JP2015173310A - crystal oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal oscillator capable of outputting a stable frequency signal by suppressing the influence of acceleration from the outside.SOLUTION: The crystal oscillator includes a reference signal generation unit for generating a reference signal and a voltage-controlled oscillator unit for outputting a specific frequency signal on the basis of the reference signal. The reference signal generation unit includes: a crystal oscillation circuit part 2 and a crystal oscillation circuit part 3 which include the same crystal piece; a frequency mixer circuit which mixes frequency signals from the crystal oscillation circuit parts 2 and 3 and outputs the mixed signal as the reference signal; and a substrate 1 on which the crystal oscillation circuit parts 2 and 3 are mounted. The crystal oscillation circuit part 2 is mounted on the substrate 1 in an upright state, and the crystal oscillation circuit part 3 is mounted on the substrate 1 in an inverted state.

Description

  The present invention relates to a crystal oscillator, and more particularly to a crystal oscillator that can suppress the influence of external acceleration and can output a frequency signal with good characteristics.

[Description of Prior Art]
The crystal oscillator has acceleration sensitivity that generates a specific amount of frequency fluctuation when acceleration in a specific direction is applied to the cutting angle of the crystal piece, and the frequency fluctuates due to the influence of external acceleration.
The acceleration sensitivity has directivity in a specific direction, and the output frequency characteristic may vary greatly depending on the orientation in which the crystal oscillator is installed.
Furthermore, depending on the application, the change in acceleration from the outside is large, and the influence of acceleration sensitivity may be large.
In order to reduce the acceleration sensitivity, the crystal piece may be reduced in size. However, since the frequency stability (especially the aging characteristics) deteriorates when the size is reduced, there is a limit to downsizing.

[Related technologies]
As a prior art of an oscillator that compensates for frequency fluctuations due to acceleration, there is Japanese Unexamined Patent Application Publication No. 2010-206346, “vibration compensation type crystal oscillator” (Nippon Denpa Kogyo Co., Ltd., Patent Document 1).
Patent Document 1 describes a crystal oscillator that includes an acceleration sensor using a MEMS microphone, detects acceleration due to external vibrations to the crystal resonator, and compensates for frequency fluctuation due to the acceleration.

JP 2010-206346 A

  As described above, the conventional crystal oscillator has a problem that the output frequency fluctuates due to external vibration or acceleration due to gravity depending on the acceleration sensitivity of the crystal piece.

  Note that Patent Document 1 does not describe that the quartz oscillation circuit units of the same standard are mounted face to face with the substrate interposed therebetween, and the frequency signals output from each are mixed to cancel the acceleration sensitivity. .

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a crystal oscillator capable of suppressing the influence of external acceleration and outputting a stable frequency signal.

  The present invention for solving the problems of the conventional example is a crystal oscillator including a reference signal generation unit that generates a reference signal, and a voltage-controlled oscillator unit that generates and outputs a frequency signal based on the reference signal. The reference signal generation unit includes a first crystal oscillation circuit unit and a second crystal oscillation circuit unit including the same crystal piece, a frequency signal from the first crystal oscillation circuit unit, and a second crystal oscillation. A frequency mixer circuit that mixes frequency signals from the circuit unit and outputs the mixed signal as a reference signal; and a substrate on which the first crystal oscillation circuit unit and the second crystal oscillation circuit unit are mounted. The circuit unit is mounted on the substrate in an upright state, and the second crystal oscillation circuit unit is mounted on the substrate in an inverted state.

  According to the present invention, in the crystal oscillator, the frequency mixer circuit includes a low-frequency filter, and outputs a low-frequency component of the mixed signal.

  According to the present invention, in the crystal oscillator, the second crystal oscillation circuit unit is mounted on the surface of the substrate opposite to the first crystal oscillation circuit unit so as to face the first crystal oscillation circuit unit. It is characterized by being.

