JP2015012358A - Atomic oscillator, electronic apparatus, mobile body and gps module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an atomic oscillator that consumes less power and is manufacturable at a suppressed cost.SOLUTION: An atomic oscillator 3 includes: a quantum interference device 10; a PLL circuit 20 having an oscillator 24 and a multiplier 25 for multiplying an oscillation frequency output from the oscillator 24 by a factor of n; and an amplifier 6. A filter section 30 for passing a predetermined frequency output from the multiplier 25 and attenuating a frequency that is half the predetermined frequency is further connected between the PLL circuit 20 and the quantum interference device 10.

Description

  The present invention relates to an atomic oscillator, an electronic device using the atomic oscillator, a mobile object, and a GPS module.

  2. Description of the Related Art Atomic oscillators that oscillate based on energy transitions of alkali metal atoms such as rubidium and cesium are known. In general, the operating principles of atomic oscillators are broadly divided into methods that use the double resonance phenomenon of light and microwaves, and methods that use the quantum interference effect (CPT: Coherent Population Trapping) of two types of light with different wavelengths. Is done.

  In both types of atomic oscillators, alkali metal is sealed in a gas cell together with a buffer gas, and how much light incident on the gas cell is absorbed by the alkali metal is detected by a detector provided on the opposite side. Thus, the atomic resonance is detected, and the detected atomic resonance is output as a reference signal by the control system. 2. Description of the Related Art Conventionally, as described in, for example, Patent Document 1, an atomic oscillator including a PLL (Phase Locked Loop) circuit having a voltage controlled oscillator that outputs a microwave frequency incident on an atomic resonator including a gas cell is known. It was done.

  In addition, since an atomic oscillator using CPT is smaller than an atomic oscillator using a double resonance phenomenon, it is expected to incorporate an atomic oscillator into various electronic devices. Power consumption is desired.

JP 2011-244120 A

  However, the atomic oscillator described in Patent Document 1 uses a voltage-controlled oscillator that directly oscillates in the microwave band, and there is a problem that it is difficult to reduce power consumption and reduce manufacturing costs. . Specifically, in general, an oscillator has a higher loss in a circuit element such as a transmission line as the oscillation frequency becomes higher, and accordingly, the Q factor of the resonance circuit is deteriorated and the output power is lowered. The decrease in output power needs to be compensated for by an amplifier provided in the subsequent stage of the oscillator, which increases the power consumption of the atomic oscillator. In addition, high-precision manufacturing / assembly / mounting technology is required to realize desired characteristics, and the higher the frequency, the higher the procurement cost of the voltage controlled oscillator.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 An atomic oscillator according to this application example includes a quantum interference device, a PLL circuit having an oscillator, and a multiplier that multiplies an oscillation frequency output from the oscillator, and an amplifier. It is characterized by.

  According to this application example, the atomic oscillator includes a quantum interference device, a PLL circuit that generates a predetermined frequency incident on the quantum interference device, and an amplifier. In general, an oscillator of a PLL circuit has a lower Q factor of a resonant circuit and a lower output power as an oscillation frequency becomes higher. The decrease in output power needs to be compensated by an amplifier provided in the subsequent stage of the oscillator, which increases power consumption. In addition, an oscillator that can oscillate at a higher frequency is more expensive and the manufacturing cost of the atomic oscillator increases. Therefore, in this application example, since the PLL circuit includes a multiplier that multiplies the oscillation frequency output from the oscillator by n, an oscillator that oscillates at a frequency 1 / n lower than the conventional oscillator is used. can do. Therefore, it is possible to provide an atomic oscillator that can reduce power consumption and reduce manufacturing costs.

  Application Example 2 The atomic oscillator according to the application example described above passes a predetermined frequency output from the multiplier between the PLL circuit and the quantum interference device, and has a frequency that is ½ of the predetermined frequency. It is preferable that a filter part for attenuating is connected.

  According to this application example, the atomic oscillator includes a multiplier that multiplies the oscillation frequency output from the oscillator by n in the PLL circuit. Therefore, the frequency component output from the multiplier is 1 / n of the predetermined frequency. m times (m = 1, 2, 3,...). The inventor has found through experiments that the frequency stability of the atomic oscillator deteriorates when a frequency that is half the predetermined frequency is input to the quantum interference device. Therefore, in the present embodiment, a filter unit that passes a predetermined frequency and attenuates a half of the predetermined frequency is further connected between the PLL circuit and the quantum interference device. As a result, it is possible to provide an atomic oscillator that reduces power consumption and suppresses manufacturing costs without degrading frequency stability.

