5 having one end grounded, one end of the first capacitor C1, and the base of the second transistor TR2. The other end of the first capacitor C1 is connected to a second capacitor C2 having one end grounded, a second resistor R2 having one end grounded, and an emitter of the second transistor TR2.

The power supply terminal 35 is also connected to the first resistor R1. The power supply terminal 35 is a terminal for supplying a power supply voltage Vcc to the oscillation circuit 39. First resistor R1
Is connected to the output terminal 33 and the collector of the first transistor TR1.

A feature of the piezoelectric oscillator 1 is that the stray capacitance adjusting electrode 17 is connected to, for example, the sixth resistor R6, the piezoelectric vibrating element 5, and the varicap VC (frequency control means).

The electrodes constituting the stray capacitance adjusting electrode 17 are as follows.
For example, it is constituted by a part of the wiring between the piezoelectric vibration element 5 and the varicap VC. Therefore, the stray capacitance adjusting electrode 17
Is a part of the wiring of the oscillation circuit 39, so that the piezoelectric oscillator 1 does not need to be provided with special components, and can be downsized.

Therefore, the stray capacitance adjusting electrode 17 is provided, for example, between the piezoelectric vibrating element 5 and the varicap VC. With such a configuration, the stray capacitance adjusting electrode 17 effectively affects the oscillation frequency fout in the oscillation circuit 39, but does not affect the operation of other components and the like. be able to.

Here, the electrode constituting the stray capacitance adjusting electrode 17 is, for example, a single electrode having no paired electrode. Therefore, the stray capacitance adjusting electrode 17 does not need to have a paired electrode, so that the piezoelectric oscillator 1 does not need to be provided with special components, and can be downsized.

The procedure for adjusting the oscillation frequency fout output from the piezoelectric vibrating element 5 by the piezoelectric oscillator 1 will now be described with reference to FIGS.

FIG. 5 is a diagram showing an example of an adjustment system 41 for adjusting the oscillation frequency fout output from the piezoelectric oscillator 1 of FIG.

FIG. 6 is a perspective view showing a state of the piezoelectric oscillator 1 whose oscillation frequency fout is adjusted by the adjustment system 41 of FIG.

The adjustment system 41 generally includes the computer 30 and the interface device 43.

The computer 30 is connected to the interface device 43 via the signal line 29. The computer 30 is for controlling the interface device 43. The interface device 43 controls the laser device 49 of FIG. The interface device 43 is connected to the laser device 49 of FIG. 6 by, for example, a laser device control line 45, the output signal line 46 is connected to the output terminal 33 of FIG. 6, and the control voltage signal line 47 is connected to the output terminal 33 of FIG. Is connected to the control voltage terminal 37 of

In the piezoelectric oscillator 1, for example, a ground terminal GND is grounded, and a power supply voltage Vcc is supplied to a power supply terminal 35.

The computer 30 controls the interface device 43 to input a control voltage Vco of a predetermined voltage to the control voltage terminal 37 via the control signal line 47. The piezoelectric oscillator 1 outputs an oscillation frequency fout as an output preset for such a control voltage Vco to an output terminal 33.
Output to The package 11 has a stray capacitance due to, for example, the wiring of the built-in oscillation circuit 39. Since the value of the stray capacitance cannot be predicted when the piezoelectric oscillator 1 is designed, the oscillation frequency fout output to the output terminal 33 is slightly different from a desired value when the piezoelectric oscillator 1 is designed.

Here, the computer 30 is, for example, shown in FIG.
Is controlled, and the trimming section 21 is trimmed by the laser device 49 in accordance with the error. The stray capacitance adjusting electrode 17 is trimmed, for example, at a predetermined trimming portion 21 and, for example, at least one of the electrodes 17a to 17c is cut off. The stray capacitance generated in the package 11 is changed by reducing the electrode area of the stray capacitance adjusting electrode 17. Since the stray capacitance adjusting electrode 17 is directly connected to the piezoelectric vibration element 5 as shown in FIG. 4, it affects the oscillation frequency fout.

In this state, the computer 30 measures the oscillation frequency fout output from the output terminal 33. When the piezoelectric oscillator 1 outputs the desired oscillation frequency fout, the adjustment system 41 ends the adjustment.