  According to the present invention, in the crystal oscillator described above, an acceleration sensor for detecting acceleration and a frequency signal from the first and second crystal oscillation circuit units are input, and one of the frequency signals is selected and a reference signal is selected. When the cancellation mode is set by the switch, the selection circuit that outputs as the operation mode, the switch that sets either the cancellation mode or the selection mode as the operation mode, the first and second crystal oscillation circuit units A switching circuit that outputs a frequency signal to the frequency mixer circuit and outputs a frequency signal to the selection circuit when the selection mode is set, and the selection circuit is included in the first or second crystal oscillation circuit unit. The method is characterized in that the one having the lower sensitivity to the acceleration detected by the acceleration sensor is selected and the frequency signal from the selected crystal oscillation circuit unit is output.

  Further, the present invention is a crystal oscillator including a reference signal generation unit that generates a reference signal and a voltage-controlled oscillator unit that generates and outputs a frequency signal based on the reference signal, and the reference signal generation unit includes: Select one of multiple crystal oscillation circuit units with the same crystal piece, a substrate on which the crystal oscillation circuit unit is mounted, an acceleration sensor that detects acceleration, and frequency signals from multiple crystal oscillation circuit units. And a plurality of crystal oscillation circuit units are mounted on the substrate so that the angles of the crystal pieces are different from each other, and the selection circuit includes the plurality of crystal oscillation circuit units. The crystal oscillation circuit unit having the lowest sensitivity to the acceleration detected by the acceleration sensor is selected from the inside, and the frequency signal from the crystal oscillation circuit unit is output.

  Further, the present invention is characterized in that the crystal oscillation circuit section is mounted on each of the xy plane, the yz plane, and the xz plane.

  According to the present invention, a crystal oscillator including a reference signal generation unit that generates a reference signal and a voltage-controlled oscillator unit that generates and outputs a frequency signal based on the reference signal, the reference signal generation unit includes: The first crystal oscillation circuit unit and the second crystal oscillation circuit unit including the same crystal piece, and the frequency signal from the first crystal oscillation circuit unit and the frequency signal from the second crystal oscillation circuit unit are mixed. And a substrate on which the first crystal oscillation circuit unit and the second crystal oscillation circuit unit are mounted, and the first crystal oscillation circuit unit is in an upright state. Since the second crystal oscillation circuit unit mounted on the substrate is a crystal oscillator mounted on the substrate in an inverted state, the two crystal pieces are mounted upside down, and at least Cancel the acceleration sensitivity in the direction By reducing the influence of the acceleration from the can produce high stability reference signal, an effect which can output a good stable frequency signal characteristics.

  According to the present invention, in the crystal oscillator, an acceleration sensor for detecting acceleration and a frequency signal from the first and second crystal oscillation circuit units are input, and one of the frequency signals is selected, A selection circuit that outputs as a reference signal, a switch that sets either the cancellation mode or the selection mode as an operation mode, and the first and second crystal oscillation circuit sections when the cancellation mode is set by the switch And a switching circuit that outputs the frequency signal to the selection circuit when the selection mode is set, and the selection circuit includes the first or second crystal oscillation circuit unit. Of these, the crystal oscillator that selects the lower sensitivity to the acceleration detected by the acceleration sensor and outputs the frequency signal from the selected crystal oscillation circuit section. By selecting the mode according to the application and required characteristics, there is an effect that it is possible to output a high frequency signal characteristics by the desired operation.

  According to the present invention, there is provided a crystal oscillator comprising a reference signal generation unit that generates a reference signal and a voltage controlled oscillator unit that generates and outputs a frequency signal based on the reference signal, the reference signal generation unit Is selected from a plurality of crystal oscillation circuit units having the same crystal piece, a substrate on which the crystal oscillation circuit unit is mounted, an acceleration sensor for detecting acceleration, and a frequency signal from the plurality of crystal oscillation circuit units. And a plurality of crystal oscillation circuit units are mounted on the substrate so that the angles of the crystal pieces are different from each other, and the selection circuit includes a plurality of crystal oscillation circuits. The crystal oscillator circuit unit that is the least sensitive to the acceleration detected by the acceleration sensor is selected from these units, and the crystal oscillator that outputs the frequency signal from the crystal oscillator circuit unit is used. By reducing the influence of the degree it can be generated with high stability reference signal, an effect which can output a good stable frequency signal characteristics.

