JP4135575B2 - Surface acoustic wave device input / output switching device and measurement system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an input / output switching device and a measurement system for a spherical surface acoustic wave element, and more particularly to an input / output switching device for a surface acoustic wave element that can suppress attenuation of a surface acoustic wave that circulates and improve measurement sensitivity. It relates to a measurement system.
[0002]
[Prior art]
In recent years, a surface acoustic wave device including a pair of comb-shaped electrodes on the surface of a spherical member instead of a flat plate member is known (see, for example, Patent Document 1). In this type of surface acoustic wave element, the spherical member itself or the member of the spherical member and the comb-shaped electrode is formed of a piezoelectric material.
[0003]
For this reason, when a short-time high-frequency voltage is supplied to the comb-shaped electrode, such a surface acoustic wave device generates a surface acoustic wave along the direction perpendicular to the comb teeth of the comb-shaped electrode. When released, this surface acoustic wave is received by the comb-shaped electrode every time it circulates around the surface of the spherical member and is converted into a high-frequency voltage.
[0004]
That is, this type of surface acoustic wave element has a function of converting a high-frequency voltage supplied to a comb-shaped electrode into a surface acoustic wave using a piezoelectric material, and a surface acoustic wave received by the comb-shaped electrode every time it circulates. It has the function to convert to.
[0005]
The surface acoustic wave slightly changes in speed and the like depending on the surface state of the spherical member. Therefore, the change is accumulated as the number of turns increases. Therefore, the spherical surface acoustic wave element is a high-sensitivity sensor that measures the decay time, the circulation speed, etc. of the circulating surface acoustic wave after the surface acoustic wave is generated, and evaluates the surface state of the spherical member based on the measurement result. The use as is expected.
[0006]
[Patent Document 1]
International Publication Number WO / 4525
[0007]
[Problems to be solved by the invention]
However, the spherical surface acoustic wave element as described above is expected to be used as a high-sensitivity sensor, but has a problem that the measurement sensitivity such as the decay time is low because the circulating surface acoustic wave attenuates quickly.
[0008]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an input / output switching device and a measurement system for a surface acoustic wave element that can suppress the attenuation of surface acoustic waves that circulate and improve measurement sensitivity. To do.
[0009]
[Means for Solving the Problems]
The invention corresponding to claim 1 is a drive system circuit for inputting a drive signal to a spherical surface acoustic wave element, and a measurement system circuit for measuring a plurality of round reception signals output from the surface acoustic wave element. A surface acoustic wave element input / output switching device, wherein the driving system circuit and the matching section provided between the measurement system circuit and the surface acoustic wave element, and each round reception During the waiting period until the measurement is started during the signal output period, the matching section is in a state of parallel resonance when viewed from the surface acoustic wave element or (2n-1) λ / 4 (where n is a natural number) , Λ is a high impedance circuit in a state of a circular received signal), and a matching changing means for changing the configuration of the matching section, and an input / output switching device for a surface acoustic wave device comprising: It is.
[0010]
According to a second aspect of the present invention, there is provided a driving system circuit for inputting a driving signal to a spherical surface acoustic wave element, and a measurement for measuring a plurality of round reception signals output from the surface acoustic wave element. Waiting until the start of measurement in a period of outputting each loop reception signal and a matching circuit provided between the system circuit, the drive system circuit, the measurement system circuit, and the surface acoustic wave element A high impedance circuit in which the matching section is in a state of parallel resonance or (2n-1) λ / 4 (where n is a natural number and λ is the wavelength of a circular received signal) during the period, when viewed from the surface acoustic wave element A surface acoustic wave element measurement system comprising: a matching changing unit that changes the configuration of the matching section.
[0011]
Therefore, according to the first and second aspects of the present invention, during the standby period, the matching changing means is in a state of parallel resonance when the matching section is viewed from the surface acoustic wave element or (2n-1) λ / 4 (where n is The configuration of the matching section is changed so that the high-impedance circuit is in the state of a natural number, λ is the wavelength of the circular received signal.