Therefore, the piezoelectric oscillator 1 can output the oscillation frequency fout in accordance with the characteristics of the varicap VC without providing special components such as a conventionally used chip capacitor for adjustment in the oscillation circuit 39. Can be adjusted accurately.

Second Embodiment FIG. 7 shows a piezoelectric oscillator 1a according to a second embodiment of the present invention.
It is a perspective view which shows an example of the external appearance of. FIG. 8 is a plan view showing an example when the piezoelectric oscillator 1a of FIG. 7 is viewed from the back surface 11a side. FIG. 9 is a sectional view showing an example of the piezoelectric oscillator 1a of FIG. 7 when viewed from the side.

The piezoelectric oscillator 1a according to the second embodiment of the present invention has substantially the same configuration as that of the piezoelectric oscillator 1 according to the first embodiment in FIGS. explain.

The piezoelectric oscillator 1a has an outer surface 11
a is provided with at least one trimming unit 21a (frequency adjusting means, connection unit). Trimming unit 21a
For example, as shown in FIG. 8, the electrode 17d, the electrode 17e, the electrode 17g, and the electrode 17h are connected to each other, and for example, as shown in FIG. The trimming portion 21a is provided with the electrodes 17d, 17e, 17g, and 17h serving as the stray capacitance adjusting electrodes 17f built in the package 11,
The connection is made via predetermined wiring extending from the trimming portion 21a. The trimming portion 21a is exposed outside the package 11, for example, as shown in FIG.

When the oscillation frequency fout of the piezoelectric oscillator 1a is adjusted, at least one trimming section 21a is trimmed by the adjustment system 41 if necessary. Thereby, the stray capacitance generated in the package 11 of the piezoelectric oscillator 1a is changed, and the oscillation frequency fout output from the piezoelectric oscillator 1a is adjusted.

According to such a configuration, the piezoelectric oscillator 1a
In addition to the effects of the first embodiment, the stray capacitance adjusting electrode 17f is not exposed to the outside, so that the first embodiment does not require the required insulating coating.

Third Embodiment FIG. 10 shows a piezoelectric oscillator 1 according to a third embodiment of the present invention.
It is sectional drawing which shows an example of the cross section when b is seen from a side surface.

The piezoelectric oscillator 1b according to the third embodiment of the present invention is substantially the same as the piezoelectric oscillator 1 according to the first embodiment in FIGS. 1 to 6 and the piezoelectric oscillator 1a according to the second embodiment in FIGS. Since the configuration is the same and the adjustment methods are almost the same, only different points will be described.

The characteristic features of the piezoelectric oscillator 1b are as follows.
The second embodiment is that a shield layer 23 is provided on a base 22 of the piezoelectric oscillator 1a according to the second embodiment. The shield layer 23 is preferably provided in the package 11 having the base 22 so as to surround at least a part of the stray capacitance adjusting electrode 17f, for example.

According to such a configuration, the piezoelectric oscillator 1b
In addition to the effects of the second embodiment, it is possible to prevent the noise generated by the piezoelectric vibrating element 5 from leaking to the outside of the package 11 and to prevent the influence of external noise.

The present invention is not limited to the above embodiment,
Various changes can be made without departing from the scope of the claims.

In the above description, the piezoelectric oscillators 1, 1a and 1b are, for example, stray capacitance adjusting electrodes 17, 17f, respectively.
Capacitance adjusting electrode 1 by reducing the area of the electrode constituting
7, the oscillation frequency fout from the output terminal 33 is adjusted. On the other hand, the piezoelectric oscillator has an area of the floating capacitance adjustment electrode by connecting the divided electrodes of the floating capacitance adjustment electrode having, for example, divided electrodes by wire bonding, solder, conductive adhesive, or the like. And output oscillation frequency fou
A form in which t is adjusted may be used.

[0094]

According to the present invention, the output oscillation frequency can be accurately adjusted without special components, and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of the appearance of a piezoelectric oscillator according to a first embodiment of the present invention.

FIG. 2 is a plan view showing a configuration example of the back surface of the piezoelectric oscillator of FIG. 1;

FIG. 3 is a sectional view showing an example of the AA ′ section of the piezoelectric oscillator 1 of FIG. 2;

FIG. 4 is a circuit diagram illustrating an example of the oscillation circuit of FIG. 1;

FIG. 5 is a diagram showing an example of an adjustment system for adjusting the oscillation frequency output from the piezoelectric oscillator of FIG.