It is sectional drawing which shows schematic structure of the crystal oscillator which concerns on the 1st Embodiment of this invention. It is a circuit block block diagram of a 1st crystal oscillator. It is a circuit block diagram of the crystal oscillator based on the 2nd Embodiment of this invention.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
A crystal oscillator according to an embodiment of the present invention is a crystal oscillator including a reference signal generation unit that generates a reference signal and a voltage-controlled oscillator unit that outputs a specific frequency signal based on the reference signal. The signal generation unit includes the same crystal piece, and the first and second crystal oscillation circuit units mounted on the front and back surfaces of the substrate, respectively, and output frequency signals from the first and second crystal oscillation circuit units And a frequency mixer circuit unit that extracts low frequency components as a reference signal by mixing the two, and the crystal pieces in the two crystal oscillation circuit units are upside down, so frequency fluctuations due to acceleration sensitivity in the vertical direction The reference signal with reduced influence of external acceleration can be generated and supplied to the voltage controlled oscillator unit, and a stable frequency signal with good characteristics can be output.

  Further, in the crystal oscillator according to the embodiment of the present invention, the reference signal generation unit includes a plurality of crystal oscillation circuit units having different mounting directions on the substrate, and the influence of the acceleration is based on the acceleration detected by the acceleration sensor. Selects the output from the crystal oscillation circuit section where the signal becomes smaller and outputs it as a reference signal, reducing the influence of external acceleration and outputting a good frequency signal based on a stable reference frequency signal Is.

[First Embodiment: FIG. 1]
A crystal oscillator according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the crystal oscillator according to the first embodiment of the present invention.
As shown in FIG. 1, the crystal oscillator (first crystal oscillator) according to the first embodiment of the present invention basically includes a crystal oscillation circuit unit 2 and a crystal resonator on the upper surface of a main substrate 1. 4 and the control circuit IC 5 are mounted, the crystal oscillation circuit unit 3 is mounted on the lower surface of the main substrate 1, and the main substrate 1 on which various components are mounted is covered with the metal cover 6. Although omitted in the figure, the bottom surface of the metal cover 6 is a base.

  And the main board | substrate 1 is fixed to the base of the bottom face part of the metal cover 6 with the pin 13, and is connected to the foot pattern 61 provided in the back surface of the base. Here, an SMD (Surface Mount Device) type foot pattern is used, but a pin type may be used.

Each part will be described.
In the crystal oscillation circuit unit 2, the crystal resonator 21 and the oscillation circuit IC 22 are mounted on one surface of the sub-board 20, and the whole is covered with the metal cover 25. The sub-board 20 is covered with the metal cover 25 by the pins 23. Are fixed to the lower base and further connected to the foot pattern 11 on the back surface of the base. The foot pattern 11 may be SMD type or lead type.

The crystal resonator 21 has a crystal piece and oscillates a frequency. Although the SMD type is shown here, a lead type may be used.
The oscillation circuit IC22 is an IC on which an oscillation circuit, a buffer, a temperature control circuit, a temperature compensation circuit, and other circuit elements such as individual components and modules are mounted, and performs oscillation control, temperature compensation control, and the like.

  Similarly, in the crystal oscillation circuit unit 3, the crystal resonator 31 and the oscillation circuit IC 32 are mounted on one surface of the sub-board 30, and the whole is covered with a metal cover 35. The metal cover 35 is fixed to the base (corresponding to the upper surface in FIG. 1) and connected to the foot pattern 12.

As a feature of the first crystal oscillator, the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3 are basically of the same design (same type) using the same crystal piece and electronic component, The main board 1 is mounted on the upper and lower surfaces.
In the example of FIG. 1, the crystal oscillation circuit unit 2 is mounted on the upper surface of the main substrate 1 in an upright state, and the crystal oscillation circuit unit 3 is in the upside down state (inverted state, inverted state). It is mounted on the lower surface of the substrate 1.

With the inverted state, the direction of the crystal piece of the crystal oscillation circuit unit 3 is opposite to that of the crystal piece of the crystal oscillation circuit unit 2.
In addition, since the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3 have the same configuration, either left and right or front and rear (depth direction) are reversed in addition to top and bottom.
In FIG. 1, the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3 show a state in which the direction of the internal crystal piece is inverted 180 degrees up and down and front and back. In this case, the directions in the left-right direction are the same.