[0012]
As a result, during this standby period, the energy of the surface acoustic wave that circulates around the surface acoustic wave element is not released as the circulation reception signal. Therefore, the attenuation of the surface acoustic wave that circulates can be suppressed according to the standby period, and the measurement sensitivity can be improved.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram showing the configuration of a surface acoustic wave element measurement system according to the first embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of this surface acoustic wave element, and FIG. It is a schematic diagram which shows the waveform of each signal used for a surface acoustic wave element.
[0014]
Here, as an example, when the frequency of the burst wave for driving is set to around 45 MHz, the measurement system uses a spherical surface acoustic wave element (BS) 10 as a matching coil as shown in FIG. Driven through a matching section 20 comprising L (1 to 2 μH), a matching capacitor C1 (several tens to several hundreds pF), and a fine adjustment trimmer capacitor C2 (several pF), a circuit obtained from the surface acoustic wave device 10 This is for measuring the received signal through the matching section 20.
[0015]
Here, the matching section 20 is a π filter in which the matching coil L is a series element and the capacitors C1 and C2 are parallel elements. The fine adjustment trimmer capacitor C2 is disposed on the surface acoustic wave element 10 side, The capacitor C1 is disposed on the side opposite to the fine adjustment trimmer capacitor C2. The terminals on the opposite side of L in each of the capacitors C1 and C2 are grounded. Further, the space between L and C1 is grounded via a high-frequency blocking coil RFC1 (100 μH), and a DC component of switching diodes (hereinafter referred to as switching PIN diodes) D1 to D3 flows.
[0016]
Specifically, the measurement system includes (a) a driving system circuit for connecting the driving burst wave signal source 30 and the matching section 20, and (b) a standby system circuit for matching a part of the matching section 20 (matching). Change means), (c) a measurement system circuit for connecting the matching section 20 and the measurement unit 40, and a timing controller 50 for selecting one of these system circuits.
[0017]
Here, (a) In the drive system circuit, the drive burst wave signal source 30 is a coaxial cable 31 (50Ω), a DC cut capacitor C3 (100 pF), and a forward switch PIN diode D1 (at forward voltage; high frequency) The signal is electrically connected between L and C1 of the matching section 20 via 1Ω or less). Further, a drive system selection signal from the timing controller 50 can be input to the switching PIN diode D1 via the forward current limiting resistor R1 (1 kΩ) and the high frequency blocking coil RFC2 (100 μH). Furthermore, between R1 and RFC2, it is grounded via a DC cut capacitor C5 (10 nF).
[0018]
That is, (a) the drive system circuit converts the drive burst wave signal from the drive burst wave signal source 30 into the coaxial cable 31, the DC cut capacitor C3, and the switch in response to the drive system selection signal (ON state) from the timing controller 50. The signal is input between L and C1 of the matching section 20 via the PIN diode D1.
[0019]
(B) In the standby circuit, a switching PIN diode D2 (in the forward voltage; 1Ω or less for high-frequency signals) and a DC cut capacitor C6 (10 nF) between L and C1 of the matching section 20 are provided in the reverse direction. Is grounded. A standby system selection signal from the timing controller 50 can be input to the anode of the switching PIN diode D2 via the forward current limiting resistor R2 (1 kΩ).
[0020]
In other words, (b) the standby circuit receives a high frequency signal between L and C1 of the matching section 20 via the switch PIN diode D2 and the DC cut capacitor C6 in response to a standby system selection signal (ON state) from the timing controller 50. To ground. This L. Due to the grounding between C1, the standby circuit changes the configuration of the matching section 20 (an equivalent circuit configuration without C1) so that the matching section 20 is a high impedance circuit in parallel resonance when viewed from the surface acoustic wave element 10. To change).
[0021]
(C) In the measurement system circuit, the measurement unit 40 includes a coaxial cable 41 (50Ω), a DC cut capacitor C4 (100 pF), and a forward switching PIN diode D3 (at forward voltage; 1Ω or less for a high-frequency signal) ) Is electrically connected between L and C1 of the matching section 20. In addition, a measurement system selection signal from the timing controller 50 can be input to the switching PIN diode D3 via a forward current limiting resistor R3 (1 kΩ) and a high-frequency blocking coil RFC3 (100 μH). Furthermore, between R3 and RFC3, it is grounded via a DC cut capacitor C7 (10 nF).
