JP5973949B2 - Magnetic tuning device driving apparatus, signal analysis apparatus using the same, and magnetic tuning device driving method - Google Patents

Description

  The present invention relates to a magnetic tuning device driving apparatus, a signal analysis apparatus using the same, and a magnetic tuning device driving method.

  Conventionally, as a device that outputs a high-frequency signal of several GHz or more, a unit called YTO (YIG Tuned Oscillator) using a YIG that can vary the frequency over a wide frequency range as a resonance element has been used.

  YIG is a compound of yttrium, iron, and garnet, and is a magnetic resonance element having a characteristic that the resonance frequency caused by electron spin changes linearly according to the strength of an applied magnetic field. YTO is a unit in which an oscillation circuit using YIG as a resonance element, a tuning coil for applying a magnetic field to YIG, and the like are housed in a case for magnetic shielding.

  And YTO can oscillate and output a signal with a frequency proportional to the supplied current within a specified frequency range by supplying current to the tuning coil from the outside. Used in containers.

  In general, YTO has a main coil for coarse adjustment of oscillation frequency and an FM coil for fine adjustment of oscillation frequency as tuning coils. The main coil has a large number of turns in order to increase the variable width of the oscillation frequency, and the FM coil has a structure in which the number of turns is reduced so that it can respond to PLL control at high speed. Therefore, the variable width of the oscillation frequency of the FM coil is smaller than the variable width of the main coil, and the variable sensitivity is also small.

  A conventional magnetic tuning device driving apparatus for driving YTO has a configuration as shown in FIG. 6 (see, for example, Patent Document 1). The conventional magnetic tuning device driving apparatus shown in FIG. 6 includes a YTO 30 having a main coil 31, an FM coil 32, and a YIG 33, a frequency adjustment circuit 50, and a frequency setting circuit 60.

Frequency adjusting circuit 50 is adapted to output signal So YTO30 _{(f o)} and the predetermined relationship with respect to the set frequency of YTO30 frequency _{f r} of the reference signal Sr _{(f r)} is input, shift with respect to the set frequency of the oscillation frequency _{f o} of YTO30 is used to adjust the current supplied to the FM coil 32 of YTO30 as zero.

  The frequency setting circuit 60 includes an offset voltage generating circuit 61, an amplifying unit 62, an adding circuit 63, and a main coil driving circuit 64.

  First, an input tune voltage Vi corresponding to the set frequency of the YTO 30 is supplied to the amplifying means 62, and a constant voltage value equal to the input tune voltage Vi when the set frequency of the YTO 30 is a predetermined frequency (for example, 2.4 GHz). Is supplied to the amplifying means 62.

  Further, the output tune voltage Vo output from the amplifying means 62 and the offset voltage Vf output from the offset voltage generating circuit 61 are added by the adding circuit 63, and the added voltage is voltage-current converted by the main coil driving circuit 64. , A current flows through the main coil 31 of the YTO 30.

7 shows an example of the oscillation frequency _{f o} of YTO30 obtained for the set frequency (solid line). If the setting frequency of YTO30 is 2.4GHz or less (i.e., when the input tune voltage Vi is the reference voltage Vr higher), the deviation is relatively small with respect to the set frequency of the oscillation frequency _{f o} of YTO30. In this case, the input tune voltage Vi is inverted and amplified at a relatively low amplification rate by the amplification means 62 and supplied to the main coil 31.

On the other hand, if the set frequency of YTO30 is higher than the 2.4GHz (i.e., when the input tune voltage Vi is lower than the reference voltage Vr) according to the deviation with respect to the set frequency of the oscillation frequency _{f o} of YTO30 is higher setting frequency growing. In this case, the input tune voltage Vi is inverted and amplified at a relatively high amplification rate by the amplification means 62 and supplied to the main coil 31.

  In other words, the conventional magnetic tuning device driving apparatus configured as described above improves the tuning characteristics of the YTO 30 by changing the amplification factor of the amplification means 62 in accordance with the set frequency of the YTO 30.

Utility Model Registration No. 2541594

  However, the configuration disclosed in Patent Document 1 changes the amplification factor of the amplification means at a predetermined frequency, and there is a problem that individual variations cannot be compensated for YTOs having different tuning characteristics. It was. Further, Patent Document 1 neither describes nor suggests performing frequency sweeping with an FM coil.

  The present invention has been made to solve such a conventional problem, and is a frequency range in the case where a frequency tuning is performed at a high speed by an FM coil with respect to a magnetic tuning device having different tuning characteristics. The object of the present invention is to provide a magnetic tuning device driving apparatus, a signal analyzing apparatus using the same, and a magnetic tuning device driving method.

In order to solve the above problems, a magnetic tuning device driving apparatus according to claim 1 of the present invention is a magnetic tuning device driving apparatus for driving a magnetic tuning device having a main coil, a subcoil, and a magnetic resonance element, A main coil drive circuit that outputs a drive current to the main coil, a phase-locked oscillator that outputs a control signal for synchronizing the output signal of the magnetic resonance element with a predetermined reference signal, and the subcoil based on the control signal And a sub-coil driving circuit for outputting a driving current to the main coil and a tuning frequency of the magnetic tuning device for dividing the oscillation frequency range of the magnetic tuning device into a plurality of bands and calculating a tuning characteristic of the magnetic tuning device with respect to the driving current of the main coil for each band comprising a characteristic calculating section, and on the basis of the tuning characteristic to determine the setting value of the driving current of the main coil for each of the band driving current value determination unit, the setting The drive current of the main coil is controlled based on the value, and the reference signal for performing frequency sweep with the sub-coil based on one oscillation frequency included in the oscillation frequency range of the magnetic tuning device is the phase. and a further comprising Ru constitute a sweep control section capable of outputting the locked oscillator.