  Application Example 3 In the atomic oscillator according to the application example described above, the output power output from the filter unit at the predetermined frequency is 1/2 of the predetermined frequency and 1.5 times the predetermined frequency. A relative comparison with the output power output is preferably 15 dB or more.

  According to this application example, the atomic oscillator has a relative relationship between the power output from the filter unit at a predetermined frequency and the power output at a frequency that is 1/2 the predetermined frequency and 1.5 times the predetermined frequency. Since the filter unit having a comparison of 15 dB or more is connected, an atomic oscillator having desired frequency stability, reducing power consumption, and suppressing manufacturing cost can be provided.

  Application Example 4 In the atomic oscillator described in the application example, the quantum interference device includes a metal atom, a gas cell in which the metal atom is sealed, and a resonant light pair that generates an electromagnetically induced transmission phenomenon in the metal atom. It is preferable to have a light source that irradiates light including the light source and a light detection unit that detects the light that has passed through the metal atom.

  According to this application example, the quantum interference device provided in the atomic oscillator includes a metal atom, a cell, a light source, and a light detection unit. In general, an oscillator of a PLL circuit has a lower Q factor of a resonant circuit and a lower output power as an oscillation frequency becomes higher. The decrease in output power needs to be compensated by an amplifier provided in the subsequent stage of the oscillator, which increases power consumption. In addition, an oscillator that can oscillate at a higher frequency is more expensive and the manufacturing cost of the atomic oscillator increases. Therefore, in this application example, since the PLL circuit includes a multiplier that multiplies the oscillation frequency output from the oscillator by n, an oscillator that oscillates at a frequency 1 / n lower than the conventional oscillator is used. can do. Therefore, it is possible to provide an atomic oscillator that can reduce power consumption and reduce manufacturing costs.

  Application Example 5 In the atomic oscillator according to the application example described above, the light source is preferably a semiconductor laser.

  According to this application example, the atomic oscillator has a semiconductor laser light source, and the PLL circuit uses an oscillator that oscillates at a frequency 1 / n lower than that of a conventional oscillator. An atomic oscillator capable of reducing the manufacturing cost can be provided.

  Application Example 6 In the atomic oscillator described in the above application example, it is preferable that the light source is a vertical cavity surface emitting laser and the metal atom is cesium.

  According to this application example, the atomic oscillator has a vertical cavity surface emitting laser (VCSEL) light source and cesium metal atoms, and the PLL circuit has an oscillation frequency higher than that of a conventional oscillator. Since an oscillator that oscillates at a frequency as low as 1 / n is used, it is possible to provide an atomic oscillator that can reduce power consumption and reduce manufacturing costs.

  Application Example 7 An electronic apparatus according to this application example includes the atomic oscillator described in any one of the application examples described above.

  According to this application example, since an atomic oscillator that can reduce power consumption and suppress manufacturing costs is provided, an electronic device that can reduce power consumption and suppress manufacturing costs is provided. be able to.

  Application Example 8 A moving object according to this application example includes the atomic oscillator described in any one of the above application examples.

  According to this application example, since an atomic oscillator that can reduce power consumption and suppress manufacturing costs is provided, a mobile body that can reduce power consumption and suppress manufacturing costs is provided. be able to.

  Application Example 9 A GPS (Global Positioning System) module according to this application example includes the atomic oscillator described in any one of the application examples.

  According to this application example, an atomic oscillator capable of reducing power consumption and manufacturing cost is provided, and thus a GPS module capable of reducing power consumption and manufacturing cost is provided. be able to.

The block diagram which shows the structure of the atomic oscillator which concerns on embodiment. Schematic which shows the structure of a quantum interference apparatus. The figure for demonstrating the energy state of the alkali metal in a gas cell. The graph which shows the relationship between the frequency difference of the two lights from a light source, and the detection intensity in a light detection part about a light source and a light detection part. The figure which shows the frequency characteristic output from a multiplier. The table | surface which shows the relationship between the difference of the output electric power output with the frequency of 1/2 of a predetermined frequency and a predetermined frequency, and frequency stability. The figure which shows the frequency characteristic of a filter part (notch filter). The figure which shows the frequency characteristic of the microwave output from a filter part. The block diagram which shows the structure of the atomic oscillator which concerns on a modification. The figure which shows the frequency characteristic of a filter part (band pass filter). The figure which shows the frequency characteristic of the microwave output from a filter part. The schematic block diagram which shows an example of the clock transmission system as an electronic device using the atomic oscillator of embodiment which concerns on this invention. The perspective view which shows the structure of a mobile body (automobile) provided with the atomic oscillator of embodiment which concerns on this invention. The figure which shows schematic structure at the time of using the electronic device of embodiment which concerns on this invention for the positioning system using a GPS satellite.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is different from the actual scale so that each layer and each member can be recognized.