[0022]
That is, (c) the measurement system circuit uses the measurement system selection signal (ON state) from the timing controller 50 to convert each round received signal from between L and C1 of the matching section 20 to the switch PIN diode D3, the DC cut capacitor. The data is input to the measurement unit 40 via C4 and the coaxial cable 41.
[0023]
Next, the surface acoustic wave device 10, the matching section 20, the driving burst wave signal source 30, the measurement unit 40, and the timing controller 50 used in the above measurement system will be described.
[0024]
The surface acoustic wave device 10 is a well-known device as described above. For example, as shown in FIG. 2, the surface acoustic wave device 10 includes a pair of comb-shaped electrodes 12 and 13 facing each other on the surface of a spherical member 11 such as quartz.
[0025]
That is, as shown in FIG. 3, the surface acoustic wave device 10 has an electric signal (driving signal S) of a burst wave (or an impulse or the like) having a frequency of about several tens to several hundreds MHz. ₀ ) Is received by each of the comb-shaped electrodes 12 and 13, the surface acoustic wave SAW (Surface Acoustic Wave) is generated on the surface of the spherical member 11 by the piezoelectric material in contact with each of the comb-shaped electrodes 12 and 13. Each time the surface acoustic wave SAW that circulates passes through the comb electrodes 12 and 13, the voltage (circular received signal S) ₁ , S ₂ , ...).
[0026]
In the present embodiment, when the surface state of the spherical member 11 is evaluated, the decay time T is measured among the decay time and the rotation speed described above. Specifically, based on the decay time T measured from the spherical member 11 in the standard surface state and the decay time T ′ measured from the spherical member 11 in the surface state to be evaluated, the change ΔT (= | T−T ′ |) is calculated, and the surface state of the spherical member 11 is evaluated by, for example, an evaluation value (ΔT / T). However, when measuring the decay times T and T ′ that are the basis of the evaluation value (ΔT / T), it is necessary to make the waiting periods (between t2 and t3 in FIG. 4) described later the same.
[0027]
The matching section 20 has a drive signal S input from the drive system circuit. ₀ Are input to the surface acoustic wave element 10 and a plurality of round received signals S output from the surface acoustic wave element 10 are input. ₁ , S ₂ ,... For passing or blocking.
[0028]
Here, when the matching section 20 is grounded at high frequency between L and C1 through a standby circuit, the parallel circuit of L and C2 has a resonance frequency that is the same value or substantially the same value as the frequency of each round reception signal. It is configured to have a relationship of C2 << C1 so as to be an LC2 parallel resonant circuit having.
[0029]
The driving burst wave signal source 30 is based on the generation timing and the time width received from the timing controller 50, and the driving signal S consisting of a high frequency burst wave. ₀ Is output to the coaxial cable 31.
[0030]
The measurement unit 40 starts measurement in response to a trigger signal from the timing controller 50, and the loop reception signals Si,..., Sn received from the matching section 20 via the switch PIN diode D 3, the DC cut capacitor C 4 and the coaxial cable 41. It has a function to measure the decay time of.
[0031]
Note that, as described with reference to FIG. 3, the measurement unit 40 has an attenuation time T measured in advance from the spherical member 11 in the standard surface state and an attenuation time T ′ measured from the spherical member 11 in the surface state to be evaluated. And the function of calculating the change ΔT (= | T−T ′ |) of both decay times based on the above, and the function of evaluating the surface state of the spherical member 11 based on the evaluation value (ΔT / T), for example. May be.
[0032]
The timing controller 50 includes a driving signal S composed of a burst wave generated by the driving burst wave signal source 30. ₀ And a function for switching each system so as to select one of the (a) drive system, (b) standby system, and (c) measurement system of the measurement system. Have
[0033]
Here, (a) when the drive system is selected, the timing controller 50 performs a function of inputting a drive system selection signal (ON state) to the switching PIN diode D1 via R1 and RFC2.