By mounting in this way, in the example of FIG. 1, when acceleration is applied from the outside, forces in opposite directions are exerted on the two crystal pieces in the vertical direction and the front-rear (depth) direction. The direction of frequency fluctuation due to the direction acceleration component is also opposite.
As an example of mounting the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3, the top and bottom and the left and right may be reversed.
In any case, since the two crystal pieces are mounted so as to be inverted in the vertical direction, it is possible to cancel the influence of the acceleration due to the vertical vibration or the like.

Further, when mounting the first crystal oscillator on the product substrate, it is desirable to mount the first crystal oscillator so that the acceleration sensitivity in an appropriate direction is canceled according to the application.
At that time, the direction of the first crystal oscillator is such that the influence of acceleration is large in the product and the direction in which the influence is desired to be reduced coincides with the direction in which the crystal pieces of the crystal oscillation circuit units 2 and 3 are inverted. Can be implemented together.

  In FIG. 1, the crystal oscillation circuit unit 3 is mounted to face the crystal oscillation circuit unit 2 with the main substrate 1 interposed therebetween, but without being opposed, for example, under the crystal resonator 4 or the control circuit IC 5. May be installed.

Further, here, the crystal oscillation circuit unit 3 is mounted on the lower surface of the main substrate 1, but the crystal oscillation circuit unit 3 may be mounted on the upper surface of the main substrate 1 as long as it can be mounted in an inverted state. .
Similarly, if possible, the crystal oscillation circuit unit 2 may be mounted on the lower surface of the main board 1 in an upright posture.

  In the first crystal oscillator, two frequencies that fluctuate in opposite directions are mixed to extract a frequency in which fluctuations due to acceleration components in two directions are canceled (hereinafter simply referred to as “fluctuation is canceled”). Is used as a reference signal. The crystal oscillation circuit units 2 and 3 and a frequency mixer described later constitute a reference signal generation unit that generates a reference signal.

Further, in the crystal oscillation circuit units 2 and 3, not only the crystal piece but also the buffer, the temperature control circuit, the temperature compensation circuit, and the like have the same standard, and the characteristic difference other than the acceleration sensitivity is suppressed.
Here, although the crystal oscillation circuit units 2 and 3 are temperature compensated crystal oscillators (TCXO), such as SPXO (Simple Packaged Crystal Oscillator), VCXO (Voltage Controlled Crystal Oscillator), OCXO (Oven Controlled Crystal Oscillator), etc. Other types may be used.

  The crystal resonator 4 is a resonator constituting a voltage-controlled crystal oscillator (VCXO) together with an oscillation circuit provided in the control circuit IC5. The VCXO outputs a frequency signal corresponding to the control voltage.

  The control circuit IC5 is an IC including a VCXO oscillation circuit, a PLL circuit, a frequency mixer, and other circuits and elements. The PLL circuit is based on the phase difference between the reference signal and the output signal from the crystal unit 4. Thus, a control voltage for the VCXO is generated, and the output of the VCXO is controlled to have a constant frequency.

  The frequency mixer provided in the control circuit IC5 is a characteristic part of the first crystal oscillator, mixes and detects the output signal from the crystal oscillation circuit unit 2 and the output signal from the crystal oscillation circuit unit 3, The band is limited and output. The frequency mixer will be described later.

[Circuit block diagram: FIG. 2]
Next, the circuit block configuration of the first crystal oscillator will be described with reference to FIG. FIG. 2 is a circuit block diagram of the first crystal oscillator.
As shown in FIG. 2, the first crystal oscillator includes a crystal oscillation circuit unit 2 including a crystal resonator X1 and an oscillation circuit unit 22, and a crystal oscillation circuit including a crystal resonator X2 and an oscillation circuit unit 32. Unit 3, a frequency mixer circuit 51, a crystal resonator X3, and a VCXO oscillation circuit unit 52.
The configuration including the crystal oscillation circuit unit 2, the crystal oscillation circuit unit 3, and the frequency mixer circuit 51 corresponds to the reference signal generation unit described in the claims, and the crystal resonator X3 and the VCXO oscillation circuit unit 52 are voltage controlled oscillator units. It corresponds to. The crystal oscillation circuit unit 2 corresponds to the first crystal oscillation circuit unit, and the crystal oscillation circuit unit 3 corresponds to the second crystal oscillation circuit unit.