With this configuration, the oscillation frequency range of the magnetic tuning device is divided into a plurality of bands, and the tuning characteristics of the magnetic tuning device with respect to the driving current of the main coil are calculated for each band, and the driving current of the main coil is calculated based on the tuning characteristics. Since the set value is determined, it is possible to expand the frequency range in the case where high-speed frequency sweep is performed by the secondary coil with respect to the magnetic tuning devices having different tuning characteristics. Also, with this configuration, it is possible to perform a high-speed frequency sweep by the auxiliary coil.

The magnetic tuning device driving equipment according to claim 2 of the present invention, the main coil, the sub coil, and a magnetic tuning device driving apparatus for driving the magnetic tuning device having a magnetic resonance device, the drive current to the main coil A main coil drive circuit that outputs a signal, a phase-locked oscillator that outputs a control signal for synchronizing the output signal of the magnetic resonance element with a predetermined reference signal, and a drive current that is output to the sub-coil based on the control signal A sub-coil drive circuit that divides the oscillation frequency range of the magnetic tuning device into a plurality of bands, and a tuning characteristic calculation unit that calculates a tuning characteristic of the magnetic tuning device with respect to the driving current of the main coil for each band, A drive current value determining unit that determines a set value of the drive current of the main coil for each band based on the tuning characteristics, and oscillation of the magnetic tuning device An offset voltage generation circuit for outputting an offset voltage corresponding to one oscillation frequency included in the wave number range to the main coil drive circuit, and a sweep voltage for enabling frequency sweep based on the one oscillation frequency And a sweep voltage generation circuit for outputting the sweep voltage to the main coil drive circuit, and the sweep control unit, when performing frequency sweep by the sub-coil, the sweep voltage generation circuit is connected to the main coil It is the structure separated from a drive circuit.

With this configuration, the oscillation frequency range of the magnetic tuning device is divided into a plurality of bands, and the tuning characteristics of the magnetic tuning device with respect to the driving current of the main coil are calculated for each band, and the driving current of the main coil is calculated based on the tuning characteristics. Since the set value is determined, it is possible to expand the frequency range in the case where high-speed frequency sweep is performed by the secondary coil with respect to the magnetic tuning devices having different tuning characteristics. Further, with this configuration, the noise component generated from the sweep voltage generation circuit does not affect the magnetic tuning device, so that the phase noise can be improved.

In the magnetic tuning device driving apparatus according to claim 3 of the present invention, the driving current value determining unit sets a linear current value with respect to an oscillation frequency of the magnetic tuning device based on the tuning characteristics for each band. It has a configuration for setting values .

With this configuration, a tuning characteristic that closely approximates the tuning characteristic of an actual magnetic tuning device can be obtained, and a set value of the driving current of the main coil can be obtained based on the tuning characteristic.

According to a fourth aspect of the present invention, there is provided a signal analyzing apparatus including any one of the above-described magnetic tuning device driving apparatuses, wherein a local signal capable of frequency sweeping is generated and input by the magnetic tuning device. A frequency converter for supplying a signal to a mixer together with a signal and extracting a signal in a predetermined intermediate frequency band from the output of the mixer by a filter; and a signal component of a designated observation band among the input signals is the filter of the frequency converter The magnetic tuning device driving device that performs frequency sweep control of the local signal of the local signal generator and the output signal of the frequency converter are sampled and converted into a digital signal sequence so that the signal is output in time series An A / D converter and a signal sequence output from the A / D converter during the sweep of the local signal are stored, and a frequency vs. signal intensity spectrum is stored. It has a signal analyzer for determining the tram characteristics, a structure and a display unit for displaying the obtained spectrum characteristic waveform by the signal analyzer.

  With this configuration, since the magnetic tuning device driving apparatus is provided, not only the frequency sweep by the general main coil but also the high-speed and high-accuracy frequency sweep by the sub coil can be performed.

According to a fifth aspect of the present invention, there is provided a magnetic tuning device driving method that drives a magnetic tuning device having a main coil, a subcoil, and a magnetic resonance element by using any one of the magnetic tuning device driving apparatuses described above. A device driving method comprising: a band dividing step for dividing an oscillation frequency range of the magnetic tuning device into a plurality of bands; and a tuning characteristic for calculating a tuning characteristic of the magnetic tuning device with respect to a driving current of the main coil for each band. A calculation step and a drive current value determination step of determining a set value of the drive current of the main coil for each of the bands based on the tuning characteristics.

  With this configuration, the oscillation frequency range of the magnetic tuning device is divided into a plurality of bands, and the tuning characteristics of the magnetic tuning device with respect to the driving current of the main coil are calculated for each band, and the driving current of the main coil is calculated based on the tuning characteristics. Since the set value is determined, it is possible to expand the frequency range in the case where high-speed frequency sweep is performed by the secondary coil with respect to the magnetic tuning devices having different tuning characteristics.

  The present invention divides the oscillation frequency range of the magnetic tuning device into a plurality of bands, calculates the tuning characteristics of the magnetic tuning device with respect to the driving current of the main coil for each band, and calculates the driving current of the main coil based on the tuning characteristics. By determining the set value, a magnetic tuning device driving apparatus capable of expanding the frequency range in the case of performing a high-speed frequency sweep by a secondary coil for a magnetic tuning device having different tuning characteristics, and A signal analyzing apparatus and a magnetic tuning device driving method used are provided.