[0034]
(B) When selecting a standby system, the timing controller 50 executes a function of inputting a standby system selection signal (ON state) to the switching PIN diode D2 via R2.
[0035]
Note that the standby system selection signal (ON state) is the drive signal S. ₀ It is not necessary to input to the switching PIN diode D2 immediately after the input of the ₁ And the circular received signal S near the noise level _i It is only necessary to input to D2 for an arbitrary period between.
[0036]
(C) When the measurement system is selected, the timing controller 50 inputs a trigger signal for starting measurement to the measurement unit 40 and sends the measurement system selection signal (ON state) to the switching PIN diode D3 via R3 and RFC3. Execute the input function.
[0037]
Next, the operation of the surface acoustic wave element measuring system configured as described above will be described with reference to the timing chart of FIG. 4 and the equivalent circuit diagrams of FIGS. 4A to 4C, each signal represents an on state as + 5V and an off state as −5V.
[0038]
Now, as shown at time t0 in FIGS. 4A to 4C, the timing controller 50 is in the off state (reverse voltage state) of the drive system selection signal, standby system selection signal, and measurement system selection signal. ). That is, at time t0, the measurement system is not in any of the driving state of the surface acoustic wave element 10, the standby state before measurement, and the measurement state.
[0039]
Subsequently, during the period from time t1 to time t2, the timing controller 50 turns on the drive selection signal and inputs it to the switching PIN diode D1 via R1 and RFC2. When this drive selection signal is received, the switching PIN diode D1 is in a substantially short-circuit state of about 1Ω or less in terms of high frequency, and the drive burst wave signal source 30 and the matching section 20 are high frequency as shown in an equivalent circuit in FIG. Connected. Therefore, the drive signal S output from the drive burst wave signal source 30 during the period of time t1 to t2. ₀ Is input to the surface acoustic wave device 10 through the matching section 20.
[0040]
The surface acoustic wave device 10 receives the drive signal S ₀ Is received by each of the comb-shaped electrodes 12, 13, a surface acoustic wave is generated on the surface of the spherical member 11 to circulate around the surface of the spherical member 11.
[0041]
The surface acoustic wave element 10 receives a circular received signal S from each comb-shaped electrode 12, 13 every time a circulating surface acoustic wave passes through each comb-shaped electrode 12, 13. ₁ , S ₂ , ... are generated.
[0042]
Next, at time t2, the timing controller 50 turns the drive system selection signal off while turning the standby system selection signal on.
[0043]
When the drive system selection signal is turned off, the switching PIN diode D1 is cut off to cut off the drive burst wave signal source 30 and the surface acoustic wave device 10 at high frequency.
[0044]
Since the switching PIN diode D2 is substantially short-circuited in terms of high frequency when the standby system selection signal is turned on, between the L and C1 of the matching section 20 via D2 and C6 as shown in an equivalent circuit in FIG. Grounded at high frequency.
[0045]
Due to the grounding between L and C1, the circuit configuration of the matching section 20 is changed so that the matching capacitor C1 does not exist at a high frequency and is in a state of parallel resonance of L · C2 when viewed from the surface acoustic wave device 10. The
[0046]
Therefore, after time t2, the matching section 20 outputs the circular reception signal S output from the surface acoustic wave element 10 and having a relatively higher strength than that near the noise level. ₁ , S ₂ , ..., S _i-1 Shut off. Note that the round reception signal is not limited to being cut off from the first round, but may be cut off from any kth round.
[0047]
Next, at time t3, the timing controller 50 turns off the standby system selection signal and inputs a trigger signal for starting measurement to the measurement unit 40 to turn on the measurement system selection signal.
[0048]
When the standby system selection signal is turned off, the switching PIN diode D2 is cut off, and the grounding between the L and C1 of the matching section 20 is interrupted. As shown in an equivalent circuit in FIG. insert.
[0049]
With the insertion of C1, the matching section 20 eliminates the LC2 parallel resonance state seen from the surface acoustic wave element 10, and passes each round reception signal output from the surface acoustic wave element 10.