The crystal resonators X1 and X2 correspond to the crystal resonators 21 and 31 of FIG. 1, and output frequency signals f1 and f2, respectively.
Further, the frequency mixer circuit 51 and the VCXO oscillation circuit unit 52 are provided in the control circuit IC5 of FIG.
The VCXO oscillation circuit unit 52 is also provided with a PLL circuit and other elements.

The frequency mixer circuit 51 basically includes a multiplier, a detector, and a low-frequency filter. The frequency mixer circuit 51 mixes the output signals of the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3 with the multiplier and mixes with the detector. The waveform is detected and a low frequency component is extracted by a low frequency filter.
Specifically, the output signal f3 of the frequency mixer circuit 51 is f3 = f1−f2.

If the crystal resonators X1 and X2 are affected by acceleration from the outside and cause deviations Δf1 and Δf2, respectively, the crystal resonators X1 and X2 are mounted in a state where they are inverted by 180 degrees in two directions. Therefore, the influence of the acceleration in the two directions is also reversed, and the acceleration sensitivity of the individual crystal oscillation circuit units 2 and 3 is canceled out. That is, Δf1 and Δf2 are substantially canceled at the mixed frequency (f1-f2).
As a result, the output frequency signal f3 from the frequency mixer circuit 51 has a reduced frequency deviation due to the influence of acceleration.

The frequency signal f3 is input as a reference signal to the PLL circuit of the VCXO oscillation circuit unit 52, and a desired frequency signal is output by the VCXO including the crystal resonator X3.
Possible uses include, for example, in-vehicle wireless devices, aeronautical wireless devices, commercial wireless devices, communication base stations, and the like.

[Effect of the first embodiment]
According to the crystal oscillator according to the first embodiment of the present invention, the same crystal oscillation circuit unit 2 and crystal oscillation circuit unit 3 are in an upright state and an inverted state on the upper surface and the lower surface of the main substrate 1, respectively. The frequency mixer circuit 51 mixes and detects the output signals of the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3, extracts the low-frequency component f1-f2, and uses the VCXO oscillation circuit unit 52 as a reference signal. Since the crystal oscillator supplied to the PLL circuit is used, the acceleration sensitivities of the two crystal oscillation circuit units 2 and 3 cancel each other, and the influence of external acceleration is reduced to generate a stable reference signal f3. Therefore, there is an effect that an output frequency signal having good characteristics can be obtained.

[Second Embodiment: FIG. 3]
Next, a crystal oscillator according to a second embodiment of the invention will be described with reference to FIG. FIG. 3 is a circuit block diagram of the crystal oscillator according to the second embodiment of the present invention.
The crystal oscillator (second crystal oscillator) according to the second embodiment of the present invention includes a plurality of crystal oscillation circuit units whose mounting directions are changed, and has a direction in which the acceleration sensitivity is the smallest with respect to the detected acceleration. The mounted crystal oscillation circuit section is selected and its output signal is output as a reference signal, and the influence of acceleration can be reduced even when the acceleration changes every moment.

As shown in FIG. 3, the second crystal oscillator includes crystal oscillation circuit units 7a, 7b and 7c as the crystal oscillation circuit unit 7, an acceleration sensor 74, a selection circuit 75, a VCXO oscillation circuit IC76, and a crystal oscillation. And a child X7.
Among the above-described configurations, the VCXO oscillation circuit unit 76 and the crystal resonator X7 have the same configurations and operations as the first crystal oscillator described above, and thus description thereof is omitted.

  The crystal oscillation circuit unit 7a includes a crystal resonator X4 and an oscillation circuit IC71, the crystal oscillation circuit unit 7b includes a crystal resonator X5 and an oscillation circuit IC72, and the crystal oscillation circuit unit 7c includes a crystal resonator X6. The three crystal oscillation circuit portions 7a, 7b, and 7c are all of the same standard. Each component is mounted on the main board.