It is a block diagram which shows the structure of the magnetic tuning device drive device as the 1st Embodiment of this invention. It is a flowchart for demonstrating the process which the control part of the magnetic tuning device drive device as the 1st Embodiment of this invention performs. It is a flowchart for demonstrating in detail the process in the flowchart of FIG. It is a graph which shows an example of the tuning characteristic of YTO. It is a block diagram which shows the structure of the signal analyzer as the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the conventional magnetic tuning device drive device. It is a graph which shows an example of the oscillation frequency obtained with respect to a setting frequency in the conventional magnetic tuning device drive device.

  Embodiments of a magnetic tuning device driving apparatus, a signal analysis apparatus using the same, and a magnetic tuning device driving method according to the present invention will be described below with reference to the drawings.

(First embodiment)
First, the configuration of the magnetic tuning device driving apparatus 10 as the first embodiment of the present invention will be described.

  As shown in FIG. 1, the magnetic tuning device drive apparatus 10 of this embodiment drives YTO30 as a magnetic tuning device which has the main coil 31, the FM coil 32, and YIG33.

  The magnetic tuning device driving apparatus 10 includes a main coil driving circuit 11 that outputs a driving current to the main coil 31, a phase locked loop circuit 13 that outputs a control signal for synchronizing the output signal of the YIG 33 with a predetermined reference signal, An FM coil drive circuit 12 that outputs a drive current to the FM coil 32 based on a control signal output from the phase-locked loop circuit 13 and a control unit 14 that performs various controls are mainly provided.

The phase-locked loop circuit 13 includes an FM coil so that the frequency and phase of the input output signal So (f _o ) of the YTO 30 are equal to the frequency and phase of the reference signal Sr (f _r ) input from the control unit 14. The drive circuit 12 is controlled.

  The control unit 14 includes, for example, a CPU, a ROM, a RAM, and the like. By executing a predetermined program, the tuning characteristic calculation unit 15, the drive current value determination unit 16, and the sweep control unit 17 are implemented by software. Configure.

  The tuning characteristic calculation unit 15 divides the oscillation frequency range of the YTO 30 into a plurality of bands, and calculates the tuning characteristic (current characteristics of the oscillation frequency) of the YTO 30 with respect to the drive current of the main coil 31 for each band.

  The drive current value determination unit 16 determines a set value for the drive current of the main coil 31 for each band based on the tuning characteristic calculated by the tuning characteristic calculation unit 15.

The sweep control unit 17 controls the drive current of the main coil 31 based on the set value of the drive current of the main coil 31 for each band determined by the drive current value determination unit 16, and is included in the oscillation frequency range of the YTO 30. A reference signal Sr (f _r ) for performing frequency sweeping with an FM coil 32 based on an arbitrary oscillation frequency is output to the phase locked loop circuit 13.

The control unit 14, the offset frequency f _m which is designated by the operating unit (not _shown), the information of the sweep frequency range Delta] f _m are input. Control unit 14, the setting of the offset frequency f _m frequency - to output to the voltage conversion operation unit 18a, the setting of the sweep frequency range Delta] f _m frequency - and outputs the voltage conversion operation unit 18b.

Frequency - voltage conversion calculation unit 18a according tuning of YTO30 stored in the nonvolatile memory or the like (not shown), the setting of the offset frequency f _m which is outputted from the control unit 14 to the voltage Vs' corresponding to the offset frequency f _m It is supposed to convert.

Frequency - voltage conversion calculation unit 18b according tuning of YTO30 stored in the nonvolatile memory or the like (not shown), a voltage Vt corresponding settings sweep frequency range Delta] f _m outputted from the control unit 14 to the sweep frequency range Delta] f _m It is supposed to convert to '.

  The offset voltage generation circuit 19 amplifies the voltage Vs ′ output from the frequency-voltage conversion calculation unit 18a and outputs the amplified voltage Vs ′ to the addition circuit 22 as the offset voltage Vs. Thereby, the offset voltage Vs corresponding to an arbitrary oscillation frequency included in the oscillation frequency range of the YTO 30 can be output to the main coil drive circuit 11.

  In addition, the sweep voltage generation circuit 20 amplifies the voltage Vt ′ output from the frequency-voltage conversion calculation unit 18 b via the disconnect switch 21 and outputs the amplified voltage Vt ′ to the addition circuit 22 as the sweep voltage Vt. As a result, the sweep voltage Vt for enabling the frequency sweep based on the oscillation frequency corresponding to the offset voltage Vs output from the offset voltage generation circuit 19 can be output to the main coil drive circuit 11.

  Note that a low-pass filter that can vary the cutoff frequency may be used in place of the separation switch 21. In this case, when the frequency sweep is performed only by the FM coil 32, the band of the noise component generated from the sweep voltage generation circuit 20 can be limited by setting the cut-off frequency lower, and the influence on the phase noise of the YTO 30 Can be reduced.

  The adder circuit 22 adds the offset voltage Vs from the offset voltage generation circuit 19 and the sweep voltage Vt from the sweep voltage generation circuit 20 and outputs the result to the main coil drive circuit 11.

<Overview of operation>
Hereinafter, an outline of the frequency sweep performed by the magnetic tuning device driving apparatus 10 will be described. Depending on the frequency sweep range, there are the following two types of operation modes.

[Operation mode 1]: When the frequency sweep range is relatively narrow and the frequency range can be covered only by changing the drive current of the FM coil 32 while keeping the current of the main coil 31 constant (for example, from 8 GHz to 8.01 GHz) Frequency sweep)

First, the operating unit (not shown), the offset frequency setting of the offset frequency _{f m} and 8.005GHz is intermediate 8GHz and 8.01GHz are specified.