<Atomic oscillator>
(Embodiment)
First, the principle of the atomic oscillator 3 will be briefly described with reference to FIGS.
FIG. 1 is a block diagram illustrating a configuration of an atomic oscillator according to the embodiment. The atomic oscillator 3 includes a quantum interference device 10 that outputs a difference between an atomic resonance frequency and an input microwave as a frequency error signal, and a voltage-controlled crystal oscillator (hereinafter, referred to as a frequency signal synchronized with the atomic resonance frequency). An oscillator (VCXO)) 5, a control signal corresponding to the frequency error signal, a frequency controller 4 for controlling the oscillator (VCXO) 5, and an output signal of the oscillator (VCXO) 5 as a reference signal. A PLL circuit 20 that oscillates by applying feedback control to the oscillator (VCO) 24 in the loop so that the phase difference from the output from the controlled oscillator (hereinafter referred to as an oscillator (VCO)) 24 is constant; A filter unit 30 for filtering the microwave output from the circuit 20 and an amplifier 6 for amplifying the output power output from the filter unit 30 And a bias circuit 8 to set the DC bias current applied to the quantum interference device 10.

  The PLL circuit 20 includes a 1 / R frequency divider 21 that divides the output frequency of the oscillator (VCXO) 5 into 1 / R, an oscillator (VCO) 24 that generates a frequency synchronized with the oscillator (VCXO) 5, an oscillator (VCO) 24 that multiplies the frequency output from 24, 1 / M prescaler 26 that divides the frequency output from multiplier 25 into 1 / M, and 1 / M prescaler 26 K / L frequency divider 27 that divides the frequency to be K / L, and phase comparator 22 that outputs the phase difference between the output of 1 / R frequency divider 21 and the output of K / L frequency divider 27. And an LPF 23 for extracting a direct current component based on the output of the phase comparator 22.

  FIG. 2 is a diagram illustrating a configuration of the quantum interference device. FIG. 3 is a diagram for explaining the energy state of the alkali metal in the gas cell of the quantum interference device shown in FIG. FIG. 4 shows the relationship between the frequency difference between two lights from the light emitting part (light source) and the detection intensity at the light detecting part in the light emitting part (light source) and the light detecting part of the atomic oscillator shown in FIG. It is a graph to show.

As shown in FIG. 2, the quantum interference device 10 includes a gas cell 11, a light emission unit 12 having a light source 13, and a light detection unit 14.
In the gas cell 11, gaseous cesium is enclosed as an example of an alkali metal (metal atom). As other alkali metals, rubidium, sodium and the like can be used. As shown in FIG. 3, the alkali metal has an energy level of a three-level system, and has three states of two ground states (ground states α and β) having different energy levels and an excited state. Can take. Here, the ground state α is a lower energy level than the ground state β. In the present embodiment, the optical components 15 and 16 are provided, but may be used if necessary.

  When two types of resonant light 1 and resonant light 2 having different frequencies are irradiated onto such a gaseous alkali metal, the difference (ω1-ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 Accordingly, the light absorptance (light transmittance) of the resonance light 1 and the resonance light 2 in the alkali metal changes. Then, when the difference (ω1−ω2) between the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 coincides with the frequency corresponding to the energy difference between the ground state α and the ground state β, the ground state α, and The excitation from the ground state β to the excited state stops. At this time, both the resonance light 1 and the resonance light 2 are transmitted without being absorbed by the alkali metal. Such a phenomenon is called a CPT (Coherent Population Trapping) phenomenon or an electromagnetically induced transparency (EIT) phenomenon.

  The light source 13 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above toward the gas cell 11. For example, the frequency ω1 of the resonant light 1 and the frequency ω2 of the resonant light 2 can be changed simultaneously by superimposing (modulating) a high-frequency signal on the bias current of the light source 13 and changing the frequency thereof. When the difference (ω1−ω2) between the frequency ω1 of the light 1 and the frequency ω2 of the resonant light 2 matches the frequency ω0 corresponding to the energy difference between the ground state α and the ground state β, the detection intensity of the light detection unit 14 is As shown in FIG. 4, it rises steeply. Such a steep signal is detected as an EIT signal. This EIT signal has an eigenvalue determined by the type of alkali metal. Therefore, an oscillator can be configured by using such an EIT signal.