As a feature of the second crystal oscillator, the three crystal oscillation circuit units 7a, 7b, and 7c are respectively installed in different planes inside the second crystal oscillator.
For example, the crystal oscillation circuit unit 7a is installed on the xy plane, the crystal oscillation circuit unit 7b is installed on the yz plane, and the crystal oscillation circuit unit 7c is installed on the xz plane.
Specifically, in the second crystal oscillator, substrates are provided on the xy plane, the yz plane, and the xz plane, and the crystal oscillation circuit units 7a, 7b, and 7c are mounted on the respective substrates. That is, each crystal oscillation circuit unit is mounted in a posture orthogonal to each other.
Note that any of the xy, yz, and xz plane substrates may be used as the main substrate.

The acceleration sensor 74 detects the direction and magnitude of the acceleration from the outside and outputs it to the selection circuit.
As the acceleration sensor 74, for example, there is one that uses quartz as a sensor element to detect gravity, acceleration due to a moving body, and the like by frequency.

  Based on the information from the acceleration sensor 74, the selection circuit 75 selects one of the three crystal oscillation circuit units 7a, 7b, and 7c that has the least influence of acceleration, and selects the selected crystal oscillation circuit unit. The output frequency signal is output to the VCXO oscillation circuit unit 76 as a reference signal.

Specifically, the selection circuit 75 determines the acceleration in each direction for the crystal oscillation circuit units 7a, 7b, and 7c installed in different directions based on the characteristics of the crystal pieces mounted on each crystal oscillation circuit unit 7. Corresponding sensitivity (frequency change amount) is stored.
Based on the acceleration information from the acceleration sensor 74, the crystal oscillation circuit unit 7 having the lowest sensitivity to the acceleration in the direction and the smallest frequency variation is selected.

  That is, the selection circuit 75 selects the crystal oscillation circuit unit 7 that is mounted in the direction in which the acceleration sensitivity is the lowest with respect to the acceleration from the outside and the frequency fluctuation is small, and the output frequency signal of the crystal oscillation circuit unit 7 is selected. Is supplied to the VCXO oscillation circuit section 76.

  Thereby, in the second crystal oscillator, even in an environment where the acceleration changes every moment, it is possible to select the crystal oscillation circuit unit 7 that minimizes the influence, suppressing frequency fluctuation due to the acceleration from the outside, A stable reference signal can be generated and a good frequency signal can be output from the VCXO.

  Here, the number of the crystal oscillation circuit units 7 is three, but may be four or more or two according to the application and required characteristics.

  Further, the selection circuit 75 stores only information on acceleration sensitivity of the crystal oscillation circuit unit 7 mounted on a specific surface (for example, the xy plane), and the crystal oscillation circuit mounted on another surface by arithmetic processing. The acceleration sensitivity in the unit 7 may be calculated, and the crystal oscillation circuit unit 7 that minimizes the frequency shift may be selected.

[Effect of second crystal oscillator]
The crystal oscillator according to the second embodiment of the present invention includes a plurality of crystal oscillation circuit units 7a, 7b, and 7c mounted on three orthogonal surfaces, and the selection circuit 75 includes each crystal oscillation circuit unit 7. Information on acceleration sensitivity is stored, and based on the direction of acceleration detected by the acceleration sensor 74, the crystal oscillation circuit unit 7 having the minimum sensitivity to the acceleration is selected, and the selected crystal oscillation circuit unit 7 is selected. Is output as a reference signal to the VCXO oscillation circuit unit 76, so that the influence of external acceleration is reduced, a stable reference signal is supplied, and a frequency signal with good characteristics is output. There is an effect that can be done.

[Combination of first crystal oscillator and second crystal oscillator]
Furthermore, it is possible to adopt a configuration in which the first crystal oscillator and the second crystal oscillator are combined.
In this case, an operation mode (cancellation mode) that cancels the acceleration sensitivity that is the operation of the first crystal oscillator, and an operation that selects a plurality of crystal oscillation circuit units that have a low acceleration sensitivity from the operation of the second crystal oscillator. Both operation modes of the mode (selection mode) are prepared, and the operation in the mode selected by switching the switch or the like is performed.

  For example, in addition to the configuration of FIG. 2, the acceleration sensor 74 and the selection circuit 75 of FIG. 3 are further provided, and a switching circuit is provided, and frequency signals from the crystal oscillation circuit unit 2 and the crystal oscillation circuit unit 3 are input to the switching circuit. This can be realized by configuring the switching circuit to output to the frequency mixer circuit 51 in the cancellation mode and to the selection circuit 75 in the selection mode according to the operation mode selected by the switch. .