  Next, the sweep control unit 17 of the control unit 14 turns off the disconnect switch 21 to disconnect the sweep voltage generation circuit 20 from the main coil drive circuit 11. By doing so, the noise component generated from the sweep voltage generation circuit 20 does not affect the YTO 30, so that the phase noise can be improved.

Next, the sweep control unit 17 gives the reference signal Sr (f _r ) to the phase locked loop circuit 13 so that the YTO 30 oscillates at 8 GHz.

Next, the sweep controller 17, YTO30 is to be frequency sweep to 8.01GHz, will alter the reference frequency _{f r} of the reference signal Sr given to a phase locked loop circuit 13 _{(f r).} At this time, the FM coil 32 changes the oscillation frequency of the YTO 30 in a range from −0.005 GHz to +0.005 GHz. Thereby, since the frequency sweep can be performed only by the FM coil 32 without moving the main coil 31 having a large inductance, a high-speed frequency sweep can be realized.

[Operation mode 2]: When the frequency sweep range is relatively wide and the frequency range cannot be covered by the FM coil 32 alone (for example, when performing frequency sweep from 8 GHz to 10 GHz).

First, the operating unit (not shown), the offset frequency setting to 8GHz the offset frequency f _m is specified. Furthermore, the operating unit (not shown), the sweep frequency range setting to 2GHz sweep frequency range Delta] f _m is designated.

  Next, the sweep control unit 17 turns on the disconnect switch 21 to connect the sweep voltage generation circuit 20 to the main coil drive circuit 11.

Next, the sweep control unit 17 gives the reference signal Sr (f _r ) to the phase locked loop circuit 13 so that the YTO 30 oscillates at 8 GHz.

Next, the sweep control unit 17 operates the sweep voltage generation circuit 20 so that the frequency of the YTO 30 is swept to 10 GHz, and changes the reference frequency of the reference signal Sr (f _r ) given to the phase locked loop circuit 13. Go.

<Magnetic tuning device drive method>
Next, the magnetic tuning device driving method of this embodiment will be described. FIG. 2 is a flowchart of a magnetic tuning device driving program executed by the control unit 14 of the magnetic tuning device driving apparatus 10.

  First, in step S1, the control unit 14 initializes the value of the index n indicating the number of divisions in the oscillation frequency range of the YTO 30 to “1”.

  Next, in step S2, the control unit 14 divides all the oscillation frequency ranges of the YTO 30 into a plurality of N bands. This division may be uniform or non-uniform, and its fineness is arbitrary.

  Next, in step S3, the control unit 14 calculates the tuning characteristic (current characteristic of the oscillation frequency) of the YTO 30 with respect to the driving current of the main coil 31 for the nth band, and the calculated tuning characteristic is not shown in a non-volatile memory or the like. To store. The process of step S3 will be described later.

  Next, in step S4, the control unit 14 determines a set value for the drive current of the main coil 31 in the n-th band based on the tuning characteristic calculated in step S3. Furthermore, the control unit 14 stores the determined setting value in a non-illustrated nonvolatile memory or the like. The process of step S4 will be described later.

  Next, in step S5, the control unit 14 determines whether or not the index n is smaller than the division number N. Here, the value of N is set to 2 or more. When the value of the index n is smaller than the division number N, the control unit 14 increases the value of the index n by 1 in step S6, and then executes the process of step S3 again. On the other hand, when the value of the index n reaches the division number N, the control unit 14 executes the process of step S7.

  In step S7, the sweep control unit 17 of the control unit 14 performs main processing based on the set value of each band determined in step S4 according to the offset frequency setting and sweep frequency range setting specified by the operation unit (not shown). The drive current of the coil 31 and the FM coil 32 is controlled.

Specifically, the sweep controller 17, when the sweep frequency range Delta] f _m of been swept frequency range setting designated by the operating unit (not shown) is relatively narrow, as an off the disconnecting switch 21, setting of the offset frequency f _m Is output to the frequency-voltage conversion calculation unit 18a, and a reference signal Sr (f _r ) for performing frequency sweep by the FM coil 32 is output to the phase-locked loop circuit 13. This corresponds to the operation mode 1 described above.

On the other hand, the sweep controller 17, when the sweep frequency range Delta] f _m of a given sweep frequency range set by the operating unit (not shown) is relatively wide, as on the disconnecting switch 21, the offset frequency f _m and sweep frequency range Delta] f The setting of _m is output to the frequency-voltage conversion arithmetic units 18a and 18b, and the corresponding reference signal Sr (f _r ) is output to the phase locked loop circuit 13. This corresponds to the operation mode 2 described above.

  Note that the processing of steps S1 to S6 (determining the tuning characteristics in each of the divided frequency ranges) may be performed before shipment or may be performed every time before the sweep control of step S7. Alternatively, it may be performed at an arbitrary timing by the user.

<Process of Step S3>
Next, details of the process of step S3 in the flowchart of FIG. 2 will be described. FIG. 3 is a flowchart of processing executed by the tuning characteristic calculation unit 15 constituting the control unit 14. Here, it is assumed that the minimum frequency f ₁ of the nth band is 8 GHz and the maximum frequency f ₂ is 9 GHz.

  First, in step S31, the tuning characteristic calculation unit 15 reads an initial value of the YTO tuning characteristic stored in advance in a non-illustrated nonvolatile memory or the like. At this stage, since the tuning characteristic of the YTO 30 is unknown, an ideal tuning characteristic whose oscillation frequency is proportional to the drive current of the main coil 31 is used as an initial value.