Hereinafter, each part of the quantum interference device 10 will be sequentially described.
[Gas cell]
In the gas cell 11, gaseous cesium is enclosed as an alkali metal (metal atom). The gas cell 11 has a main body portion 17 having a columnar through-hole and a pair of windows 18 and 19 that block both openings of the through-hole. Thereby, the internal space in which the alkali metal is enclosed as described above is formed.

  Here, each window part 18 and 19 of the gas cell 11 has the permeability | transmittance with respect to the excitation light from the light source 13 mentioned above. The one window 18 transmits excitation light incident into the gas cell 11, and the other window 19 transmits excitation light emitted from the gas cell 11.

  The material constituting the windows 18 and 19 is not particularly limited as long as it has transparency to the excitation light as described above, and examples thereof include glass and quartz. The material constituting the main body portion 17 of the gas cell 11 is not particularly limited as long as it is other than a material that disturbs a magnetic field such as a magnetic material or a material that easily reacts with encapsulated metal atoms. It may be a material, a resin material, or the like, and may be a glass material, crystal, silicon, or the like, similarly to the windows 18 and 19. The window portions 18 and 19 are airtightly joined to the main body portion 17. Thereby, the internal space of the gas cell 11 can be made into an airtight space. The joining method of the main body 17 and the windows 18 and 19 of the gas cell 11 is determined according to these constituent materials, and is not particularly limited. For example, a joining method using an adhesive, a direct joining method, an anode A bonding method or the like can be used.

[Light emission part]
The light emitting unit 12 has a function of emitting excitation light that excites alkali metal atoms in the gas cell 11. More specifically, the light emitting unit 12 emits two types of light (resonant light 1 and resonant light 2) having different frequencies as described above. The frequency ω1 of the resonant light 1 can excite the alkali metal in the gas cell 11 from the ground state α to the excited state. Further, the frequency ω2 of the resonant light 2 can excite the alkali metal in the gas cell 11 from the ground state β described above to the excited state.

  The light source 13 is not particularly limited as long as it can emit the excitation light as described above. In the present embodiment, a vertical cavity surface emitting laser (VCSEL) which is a kind of semiconductor laser is used. Yes.

[Optical parts]
As shown in FIG. 2, the plurality of optical components 15 and 16 are respectively provided on the optical path a of the excitation light LL between the light emitting unit 12 (light source 13) and the gas cell 11 described above. In the present embodiment, the optical component 15 and the optical component 16 are arranged in this order from the light source 13 side to the gas cell 11 side.

  The optical component 15 is a λ / 4 wavelength plate. Thereby, the excitation light LL from the light source 13 can be converted from linearly polarized light into circularly polarized light (right circularly polarized light or left circularly polarized light).

  The optical component 16 is a neutral density filter (ND filter). Thereby, the intensity of the excitation light LL incident on the gas cell 11 can be adjusted (decreased). Therefore, even when the output of the light source 13 is large, the excitation light incident on the gas cell 11 can be set to a desired light amount. The intensity of the excitation light LL having polarization in a predetermined direction that has passed through the optical component 15 can be adjusted by the optical component 16.

  In addition to the wave plate and the neutral density filter, other optical components such as a lens and a polarizing plate may be disposed between the light source 13 and the gas cell 11. If adjustment (decrease) of the intensity of the excitation light from the light source 13 is unnecessary, the optical component 16 can be omitted.

[Photodetection section]
The light detection unit 14 has a function of detecting the intensity of the excitation light LL (resonance light 1 and resonance light 2) transmitted through the gas cell 11. The photodetector 14 is not particularly limited as long as it can detect the excitation light as described above. For example, a photodetector (light receiving element) such as a solar cell or a photodiode can be used.

Next, returning to FIG. 1, the oscillator (VCO) 24, the multiplier 25, and the filter unit 30 provided in the PLL circuit 20 will be described.
The PLL circuit 20 includes a multiplier 25 that multiplies the output of the oscillator (VCO) 24. The light source 13 (see FIG. 2) is obtained by multiplying the oscillation frequency oscillated by the oscillator (VCO) by n. A predetermined frequency for modulating the VCSEL is generated. As a result, an oscillator that oscillates at a frequency 1 / n lower than the predetermined frequency can be used as the oscillator (VCO) 24. In the present embodiment, cesium is used for the metal atom, and 4.5963 GHz (predetermined frequency) that is ½ of the transition frequency of cesium is generated by the PLL circuit 20.