With such a configuration, when the cancellation mode is selected, the same operation as that of the first crystal oscillator is performed. When the selection mode is selected, the selection circuit 75 causes the acceleration from the acceleration sensor 74 to be accelerated. The output of either the crystal oscillation circuit unit 2 or the crystal oscillation circuit unit 3 is selected and output according to the information.
As a result, a frequency signal having a desired characteristic can be output by appropriately selecting a mode according to the required characteristic.

  The present invention is suitable for a crystal oscillator that can suppress the influence of external acceleration and can output a frequency signal with good characteristics.

  DESCRIPTION OF SYMBOLS 1 ... Main board | substrate, 2, 3, 7 ... Crystal oscillation circuit part, 4, 21, 31 ... Crystal oscillator, 5 ... Control circuit IC, 52,76 ... VCXO oscillation circuit part 6, 25, 35 ... metal cover, 11, 12, 61 ... foot pattern, 22, 32, 71, 72, 73 ... oscillation circuit IC, 13 ... pin, 20, 30 ... Sub-board, 51 ... Frequency mixer circuit, 74 ... Accelerometer, 75 ... Selection circuit

Claims (6)

A crystal oscillator comprising a reference signal generating unit that generates a reference signal, and a voltage controlled oscillator unit that generates and outputs a frequency signal based on the reference signal,
The reference signal generation unit includes a first crystal oscillation circuit unit and a second crystal oscillation circuit unit including the same crystal piece;
A frequency mixer circuit that mixes a frequency signal from the first crystal oscillation circuit unit and a frequency signal from the second crystal oscillation circuit unit, and outputs the mixed signal as the reference signal;
A substrate on which the first crystal oscillation circuit unit and the second crystal oscillation circuit unit are mounted;
The first crystal oscillation circuit unit is mounted on the substrate in an upright state, and the second crystal oscillation circuit unit is mounted on the substrate in an inverted state.   2. The crystal oscillator according to claim 1, wherein the frequency mixer circuit includes a low-frequency filter and outputs a low-frequency component of the mixed signal.   The second crystal oscillation circuit unit is mounted on a surface of the substrate opposite to the first crystal oscillation circuit unit so as to face the first crystal oscillation circuit unit. The crystal oscillator according to 1 or 2. An acceleration sensor for detecting acceleration;
A selection circuit that inputs a frequency signal from the first and second crystal oscillation circuit units, selects one of the frequency signals, and outputs the selected signal as a reference signal;
A switch for setting either the cancellation mode or the selection mode as the operation mode;
When the cancellation mode is set by the switch, the frequency signal from the first and second crystal oscillation circuit units is output to the frequency mixer circuit, and when the selection mode is set, the frequency signal And a switching circuit that outputs to the selection circuit,
The selection circuit selects one of the first and second crystal oscillation circuit units that has a lower sensitivity to the acceleration detected by the acceleration sensor, and the frequency from the selected crystal oscillation circuit unit 4. The crystal oscillator according to claim 1, wherein a signal is output. A crystal oscillator comprising a reference signal generating unit that generates a reference signal, and a voltage controlled oscillator unit that generates and outputs a frequency signal based on the reference signal,
A plurality of crystal oscillation circuit units including the same crystal piece, and the reference signal generation unit;
A substrate on which the crystal oscillation circuit unit is mounted;
An acceleration sensor for detecting acceleration;
A selection circuit that selects any one of frequency signals from the plurality of crystal oscillation circuit units and outputs the selected signal as the reference signal;
The plurality of crystal oscillation circuit units are mounted on the substrate so that the angles of the crystal pieces are different from each other,
The selection circuit selects a crystal oscillation circuit unit having the lowest sensitivity to the acceleration detected by the acceleration sensor from the plurality of crystal oscillation circuit units, and outputs a frequency signal from the crystal oscillation circuit unit. A crystal oscillator characterized by output.   6. The crystal oscillator according to claim 5, wherein the crystal oscillation circuit unit is mounted on each of the xy plane, the yz plane, and the xz plane.

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