Next, in step S32, the tuning characteristic calculation unit 15, the setting of the offset frequency _{f m} for oscillating YTO30 at any oscillation frequency between _f 1 ~f ₂ Frequency - Output voltage conversion operation unit 18a At the same time, the corresponding reference signal Sr (f _r ) is output to the phase locked loop circuit 13. The offset voltage generating circuit 19, the voltage Vs' corresponding to the offset frequency f _m is the frequency - input from the voltage conversion operation unit 18a.

In step S32, the tuning characteristic calculation unit 15, or the setting of the sweep frequency range Delta] f _m to zero, or to turn off the disconnecting switch 21. The values used in the frequency-voltage conversion calculation units 18a and 18b are the initial values of the YTO tuning characteristics read in step S31.

  Next, in step S33, the tuning characteristic calculation unit 15 acquires the value of the drive current of the FM coil 32. At this time, the YTO 30 oscillates at 8 GHz. If the actual tuning characteristics of the YTO 30 are not ideal, the phase-locked loop circuit 13 automatically adjusts the drive current of the FM coil 32 to a non-zero value. Has been.

  Next, in step S34, the tuning characteristic calculator 15 determines whether or not the driving current of the FM coil 32 has approached zero within a sufficient error range. When the drive current of the FM coil 32 has not approached zero in a sufficient error range, the tuning characteristic calculation unit 15 executes the process of step S35. On the other hand, when the drive current of the FM coil 32 approaches zero within a sufficient error range, the tuning characteristic calculation unit 15 executes the process of step S36.

Next, in step S35, the tuning characteristic calculation unit 15, so that the driving current of the FM coil 32 approaches zero with sufficient error range, frequency - After adjusting the settings of the offset frequency f _m applied to the voltage conversion operation unit 18a The processes of steps S33 and S34 are executed again.

Next, in step S36, the tuning characteristic calculation unit 15 causes the YTO 30 to oscillate at a desired oscillation frequency between f _{1 and} f ₂ with the drive current of the FM coil 32 approaching zero within a sufficient error range. The driving current of the main coil 31 necessary for the operation or the voltage Vs ′ to be applied to the offset voltage generation circuit 19 is calculated, and the calculated value is stored in a non-illustrated nonvolatile memory or the like.

  Here, an outline of a method for calculating the drive current of the main coil 31 will be described with reference to FIG. In FIG. 4A, the dotted line indicates an ideal YTO tuning characteristic with respect to the driving current of the main coil 31, and the solid line indicates an example of the actual tuning characteristic of the YTO 30 with respect to the driving current of the main coil 31.

At the stage of step S33 is first executed, for example, when the oscillation frequency of YTO30 is _f 1 of (= 8 GHz) is the main coil 31 a drive current _{I A} of the point A based on the tuning characteristics of an ideal YTO Given. At this time, the oscillation frequency of the YTO 30 when there is no frequency correction by the FM coil 32 is fB at point _B. That is, the synchronization deviation due to the main coil 31 is f ₁ −f _B , and the desired oscillation frequency f ₁ cannot be obtained only by the main coil 31.

Thereafter, the processing in steps S33~S35 are repeated, it is possible to oscillate only in YTO30 main coil 31 at an oscillation frequency _{f 1.} Drive current of the main coil 31 at this time is I _C, and the offset frequency f _m has a frequency f _C of the point C.

Thus, the tuning characteristic calculation unit 15 should provide the drive current I _{C to} be supplied to the main coil 31 or the offset voltage generation circuit 19 from the offset frequency f _m of the frequency f _C based on the ideal YTO tuning characteristic. The voltage Vs ′ can be calculated backward.

Next, in step S37, the tuning characteristic calculator 15 determines whether or not the calculation of the drive current (or drive voltage) to be applied to the main coil 31 has been completed for all measurement frequencies between the oscillation frequencies f _{1 and} f _2. Determine whether. When the calculation of the drive current (or drive voltage) of the main coil 31 is not completed for all measurement frequencies between the oscillation frequencies f _{1 and} f ₂ , the tuning characteristic calculation unit 15 performs steps S32 to S36. Run the process again.

For example, the tuning characteristic calculation unit 15 calculates the drive current to be applied to the main coil 31 or the voltage Vs ′ to be applied to the offset voltage generation circuit 19 for f ₂ (= 9 GHz) which is the maximum frequency of the nth band. When finished, the process of the flowchart of FIG.

<Process of step S4>
Next, details of the process of step S4 in the flowchart of FIG. 2 will be described. In order to cause the YTO 30 to oscillate with the drive current of the FM coil 32 substantially zero at all the measurement frequencies between the oscillation frequencies f _{1 and} f ₂ of the n-th band in the process of step S3 above, The drive current to be applied to 31 or the voltage Vs ′ to be applied to the offset voltage generation circuit 19 was obtained.

  The drive current value determination unit 16 obtains the slope and intercept of a straight line that approximates the relationship between the oscillation frequency of the YTO 30 and the voltage Vs ′ to be applied to the offset voltage generation circuit 19 for the nth band, for example, by the method of least squares. These obtained values are stored in a nonvolatile memory (not shown) or the like. Here, it is assumed that the voltage Vs ′ applied to the offset voltage generation circuit 19 is proportional to the oscillation frequency of the YTO 30.

Further, the drive current value determination section 16, if the frequency of the n-th band as the offset frequency f _m has been set in step S7, the frequency - voltage conversion operation portion 18a outputs a voltage Vs' on said approximate straight line Thus, the parameter of the frequency-voltage conversion calculation unit 18a is changed.