  Since an oscillator capable of oscillating 4.5963 GHz has a high oscillation frequency, loss in a circuit element such as a transmission line is increased, and accordingly, the Q factor of the resonance circuit is deteriorated and output power is reduced. The decrease in output power needs to be compensated for by the amplifier 6 provided at the subsequent stage of the oscillator, which increases the power consumption. In addition, high-precision manufacturing / assembly / mounting technology is required to achieve desired characteristics, and the higher the frequency, the higher the procurement cost of the oscillator (VCO) 24. Furthermore, the oscillator (VCO) 24 capable of oscillating 4.5963 GHz has a small distribution amount in the market and contributes to an increase in cost. Therefore, in this embodiment, since the multiplier 25 uses a doubler (n = 2) multiplier, the oscillator (VCO) 24 oscillates 2.29816 GHz (1/2 of the predetermined frequency). An oscillator can be used. Thereby, the power consumption in the amplifier 6 and the procurement cost of the oscillator (VCO) 24 can be suppressed.

  Further, a filter that allows a predetermined frequency (4.5963 GHz) output from the multiplier 25 to pass between the PLL circuit 20 and the amplifier 6 and attenuates a frequency that is ½ of the predetermined frequency (2.29816 GHz). The unit 30 is connected. The filter unit 30 is preferably connected between the amplifier 6 and the multiplier 25, but may be connected to any location between the quantum interference device 10 and the multiplier 25. However, in the case where a filter unit is connected between the quantum interference device 10 and the bias circuit 8 that sets a DC bias current applied to the VISSEL as the light source 13 (see FIG. 2) provided in the quantum interference device 10. It is necessary to use a current-pass filter.

  FIG. 5 is a diagram illustrating the frequency characteristics output from the multiplier 25. The multiplier 25 doubles the oscillation frequency 2.29816 GHz of the oscillator (VCO) 24 to generate 4.5963 GHz (predetermined frequency) that is 1/2 of the transition frequency of cesium. However, a frequency component corresponding to m times 2.29816 GHz (m = 1, 2, 3,...) Is output from the multiplier 25 in addition to 4.5963 GHz. According to the oscillator (VCO) 24 and the multiplier 25 used in the present embodiment, the output power output at a half frequency (2.29816 GHz) of the predetermined frequency is output at the predetermined frequency (4.5963 GHz). Relative comparison with the output power is about -10 dB. Similarly, the output power output at a frequency 1.5 times the predetermined frequency (6.889448 GHz: 2.29816 GHz × 3) was about −15 dB.

  FIG. 6 is a table showing the relationship between the frequency stability and the difference between output powers output at a predetermined frequency and a frequency that is ½ of the predetermined frequency. The inventor has found through experiments that the frequency stability of the atomic oscillator 3 is reduced when a frequency that is ½ of the predetermined frequency is input to the quantum interference device 10. According to FIG. 6, the output power output at a predetermined frequency (4.5963 GHz) is 15 dB or more in relative comparison with the output power output at a frequency ½ (2.29816 GHz) of the predetermined frequency. It can be seen that a desired frequency stability can be obtained. Furthermore, it is desirable that it is 20 dB or more in which no deterioration in frequency stability is observed. Note that similar results were obtained in experiments at a predetermined frequency (4.5963 GHz) and 1.5 times the predetermined frequency (6.889448 GHz). From FIG. 6, an atomic oscillator having a desired frequency stability can be realized by attenuating the power output at a frequency of ½ of the predetermined frequency (2.29816 GHz) by 5 dB or more by the filter unit 30. .

FIG. 7 is a diagram illustrating frequency characteristics of the filter unit (notch filter).
As described above, the performance required for the filter unit 30 is that the frequency to pass is a predetermined frequency (4.5963 GHz) and the frequency to be attenuated is 1/2 of the predetermined frequency (2.29816 GHz). There is also a relatively low attenuation of 5 dB. Therefore, in the present embodiment, a notch filter (band rejection filter) that is the simplest configuration using the series resonance of the inductor L and the capacitor C is used for the filter unit 30. An inductor L and a capacitor C that cause resonance at 1/2 of a predetermined frequency (2.29816 GHz) are selected, and are connected in series between the transmission line and the ground. Since the impedance between the transmission line and the ground becomes low at the resonance frequency (1/2 of the predetermined frequency) between the inductor L and the capacitor C, as shown in FIG. 7, the frequency is 1/2 (2.29816 GHz). Thus, a frequency characteristic having an attenuation pole can be obtained. In addition, this embodiment is an example and is not limited to this. As a method of attenuating a half of the predetermined frequency, a high-pass filter configured using an inductor and a capacitor may be configured and connected.