FIG. 6 is a perspective view showing a state of a piezoelectric oscillator whose oscillation frequency is adjusted by the adjustment system of FIG. 5;

FIG. 7 is a perspective view showing an example of the appearance of a piezoelectric oscillator according to a second embodiment of the invention.

FIG. 8 is a plan view showing an example when the piezoelectric oscillator of FIG. 7 is viewed from the back side.

9 is a cross-sectional view illustrating an example of the piezoelectric oscillator of FIG. 7 when viewed from a side.

FIG. 10 is a cross-sectional view showing an example of a cross section when a piezoelectric oscillator according to a third embodiment of the present invention is viewed from a side.

FIG. 11 is a perspective view showing an example of the appearance of a conventional piezoelectric oscillator.

FIG. 12 is a circuit diagram illustrating an example of the oscillation circuit of FIG. 11;

FIG. 13 is a circuit diagram illustrating an example of the oscillation circuit of FIG. 11;

FIG. 14 is a circuit diagram illustrating an example of the oscillation circuit of FIG. 11;

FIG. 15 is a perspective view showing an example of the appearance of a conventional piezoelectric oscillator.

16 is a sectional view showing an example of a partial section of the piezoelectric oscillator shown in FIG. 15;

FIG. 17 is a perspective view showing an example of the appearance of a conventional piezoelectric oscillator.

FIG. 18 is a sectional view showing an example of a partial section of the piezoelectric oscillator shown in FIG. 17;

FIG. 19 is a diagram showing an example of variation in capacitance of a varicap.

FIG. 20 is a diagram showing that “control voltage Vco [V] -oscillation frequency f (fout) characteristic” varies due to variation in the capacitance of the varicap.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric oscillator 1a Piezoelectric oscillator 1b Piezoelectric oscillator 5 Piezoelectric vibrating element 11 Package 17 Floating capacitance adjustment electrode (frequency adjustment means) 17a Electrode (multiple electrodes) 17b Electrode (multiple electrodes) 17c Electrode (multiple electrodes) 17d Electrode (multiple) 17e Electrode (plural electrodes) 17f Floating capacitance adjusting electrode (frequency adjusting means) 17g Electrode (plural electrodes) 17h Electrode (plural electrodes) 21 Trimming part (frequency adjusting means, connecting part) 21a Trimming part (frequency Adjustment means, connection part) 23 Shield layer 39 Oscillation circuit (electronic circuit) fout Oscillation frequency VC Varicap (frequency control means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J079 AA04 BA12 BA13 DA11 DA13 FA13 FA14 FA21 FB11 GA03 HA07 HA09 HA14 HA15 HA24 HA25 HA28 HA29 5J108 AA02 BB02 CC04 EE03 EE07 GG03 KK02 KK04 KK05

Claims (8)

[Claims] 1. A piezoelectric vibrating element, a package accommodating the piezoelectric vibrating element and having a stray capacitance, frequency adjusting means for adjusting an oscillation frequency using the stray capacitance of the package, and an applied voltage. And a frequency control means for controlling the oscillation frequency according to the following. 2. The piezoelectric oscillator according to claim 1, wherein the frequency adjusting means is an electrode provided on the package, and adjusts the stray capacitance by changing an area of the electrode. 3. The piezoelectric oscillator according to claim 2, wherein the package is provided with a shield layer surrounding at least a part of the frequency adjusting unit. 4. The frequency adjusting means has a plurality of electrodes and a connecting portion for connecting the plurality of electrodes to each other and exposed to the outside of the package. Or the piezoelectric oscillator according to any one of 3. 5. The piezoelectric oscillator according to claim 1, wherein the frequency adjusting unit is a part of a wiring of an electronic circuit including the piezoelectric vibrating element. 6. The piezoelectric oscillator according to claim 5, wherein said frequency adjusting means is provided between said piezoelectric vibration element and said frequency control means. 7. The piezoelectric oscillator according to claim 2, wherein said frequency adjusting means is a single pole. 8. The piezoelectric oscillator according to claim 1, wherein said frequency control means has a varicap.