  By performing the processing in steps S3 and S4 for all the bands, as shown by a dotted line in FIG. 4B, it is possible to calculate a tuning characteristic that closely approximates the tuning characteristic of the actual YTO 30. Based on this tuning characteristic, the set value of the drive current of the main coil 31 can be obtained. As a result, a drive current linear to the oscillation frequency of the YTO 30 can be applied to the main coil 31 for each band.

  As for the frequency-voltage conversion calculation unit 18b, frequency-voltage conversion may be performed using a single slope value calculated as a linear approximation from the minimum frequency and the maximum frequency in the entire oscillation frequency range of the YTO 30. This is because the frequency-voltage conversion calculation unit 18b is used only when frequency sweeping is performed by the main coil 31, so that it is not necessary to finely correct the linearity like the frequency-voltage conversion calculation unit 18a.

<Example of expansion of sweepable width by FM coil>
An example of actual YTO30 characteristics is shown below.
-Linearity error of YTO30: ± 5 MHz (maximum)
・ Frequency variable by YTO30 FM coil 32: ± 50 MHz
-Tuning error other than YTO30 linearity: ± 35 MHz
(Breakdown: temperature drift ± 10 MHz, magnetic hysteresis ± 10 MHz, temperature drift of drive circuit ± 5 MHz, other design margin ± 10 MHz)

Therefore, conventionally, the range that can be used for frequency sweeping in the frequency variable range of the FM coil 32 is:
± 50 MHz- (± 5 MHz + ± 35 MHz) = ± 10 MHz
The frequency width was 20 MHz.

Assuming that the linearity error of the YTO 30 can be improved to ± 1 MHz by the magnetic tuning device driving method of the present invention, the range that can be used for the frequency sweep in the frequency variable range of the FM coil 32 is:
± 50 MHz- (± 1 MHz + ± 35 MHz) = ± 14 MHz
Thus, the frequency width can be expanded to 28 MHz.

  As described above, in the method of the present invention, the entire oscillation frequency range of the YTO 30 is divided into a plurality of bands, but this division may be uneven depending on the system conditions, and the fineness may be arbitrary. In general, finely dividing the oscillation frequency range increases the effect of correcting the tuning characteristics of the YTO oscillation frequency, but the time required for the tuning characteristics calculation unit 15 to acquire the tuning characteristics increases. For this reason, it is desirable that the number of divisions in the entire oscillation frequency range of the YTO 30 is set in consideration of the balance between them.

<Example of expanding the high-speed sweep width>
As described above, if the sweepable width by the FM coil 32 can be widened, the drive current of the main coil 31 is fixed, and the frequency sweep can be performed by changing only the drive current of the FM coil 32. The frequency range that can be performed can be expanded.

  For example, the inductance of the main coil 31 of YTO is generally several tens mH to several hundreds mH. On the other hand, the inductance of the FM coil 32 is about several μH to several tens μH. Here, let us consider a case where the main coil 31 has an inductance of 40 mH, the FM coil 32 has an inductance of 10 μH, and 25 MHz is swept in 10 μs.

When the frequency sweep is performed only by the main coil 31, the operation is as follows.
Only the main coil 31: (The sensitivity of the main coil 31 is 20 MHz / mA, and the inductance is 40 mH.)
When sweeping at a frequency width of 25 MHz at 10 μs, a current change of 1.25 mA occurs at 10 μs. At this time, the counter electromotive force generated in the main coil 31 by the inductance is 40 mH × (1.25 mA / 10 us) = 5V.

The frequency sweeping with only the FM coil 32 is as follows.
-FM coil 32 only: (The sensitivity of FM coil 32 is 400 kHz / mA, and the inductance is 10 μH.)
When sweeping with a frequency width of 25 MHz at 10 μs, a current change of 62.5 mA occurs at 10 μs. At this time, the counter electromotive force generated in the FM coil 32 due to the inductance is 10 μH × (62.5 mA / 10 μs) = 62.5 mV.

  Since the main coil drive circuit 11 and the FM coil drive circuit 12 must apply the above-described inductance to the main coil 31 and the FM coil 32 at the time of frequency sweep, respectively, the higher the frequency sweep, the higher the voltage. Is required.

  As described above, when performing a high-speed sweep with the main coil 31, a higher voltage than that of the FM coil 32 is required. Therefore, the sweep speed by the main coil 31 is limited by the output upper limit voltage of the main coil drive circuit 11 and the like. According to the present invention, the frequency width that can be swept with only the FM coil 32 can be expanded, and the frequency sweep can be performed at a higher speed with only the FM coil 32.

<Example of frequency width expansion that can be swept with low phase noise>
Usually, in the main coil 31 and the FM coil 32, a noise current due to noise generated from the circuits up to the preceding stage is added to a driving current that is originally desired. The noise current component flowing through these coils affects the oscillation frequency of the YTO 30 and deteriorates the phase noise of the YTO 30.

  For example, in the previous YTO example, the main coil 31 is 50 times more sensitive than the FM coil 32, so even if the noise current component of each coil is the same, the effect on the phase noise of the YTO 30 is 50 times different.

  The signal input to the main coil drive circuit 11 is the sum of two systems, up to the offset voltage generation circuit 19 and the sweep voltage generation circuit 20. The noise current component applied to the main coil 31 is the sum of the noise of the circuit up to the offset voltage generation circuit 19, the noise of the circuit up to the sweep voltage generation circuit 20, and the noise of the main coil drive circuit 11 itself. When the frequency sweep can be performed with only 32, the sweep voltage generation circuit 20 can be separated from the main coil drive circuit 11, so that the deterioration of the phase noise can be suppressed accordingly.