  FIG. 8 is a diagram illustrating the frequency characteristics of the microwave output from the filter unit 30. By connecting the filter unit 30 having a notch filter between the multiplier 25 and the amplifier 6, as shown in FIG. 8, the output power output at a predetermined frequency (4.5963 GHz) is reduced to 1 / of the predetermined frequency. It can be set to 15 dB or more by relative comparison with output power output at a frequency of 2 (2.29816 GHz).

As described above, according to the atomic oscillator 3 according to this embodiment, the following effects can be obtained.
The atomic oscillator 3 includes a multiplier 25 that causes the PLL circuit 20 to multiply the oscillation frequency output from the oscillator (VCO) 24 by n. Thereby, since the power consumption in the amplifier 6 and the procurement cost of the oscillator (VCO) 24 can be suppressed, it is possible to provide the atomic oscillator 3 with reduced power consumption and reduced manufacturing cost. Further, since the filter unit 30 is connected between the quantum interference device 10 and the PLL circuit 20, the output power output at a predetermined frequency is ½ the predetermined frequency and 1.5 times the predetermined frequency. In comparison with the output power output at a frequency of 15 dB, it can be set to 15 dB or more. Thereby, the atomic oscillator 3 having desired frequency stability can be provided.

  Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below.

(Modification)
FIG. 9 is a block diagram illustrating a configuration of an atomic oscillator according to a modification.
In the above embodiment, as shown in FIG. 1, the filter unit 30 has been described as having a notch filter, but the present invention is not limited to this configuration. In the present modification, the filter unit 40 is provided with a bandpass filter.
Hereinafter, the atomic oscillator 50 according to the modification will be described. In addition, about the component same as embodiment, the same number is attached | subjected and the overlapping description is abbreviate | omitted.

  The output power output from the filter unit 40 at a predetermined frequency (4.5963 GHz) is 1/2 of the predetermined frequency (2.29816 GHz) and the output power output at 1.5 times the predetermined frequency (6.889448 GHz). And a relative value of 20 dB or more is desirable. In order to realize this characteristic, the filter unit 40 is allowed to pass a predetermined frequency, and output power that is output at a frequency that is ½ of the predetermined frequency is 10 dB or more and is output at a frequency that is 1.5 times the predetermined frequency. It is necessary to use a band pass filter that attenuates the output power of 5 dB or more. Therefore, in this modification, a ladder-type bandpass filter in which a plurality of resonators are connected in a ladder shape is used for the filter unit 40.

FIG. 10 is a diagram showing the frequency characteristics of the filter unit (bandpass filter) 40.
The filter unit 40 includes a band pass filter including a series arm resonator S1 and parallel arm resonators P1 and P2. By making the resonance frequency of the series arm resonator S1 and the anti-resonance frequency of the parallel arm resonators P1 and P2 substantially coincide with a predetermined frequency (4.5963 GHz), as shown in FIG. A frequency characteristic having attenuation poles at the antiresonance frequency of the arm resonator S1 and the resonance frequencies of the parallel arm resonators P1 and P2 is obtained. The series arm resonator S1 and the parallel arm resonators P1 and P2 include an acoustic wave resonator having a piezoelectric substrate and an IDT (Inter Digital transducer) electrode formed on the piezoelectric substrate, an upper electrode, and a lower electrode. And a piezoelectric thin film resonator having a piezoelectric thin film sandwiched between an upper electrode and a lower electrode can be used. Further, it may be integrated with the PLL circuit 20. Note that the number of resonators to be used and the connection method are merely examples, and the present invention is not limited thereto. Further, an LC filter, a cavity resonator filter, a helical filter, a dielectric filter, or the like may be connected to the filter unit 40.

  FIG. 11 is a diagram illustrating the frequency characteristics of the microwave output from the filter unit 40. By connecting a filter unit 40 having a bandpass filter between the multiplier 25 and the amplifier 6, as shown in FIG. 11, the output power output at a predetermined frequency (4.5963 GHz) is reduced to 1 of the predetermined frequency. / DB (2.29816 GHz) and a relative comparison with the output power output at 1.5 times the predetermined frequency (6.889448 GHz), it can be set to 20 dB or more.

As described above, according to the atomic oscillator 50 according to this modification, the following effects can be obtained.
The atomic oscillator 50 includes a multiplier 25 that causes the PLL circuit 20 to multiply the oscillation frequency output from the oscillator (VCO) 24 by n. Thereby, since the power consumption in the amplifier 6 and the procurement cost of the oscillator (VCO) 24 can be suppressed, it is possible to provide the atomic oscillator 50 with reduced power consumption and reduced manufacturing cost. Further, since the filter unit 40 is connected between the quantum interference device 10 and the PLL circuit 20, the output power output at a predetermined frequency is ½ the predetermined frequency and 1.5 times the predetermined frequency. It can be set to 20 dB or more by relative comparison with the output power output at a frequency of. Thereby, the atomic oscillator 50 excellent in frequency stability can be provided.

