JP2018011163A - Oscillator - Google Patents

Abstract

The accuracy of an oscillation signal output from an oscillator is improved. An oscillator 1 oscillates an input terminal 10 for receiving a first oscillation signal from the outside and a crystal resonator 131, thereby having a frequency within a predetermined range with respect to the frequency of the first oscillation signal. An oscillation unit 13 that generates two oscillation signals, and a capacitor 11 and a resistor 12 connected in series between the input terminal 10 and the oscillation unit 13 are included. [Selection] Figure 1

Description

  The present invention relates to an oscillator that outputs an oscillation signal.

  Conventionally, it is known to use a crystal oscillator to generate an oscillation signal. Patent Document 1 discloses an oscillator using a crystal resonator that can oscillate at 32.768 KHz, which is a 1 Hz multiplied wave.

JP 2014-236466 A

  The crystal resonator can oscillate at a designed frequency, but a frequency deviation occurs due to the influence of the capacitance of the capacitor constituting the oscillation circuit and the ambient temperature. Therefore, for example, when a 32.768 KHz oscillation signal used for a timepiece is generated by a crystal oscillator, there is a problem that the time must be periodically corrected.

  Accordingly, the present invention has been made in view of these points, and an object thereof is to improve the accuracy of an oscillation signal output from an oscillator.

  In the first aspect of the present invention, an input unit that receives the input of the first oscillation signal from the outside and oscillating the crystal resonator, the frequency of the first oscillation signal is within a predetermined range. There is provided an oscillator having an oscillating unit for generating a second oscillation signal, and a capacitor and a resistor connected in series between the input unit and the oscillating unit.

  The oscillation unit generates the second oscillation signal having a frequency equal to the frequency of the first oscillation signal while the first oscillation signal is input to the input unit, and the first oscillation is generated at the input unit. While the signal is not input, the second oscillation signal having the free-running frequency of the crystal resonator is generated.

  The resistor may be a variable resistor capable of changing a resistance value. In this case, the oscillation unit generates the second oscillation signal including a jitter having a corresponding magnitude based on the resistance value of the resistor.

  The oscillation unit may include an inverter connected in parallel with the crystal resonator, and the capacitor and the resistor may be provided between the input unit and an input terminal of the inverter.

  According to the present invention, it is possible to improve the accuracy of the oscillation signal output from the oscillator.

1 is a diagram illustrating a configuration of an oscillator 1 according to a first embodiment. It is a figure which shows the structure of the oscillator 2 which concerns on 2nd Embodiment. It is a figure which shows the structure of the oscillator 3 which concerns on 3rd Embodiment. It is a figure which shows the structure of the oscillator 4 which concerns on 4th Embodiment.

<First Embodiment>
[Configuration of Oscillator 1]
FIG. 1 is a diagram illustrating a configuration of an oscillator 1 according to the first embodiment. The oscillator 1 includes an input terminal 10, a capacitor 11, a resistor 12, an oscillation unit 13, an inverter 14, a frequency divider 15, an inverter 16, an output terminal 17, an output terminal 18, and an output terminal 19. Have

  The input terminal 10 is an input unit that receives an oscillation signal input from the outside. In the following description, an oscillation signal input from the outside to the input terminal 10 is referred to as a first oscillation signal. The first oscillation signal is, for example, an oscillation signal superimposed on a radio wave transmitted from a satellite. In this case, the oscillation signal extracted by the receiver that receives radio waves from the satellite is input to the input terminal 10 as the first oscillation signal.

  Although the oscillator 1 illustrated in FIG. 1 does not include a receiver, the oscillator 1 includes a receiver, and an oscillation signal extracted by the receiver included in the oscillator 1 may be used as the first oscillation signal. The frequency of the first oscillation signal is, for example, a frequency multiplied by 32.768 KHz, which is the frequency of the oscillation signal used in a timepiece.

The capacitor 11 removes the direct current component of the first oscillation signal input to the input terminal 10.
The resistor 12 is provided in series with the capacitor 11 between the input terminal 10 and the oscillation unit 13. The resistor 12 attenuates the first oscillation signal.

  The oscillation unit 13 includes an oscillation circuit that generates a second oscillation signal based on the first oscillation signal. Specifically, the oscillating unit 13 includes a crystal resonator 131, a resistor 132, an inverter 133, a capacitor 134, and a capacitor 135. The oscillating unit 13 oscillates the crystal oscillator 131 to generate a second oscillation signal having a frequency within a predetermined range with respect to the frequency of the first oscillation signal.

  The crystal resonator 131 is designed to oscillate at the same frequency as the frequency of the first oscillation signal. The resistor 132 is a feedback resistor provided in parallel at both ends of the crystal resonator 131. The inverter 133 is provided in parallel at both ends of the crystal resonator 131 and the resistor 132. The capacitor 134 and the capacitor 135 are load capacitances, and are provided between both ends of the crystal resonator 131 and the ground.