Current noise due to each path is, for example, as follows.
Current noise due to the route to the FM coil drive circuit 12:
The FM coil 32 generates a noise signal corresponding to a current noise density of 150 pA / √Hz at a frequency of 10 kHz. Current noise through a path to the offset voltage generation circuit 19:
The main coil 31 generates a noise signal corresponding to a current noise density of 0.4 pA / √Hz at a frequency of 10 kHz and current noise through a path to the sweep voltage generation circuit 20:
The main coil 31 generates a noise signal corresponding to a current noise density of 3.2 pA / √Hz at a frequency of 10 kHz. Current noise by the main coil drive circuit 11:
The main coil 31 generates a noise signal corresponding to a current noise density of 0.9 pA / √Hz at a frequency of 10 kHz.

The following equation is known for obtaining phase noise from current noise.

In Equation 1, K is YTO coil sensitivity, _{i n} represents the current noise density, _{f m} is the offset frequency.

  According to Equation 1, the phase noise due to the current noise of the FM coil 32 is −167.4 dBc / Hz. If the phase noise of the single YTO 30 is −105 dBc / Hz when the phase noise is 10 kHz offset, the phase noise due to the current noise of the FM coil 32 is significantly smaller than that of the YTO 30 alone, and the influence can be ignored.

The total current noise of the main coil 31 can be calculated as shown in Equation 2 when the sweep voltage generation circuit 20 is provided, and can be calculated as Equation 3 when the sweep voltage generation circuit 20 is not provided.

  From the results of Equations 2 and 3, the phase noise due to the current noise of the main coil 31 is −106.5 dBc / Hz when the sweep voltage generation circuit 20 is present, and −117 when the sweep voltage generation circuit 20 is disconnected. .1 dBc / Hz.

  The former phase noise is close to the original phase noise of YTO30 and degrades the total phase noise to -102.7 dBc / Hz. On the other hand, the latter phase noise is sufficiently lower than the original phase noise of YTO30, and the total phase noise is -104.7 dBc / Hz, so that the original phase noise of YTO30 is hardly deteriorated. The present invention can expand the frequency width that can be swept in such a low phase noise state.

  As described above, according to the present invention, the oscillation frequency range of the YTO 30 is divided into a plurality of bands, and the tuning characteristic of the YTO 30 is corrected in each band, thereby reducing the frequency error during tuning of the YTO 30. Can do.

  Further, according to the present invention, since the tuning deviation due to the main coil 31 can be reduced, the frequency range in which the tuning deviation must be compensated for using the FM coil 32 can be reduced. The frequency range that can be swept can be expanded. Further, when the frequency is changed only by the FM coil 32, the sweep voltage generation circuit 20 of the main coil drive circuit 11 can be disconnected, so that the phase noise can be improved.

(Second Embodiment)
Next, a signal analysis device 40 as a second embodiment of the present invention will be described with reference to the drawings. Note that the description of the same configuration and operation as in the first embodiment will be omitted as appropriate.

5, the signal analyzer 40 of the embodiment, provided to the mixer 42 along with the input signal S _IN by the local signal L capable frequency sweep generated by YTO30, a predetermined intermediate frequency from the output of the mixer 42 A frequency converter 41 that extracts a band signal M by a filter 43, the magnetic tuning device driving apparatus 10 of the first embodiment, and an A / A that samples the output signal of the frequency converter 41 and converts it into a digital signal sequence A D converter 44, a signal analysis unit 45 for storing a signal sequence Dm output from the A / D converter 44 during the frequency sweep of the local signal L, and obtaining a spectrum characteristic of frequency versus signal intensity, and a signal analysis unit 45 And a display unit 46 for displaying the waveform of the spectrum characteristic obtained in (1).

That is, the input signal S _IN is input to the mixer 42 of the frequency converter 41, a local signal L and mixing from YTO30, among the frequency components of the difference or sum (. Which the difference in the following description), a predetermined The intermediate frequency band signal component M is extracted by the filter 43.

Here, when the center frequency of the filter 43 is F _IF , the frequency of the local signal L is F _L, and mixing is performed with an upper heterodyne having a local frequency F _L higher than the frequency F _IN of the analysis target signal to be converted to the intermediate frequency band. Assuming
_{F L} -F _IF = F _IN
The relationship holds.

Here, for _example, the F IF = 8 GHz, if swept local frequency _{F L} from 8.1GHz to 9 GHz, a frequency _{F IN} of the analyzed signal will vary from 100MHz to 1 GHz. That is, the filter 43, signal components from 100MHz to 1GHz of the input signal _{S IN} is to be extracted in chronological order of frequency of its original.

  In addition, although the circuit example which performs frequency conversion once is shown here, in practice, frequency conversion processing (generally by a local signal of a fixed frequency) is performed a plurality of times in the frequency conversion unit 41, Converting to a lower frequency band.

YTO30, as described in the first embodiment can output the output signal So having a frequency corresponding to the setting of the offset frequency f _m and sweep frequency range Delta] f _m by sweep control section 17 (f _o) as the local signal L It is configured as follows. This frequency sweep of the local signal L is performed according to the setting of the offset frequency f _m and sweep frequency range Delta] f _m is inputted from the sweep controller 17. Furthermore, the sweep controller 17 is adapted to provide the frequency information f _o indicating the frequency of the local signal L to the signal analyzer 45.

  On the other hand, the signal M output from the frequency converter 41 is sampled by the A / D converter 44 at a predetermined sampling period (a frequency more than twice the upper limit of the pass band of the filter 43), and obtained by the sampling. A digital signal sequence Dm is input to the signal analysis unit 45.