<Electronic equipment>
The atomic oscillator of the present invention as described above can be incorporated into various electronic devices. Such an electronic device including the atomic oscillator of the present invention has excellent reliability. Hereinafter, an example of an electronic apparatus including the atomic oscillator of the present invention will be described. In the following description, an example using the atomic oscillator 3 of the embodiment will be described.

  First, a clock transmission system using the atomic oscillator according to the present invention will be described with reference to FIG. FIG. 12 is a schematic configuration diagram showing an example of a clock transmission system using the atomic oscillator according to the present invention.

  A clock transmission system 500 shown in FIG. 12 matches the clocks of the devices in the time division multiplexing network, and has a redundant configuration of N (Normal) system and E (Emergency) system.

  The clock transmission system 500 includes a CSM (Clock Supply Module) 501 and an SDH (Synchronous Digital Hierarchy) device 502 of an A station (N system), and a clock supply device 503 and an SDH of an B station (E system). A device 504, a clock supply device 505 of the C station, and SDH devices 506 and 507 are provided. The clock supply device 501 has an atomic oscillator 3 and generates an N-system clock signal. The atomic oscillator 3 in the clock supply device 501 generates a clock signal in synchronism with a more accurate clock signal from master clocks 508 and 509 including an atomic oscillator using cesium.

  The SDH device 502 transmits and receives the main signal based on the clock signal from the clock supply device 501, superimposes the N-system clock signal on the main signal, and transmits it to the lower clock supply device 505. The clock supply device 503 includes an atomic oscillator 3 and generates an E-system clock signal. The atomic oscillator 3 in the clock supply device 503 generates a clock signal in synchronization with a clock signal with higher accuracy from master clocks 508 and 509 including an atomic oscillator using cesium.

  The SDH device 504 transmits and receives the main signal based on the clock signal from the clock supply device 503, superimposes the E-system clock signal on the main signal, and transmits it to the lower clock supply device 505. The clock supply device 505 receives the clock signal from the clock supply devices 501 and 503 and generates a clock signal in synchronization with the received clock signal.

  Here, the clock supply device 505 normally generates a clock signal in synchronization with the N-system clock signal from the clock supply device 501. When an abnormality occurs in the N system, the clock supply device 505 generates a clock signal in synchronization with the E system clock signal from the clock supply device 503. By switching from the N system to the E system in this way, stable clock supply can be ensured and the reliability of the clock path network can be improved. The SDH device 506 transmits and receives the main signal based on the clock signal from the clock supply device 505. Similarly, the SDH device 507 transmits and receives the main signal based on the clock signal from the clock supply device 505. As a result, the C station apparatus can be synchronized with the A station or B station apparatus.

<Moving object>
Moreover, the atomic oscillator according to the present invention as described above can be incorporated into various mobile objects. Such a moving body including the atomic oscillator of the present invention has excellent reliability. In the following description, an example using the atomic oscillator 3 of the embodiment will be described.

  Hereinafter, an example of the moving body according to the present invention will be described with reference to FIG. FIG. 13 is a perspective view showing a configuration of a moving object (automobile) including the atomic oscillator according to the present invention.

  A moving body 1500 shown in FIG. 13 has a vehicle body 1501 and four wheels 1502, and is configured to rotate the wheels 1502 by a power source (not shown) provided in the vehicle body 1501. In such a moving body 1500, the atomic oscillator 3 is built. Based on the oscillation signal from the atomic oscillator 3, for example, a control unit (not shown) controls driving of the power source.

<GPS module>
Moreover, the atomic oscillator according to the present invention as described above can be incorporated into a GPS module. A GPS module including such an atomic oscillator of the present invention has excellent reliability. In the following description, an example using the atomic oscillator 3 of the embodiment will be described.

  A positioning system using a GPS satellite using the atomic oscillator according to the present invention will be described with reference to FIG. FIG. 14 is a diagram showing a schematic configuration when the atomic oscillator according to the present invention is used in a positioning system using a GPS satellite.

  The positioning system 100 shown in FIG. 14 includes a GPS satellite 200, a GPS receiving device 300, and a base station device 400. The GPS satellite 200 transmits positioning information (GPS signal). The GPS receiver 300 receives the positioning information from the GPS satellite 200 with high accuracy via, for example, an antenna 301 installed at an electronic reference point (GPS continuous observation station), and the receiver 302 receives the positioning information. And a transmission device 304 that transmits positioning information via the antenna 303.