  While the first oscillation signal having a frequency within a predetermined range is input from the input terminal 10 to the frequency set in advance as the oscillation frequency of the crystal resonator 131 from the input terminal 10, the oscillation unit 13 outputs the first oscillation signal. In synchronization, a second oscillation signal having a frequency equal to the frequency of the first oscillation signal is generated. For example, when the difference between the frequency of the first oscillation signal and the oscillation frequency of the crystal resonator 131 is within 3 ppm, the oscillation unit 13 is drawn into the first oscillation signal and oscillates at the frequency of the first oscillation signal. Start. The oscillation unit 13 generates a second oscillation signal having a free-running frequency of the crystal resonator 131 while the first oscillation signal is not input to the input terminal 10.

  Since the oscillating unit 13 is configured in this way, the oscillating unit 13 outputs the second oscillating signal with high frequency accuracy while the first oscillating signal with high frequency accuracy is input to the input terminal 10. be able to. Even when the first oscillation signal is not input to the input terminal 10, the oscillation unit 13 continuously outputs the second oscillation signal without stopping the output of the second oscillation signal. be able to.

  Note that the degree of phase synchronization between the first oscillation signal and the second oscillation signal is determined by the values of the capacitor 11 and the resistor 12. Further, the second oscillation signal includes a jitter having a magnitude corresponding to the difference between the free-running frequency of the crystal resonator 131 and the frequency of the first oscillation signal, the capacitance value of the capacitor 11, and the resistance value of the resistor 12. As the resistance value of the resistor 12 decreases, the degree of coupling between the first oscillation signal and the oscillation unit 13 increases and the jitter of the second oscillation signal increases.

  The inverter 14 inverts the logic of the second oscillation signal output from the oscillation unit 13 and shapes the second oscillation signal. The inverter 14 inputs the second oscillation signal after inverting the logic to the frequency divider 15. The second oscillation signal output from the inverter 14 is output to the outside via the output terminal 17.

The frequency divider 15 divides the second oscillation signal input from the inverter 14 and generates a 32.768 KHz clock. The frequency divider 15 inputs the generated clock to the inverter 16. The clock output from the frequency divider 15 is output to the outside via the output terminal 18.
The inverter 16 inverts the clock input from the frequency divider 15. The clock inverted by the inverter 16 is output to the outside via the output terminal 19.

  As described above, the oscillator 1 according to the first embodiment has high frequency accuracy through the capacitor 11 and the resistor 12 connected in series to the input stage of the inverter 133 included in the oscillation unit 13, and A first oscillation signal having a frequency close to the free-running frequency of the crystal unit 131 is input.

  Since the oscillator 1 has such a configuration, the oscillating unit 13 can be drawn into the frequency of the first oscillation signal and output the second oscillation signal with high accuracy equal to the frequency of the first oscillation signal. The oscillator 1 can output a high-accuracy 32.768 KHz clock by outputting the second oscillation signal generated by the oscillation unit 13 after the frequency divider 15 divides the frequency, so that it can be output over a long period of time. It is suitable as an oscillator for a watch that requires an operation at a highly accurate frequency.

<Second Embodiment>
FIG. 2 is a diagram illustrating a configuration of the oscillator 2 according to the second embodiment. The oscillator 2 is different from the oscillator 1 in that it has an oscillation unit 23 instead of the oscillation unit 13 of the oscillator 1 according to the first embodiment, and is the same as the oscillator 1 in other points.

  The oscillation unit 23 is a temperature compensated crystal oscillator (TCXO). The oscillation unit 23 includes a variable capacitance element 136 provided between the capacitor 134 and the ground. The variable capacitance element 136 is a varicap diode, for example, and the capacitance value changes according to the voltage at both ends.

  In addition, the oscillation unit 23 includes a temperature compensation circuit 137 that applies a temperature compensation voltage between the capacitor 134 and the variable capacitance element 136. The temperature compensation circuit 137 outputs a temperature compensation voltage that changes according to the ambient temperature. For example, the temperature compensation circuit 137 reduces the capacitance value of the variable capacitance element 136 by increasing the temperature compensation voltage when the ambient temperature increases.

  Since the oscillation unit 23 has the above-described configuration, the capacitance value of the variable capacitance element 136 is decreased even if the self-running frequency of the crystal unit 131 is decreased due to an increase in the ambient temperature. Thus, it is possible to prevent a decrease in the free-running frequency. The configuration of the temperature compensated crystal oscillator is not limited to the configuration shown in FIG. 2, and any configuration that can perform temperature compensation can be applied.