  The signal analysis unit 45 receives the digital signal sequence Dm obtained by the frequency sweep and the frequency information f in association with each other, stores them in a memory (not shown), performs a designated band limiting process, etc. A characteristic of frequency versus signal intensity S (f), that is, a spectrum characteristic is obtained. The display unit 46 displays the waveform of the spectrum characteristic obtained by the signal analysis unit 45 on the screen.

  Since the signal analysis apparatus 40 of the present embodiment configured as described above includes the magnetic tuning device driving apparatus 10 of the first embodiment, not only the frequency sweep by the general main coil 31 but also the FM coil 32 can perform high-speed and high-accuracy frequency sweeping with reduced phase noise.

10 Magnetic Tuning Device Drive Device 11 Main Coil Drive Circuit (Main Coil Drive Circuit)
12 FM coil drive circuit (sub-coil drive circuit)
13 Phase-locked loop circuit (phase-locked oscillator)
DESCRIPTION OF SYMBOLS 14 Control part 15 Tuning characteristic calculation part 16 Drive current value determination part 17 Sweep control part 18a, 18b Frequency-voltage conversion calculating part 19 Offset voltage generation circuit 20 Sweep voltage generation circuit 21 Isolation switch 22 Addition circuit 30 YTO (magnetic tuning device)
31 Main coil (main coil)
32 FM coil (sub-coil)
33 YIG (magnetic resonance element)
40 Signal Analyzer 41 Frequency Converter 42 Mixer 43 Filter 44 A / D Converter 45 Signal Analyzer 46 Display Unit

Claims (5)

A magnetic tuning device driving apparatus (10) for driving a magnetic tuning device (30) having a main coil (31), a secondary coil (32), and a magnetic resonance element (33),
A main coil drive circuit (11) for outputting a drive current to the main coil;
A phase-locked oscillator (13) for outputting a control signal for synchronizing the output signal of the magnetic resonance element with a predetermined reference signal;
A sub-coil drive circuit (12) for outputting a drive current to the sub-coil based on the control signal;
A tuning characteristic calculation unit (15) that divides an oscillation frequency range of the magnetic tuning device into a plurality of bands, and calculates a tuning characteristic of the magnetic tuning device with respect to the driving current of the main coil for each band;
A drive current value determining unit (16) for determining a set value of the drive current of the main coil for each band based on the tuning characteristics ;
Based on the set value, the drive current of the main coil is controlled, and the reference signal for performing the frequency sweep with the sub coil based on one oscillation frequency included in the oscillation frequency range of the magnetic tuning device is magnetic tuning device driving apparatus further comprising wherein Rukoto the output can sweep controller to the phase lock oscillator (17). A magnetic tuning device driving apparatus (10) for driving a magnetic tuning device (30) having a main coil (31), a secondary coil (32), and a magnetic resonance element (33),
A main coil drive circuit (11) for outputting a drive current to the main coil;
A phase-locked oscillator (13) for outputting a control signal for synchronizing the output signal of the magnetic resonance element with a predetermined reference signal;
A sub-coil drive circuit (12) for outputting a drive current to the sub-coil based on the control signal;
A tuning characteristic calculation unit (15) that divides an oscillation frequency range of the magnetic tuning device into a plurality of bands, and calculates a tuning characteristic of the magnetic tuning device with respect to the driving current of the main coil for each band;
A drive current value determining unit (16) for determining a set value of the drive current of the main coil for each band based on the tuning characteristics;
An offset voltage generation circuit (19) for outputting an offset voltage corresponding to one oscillation frequency included in the oscillation frequency range of the magnetic tuning device to the main coil drive circuit;
A sweep voltage generating circuit (20) for generating a sweep voltage for enabling a frequency sweep based on the one oscillation frequency and outputting the sweep voltage to the main coil drive circuit;
When the frequency sweep is performed by the sub coil, the sweep control unit disconnects the sweep voltage generation circuit from the main coil drive circuit . 2. The drive current value determination unit sets a current value linear with respect to an oscillation frequency of the magnetic tuning device as the set value based on the tuning characteristic for each band. 3. A magnetic tuning device driving apparatus according to 2. A signal analyzer (40) comprising the magnetic tuning device driver (10) according to any one of claims 1-3.
A frequency at which a local signal capable of frequency sweep is generated by the magnetic tuning device (30) and applied to the mixer (42) together with the input signal, and a signal in a predetermined intermediate frequency band is extracted from the output of the mixer by the filter (43) A conversion unit (41);
The magnetic tuning device that performs frequency sweep control of a local signal of the local signal generator so that a signal component of a designated observation band of the input signal is output in time series from the filter of the frequency converter. A driving device;
An A / D converter (44) that samples the output signal of the frequency converter and converts it into a digital signal sequence;
A signal analysis unit (45) for storing a signal sequence output from the A / D converter during the sweep of the local signal and obtaining a spectrum characteristic of frequency versus signal intensity;
A signal analysis apparatus comprising: a display unit (46) for displaying a waveform of spectrum characteristics obtained by the signal analysis unit. A magnetic tuning device having a main coil (31), a subcoil (32), and a magnetic resonance element (33) using the magnetic tuning device driving apparatus (10) according to any one of claims 1 to 3. A magnetic tuning device driving method for driving a device (30) comprising:
A band dividing step of dividing the oscillation frequency range of the magnetic tuning device into a plurality of bands;
A tuning characteristic calculating step for calculating a tuning characteristic of the magnetic tuning device with respect to the driving current of the main coil for each band;
And a drive current value determining step for determining a set value of the drive current of the main coil for each of the bands based on the tuning characteristics.

Images