  Here, the receiving device 302 is an electronic device including a GPS module 310 having the atomic oscillator 3 according to the embodiment of the present invention described above as a reference frequency oscillation source and a receiving circuit (not shown). Such a receiving apparatus 302 has excellent reliability. In addition, the positioning information received by the receiving device 302 is transmitted by the transmitting device 304 in real time. Base station apparatus 400 includes a satellite receiver 402 that receives positioning information from GPS satellite 200 via antenna 401, and a base station receiver 404 that receives positioning information from GPS receiver 300 via antenna 403. With. In addition, although the GPS satellite system demonstrated as an example of a global navigation satellite system (GNSS), it is applicable also to other satellite systems, such as GLONASS (Global Navigation Satellite System) and Galileo. .

  Note that the electronic device or the moving body in which the atomic oscillator of the present invention is incorporated is not limited to the above-described one, and for example, a mobile phone, a digital still camera, an ink jet type ejection device (for example, an ink jet printer), a personal computer (a mobile personal computer) , Laptop personal computer), TV, video camera, video tape recorder, car navigation device, pager, electronic organizer (including communication function), electronic dictionary, calculator, electronic game device, word processor, workstation, video phone, TV monitor for crime prevention, electronic binoculars, POS terminal, medical equipment (for example, electronic thermometer, blood pressure monitor, blood glucose meter, electrocardiogram measuring device, ultrasonic diagnostic device, electronic endoscope), fish detector, various measuring devices, instruments ( For example, Two, aircraft, gauges of a ship), can be applied to a flight simulator or the like.

  As described above, the atomic oscillator, the electronic device, the mobile body, and the GPS module of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to these, and for example, the embodiments described above. The configuration of each part can be replaced with any configuration that exhibits the same function, and any configuration can be added. Moreover, you may make it this invention combine arbitrary structures of each embodiment mentioned above.

  DESCRIPTION OF SYMBOLS 3 ... Atomic oscillator, 4 ... Frequency controller, 5 ... Oscillator (VCXO), 6 ... Amplifier, 8 ... Bias circuit, 10 ... Quantum interference device, 11 ... Gas cell, 12 ... Light emission part, 13 ... Light source, 14 ... Light Detection unit, 15, 16 ... optical component, 17 ... main body, 18, 19 ... window, 20 ... PLL circuit, 24 ... oscillator (VCO), 25 ... multiplier, 30, 40 ... filter unit, 50 ... atomic oscillator , 100 ... Positioning system, 200 ... GPS satellite, 300 ... GPS receiver, 301 ... Antenna, 302 ... Receiver, 303 ... Antenna, 304 ... Transmitter, 310 ... GPS module, 400 ... Base station device, 401 ... Antenna, 402: Satellite receiver, 403 ... Antenna, 404 ... Base station receiver, 500 ... Clock transmission system, 501 ... Clock supply device, 502 ... SDH device, 503 Clock supply device, 504 ... SDH apparatus, 505 ... clock supply device, 506 and 507 ... SDH device, 508, 509 ... master clock, 1500 ... mobile.

Claims (9)

A quantum interference device;
A PLL circuit having an oscillator and a multiplier for multiplying the oscillation frequency output from the oscillator by n;
An atomic oscillator comprising: an amplifier.   A filter unit that passes a predetermined frequency output from the multiplier and attenuates a half of the predetermined frequency is connected between the PLL circuit and the quantum interference device. The atomic oscillator according to claim 1.   The output power output from the filter unit at the predetermined frequency is 15 dB or more in a relative comparison with the output power output at a frequency that is 1/2 the predetermined frequency and 1.5 times the predetermined frequency. The atomic oscillator according to claim 2. The quantum interference device includes:
Metal atoms,
A gas cell in which the metal atoms are enclosed;
A light source that emits light including a resonant light pair that generates an electromagnetically induced transmission phenomenon in the metal atom;
The atomic oscillator according to claim 1, further comprising: a light detection unit that detects the light that has passed through the metal atom.   The atomic oscillator according to claim 4, wherein the light source is a semiconductor laser.   The atomic oscillator according to claim 4, wherein the light source is a vertical cavity surface emitting laser, and the metal atom is cesium.   An electronic apparatus comprising the atomic oscillator according to any one of claims 1 to 6.   A moving body comprising the atomic oscillator according to any one of claims 1 to 6.   A GPS module comprising the atomic oscillator according to any one of claims 1 to 6.

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