<Third Embodiment>
FIG. 3 is a diagram illustrating a configuration of the oscillator 3 according to the third embodiment. The oscillator 3 is different from the oscillator 1 in that it has an oscillation unit 33 instead of the oscillation unit 13 of the oscillator 1 according to the first embodiment, and is the same as the oscillator 1 in other points.

  The oscillation unit 33 has a Colpitts oscillation circuit. Specifically, the oscillation unit 33 includes a crystal resonator 331, a transistor 332, resistors 333, 334, 335, and 336, and capacitors 337, 338, and 339.

  One end of the crystal unit 331 is connected to the base of the transistor 332, and the other end of the crystal unit 331 is connected to the ground. The resistor 12 is connected to a connection point between the crystal resonator 331 and the base of the transistor 332.

  While the oscillation unit 33 receives a first oscillation signal having a frequency within a predetermined range with respect to a frequency set in advance as the oscillation frequency of the crystal resonator 331 from the input terminal 10, the oscillation unit 33 outputs the first oscillation signal. In synchronization, a second oscillation signal having a frequency equal to the frequency of the first oscillation signal is generated. In addition, the oscillation unit 33 generates a second oscillation signal having a free-running frequency of the crystal resonator 331 while the first oscillation signal is not input to the input terminal 10. Thus, even when the oscillator 3 is an oscillation circuit that does not have an inverter, such as a Colpitts oscillation circuit, the same effects as those of the first embodiment can be obtained.

<Fourth Embodiment>
FIG. 4 is a diagram illustrating a configuration of the oscillator 4 according to the fourth embodiment. The oscillator 3 differs from the oscillator 1 in that the oscillator 3 includes a variable resistor 41 and a control terminal 42 for controlling the resistance value of the variable resistor, instead of the resistor 12 included in the oscillator 1 according to the first embodiment. This is the same as the oscillator 1.

  The variable resistor 41 changes the resistance value according to the voltage of the control signal input from the control terminal 42, for example. As the resistance value of the variable resistor 41 changes, the signal level of the first oscillation signal applied to the oscillating unit 13 changes. When the signal level of the first oscillation signal changes, the jitter amount of the second oscillation signal output from the oscillation unit 13 changes. Therefore, the user of the oscillator 4 can change the jitter amount of the second oscillation signal by changing the voltage of the control signal applied to the control terminal 42.

  Thus, the oscillator 4 can change the jitter amount of the second oscillation signal by having the variable resistor 41 between the input terminal 10 to which the first oscillation signal is input and the oscillation unit 13. Therefore, the oscillator 4 is suitable for a circuit that needs to reduce the peak level of radiation noise (EMI: Electro-Magnetic Interference) caused by the second oscillation signal.

In the above description, the example in which the control signal is input from the control terminal 42 has been described. However, the oscillator 4 physically uses the tool inserted through the control terminal 42 to set the resistance value of the variable resistor 41 physically. You may have the structure of adjusting.
The configuration of the fourth embodiment can also be applied to the second and third embodiments. The resistor 12 in the oscillator 2 and the oscillator 3 is a variable resistor, so that the fourth embodiment can be used. The same effect as the oscillator 4 according to the above can be obtained.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

1, 2, 3, 4 Oscillator 10 Input terminal 11 Capacitor 12 Resistor 13 Oscillator 14 Inverter 15 Divider 16 Inverter 17, 18, 19 Output terminal 23 Oscillator 33 Oscillator 41 Variable resistor 42 Control terminal 131 Crystal resonator 132 Resistor 133 Inverter 134 Capacitor 135 Capacitor 136 Variable capacitance element 137 Temperature compensation circuit 331 Crystal oscillator 332 Transistors 333, 334, 335, 336 Resistor 337, 338, 339 Capacitor

Claims (5)

An input unit for receiving the first oscillation signal from the outside;
An oscillation unit that generates a second oscillation signal having a frequency within a predetermined range with respect to the frequency of the first oscillation signal by oscillating a crystal resonator;
A capacitor and a resistor connected in series between the input unit and the oscillation unit;
Having an oscillator. The oscillation unit generates the second oscillation signal having a frequency equal to the frequency of the first oscillation signal while the first oscillation signal is input to the input unit, and the first oscillation is generated at the input unit. While the signal is not input, the second oscillation signal having the free-running frequency of the crystal resonator is generated.
The oscillator according to claim 1. The resistor is a variable resistor capable of changing a resistance value.
The oscillator according to claim 1 or 2. The oscillation unit generates the second oscillation signal including a jitter having a corresponding magnitude based on a resistance value of the resistor;
The oscillator according to claim 3. The oscillation unit has an inverter connected in parallel with the crystal resonator,
The capacitor and the resistor are provided between the input unit and the input terminal of the inverter.
The oscillator according to any one of claims 1 to 4.

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