[0050]
On the other hand, when the measurement system selection signal is turned on, the switching PIN diode D3 is substantially short-circuited at high frequencies. _i , ..., S _n ,... Are input to the measuring unit 40 via D3, C4 and the coaxial cable 41.
[0051]
Further, the measurement unit 40 starts measuring the round reception signal in response to a trigger signal for starting measurement.
[0052]
The measuring unit 40 receives the received round reception signal S. _i , ..., S _n , ... decay time is measured. As described above, the measurement unit 40 may calculate the change ΔT in the decay time and the evaluation value (ΔT / T) based on the measured decay time.
[0053]
Next, at time t4, the timing controller 50 turns off the measurement system selection signal, turns off the switching PIN diode D3, and ends the current measurement. In the measurement system, after time t4, all system selection signals are turned off, and the measurement system returns to the state at time t0.
[0054]
Hereinafter, the measurement system can repeat the above-described process from time t0 to t4 as desired by the operator, and appropriately calculate an arithmetic average of measurement results, changes, evaluation values, and the like.
[0055]
As described above, according to the present embodiment, the drive signal S ₀ Are input to the surface acoustic wave element 10 and then a plurality of circular received signals S output from the surface acoustic wave element 10. ₁ , S ₂ , ..., S _i-1 , Si,..., Sn,. ₁ , S ₂ , ...), S _k , ..., S _i-1 Based on the standby system selection signal from the timing controller 50, the standby system circuit grounds the L and C1 of the matching section 20 at a high frequency.
[0056]
Along with this, the matching section 20 receives the round reception signal (S ₁ , S ₂ , ...), S _k , ..., S _i-1 Shut off. During this standby period, the energy of the surface acoustic wave SAW that circulates the surface acoustic wave element 10 is not released as a circulation reception signal. Accordingly, the attenuation of the surface acoustic wave that circulates can be suppressed according to the standby period, and the attenuation time T or the number of laps can be extended, so that the measurement sensitivity of the attenuation characteristics can be improved.
[0057]
Supplementally, the matching section 20 is provided by L, C1, and C2 in order to match the input impedance R of the driving burst wave signal source 30 or the measuring unit 40, as shown in an equivalent circuit in FIG. The reason why the matching section 20 is provided is that the operating impedance of the surface acoustic wave device 10 is very high, and at present, there is no electronic component that can be directly connected to the driving burst wave signal source 30 and the measurement unit 40, and By suppressing energy loss. Specifically, the matching section (π matching circuit or the like) 20 is inserted between the driving burst wave signal source 30 and the measurement unit 40 and the surface acoustic wave device 10, so that the operating impedance of the surface acoustic wave device 10 is 50Ω. Alternatively, the impedance is converted to a low impedance in the vicinity thereof, impedance matching with each of the parts 10, 30, and 40 is performed, and a general-purpose electronic component can be directly connected to the switching part.
[0058]
Specifically, in order to increase the impedance as much as possible on the surface acoustic wave element 10 side, C2 is an electrode capacitance + stray capacitance, and in practice, tuning is performed only by L, and C1 is set to several tens to several hundreds pF. Yes. Here, when C1 is short-circuited and viewed from the surface acoustic wave element 10 side, a parallel resonance state of L · C2 is obtained, and the impedance becomes very high.
[0059]
If this high impedance is provided during the circulation of the surface acoustic wave, if the release of the electrical energy generated in the electrode by the circulating surface acoustic wave is suppressed, the attenuation of the surface acoustic wave is reduced, resulting in a longer decay time. (Or a faster loop speed, etc.) can be observed.
[0060]
Note that the reason why the measurement sensitivity increases when the decay time is extended is that, for example, the influence of the measurement error of the decay time decreases and the resolution due to the decay time increases. The reason why the measurement sensitivity increases when the circulation speed is increased (= maintenance or reduced) is also the same.
[0061]
(Second Embodiment)
FIG. 9 is an equivalent circuit diagram showing a matching section applied to the measurement system according to the second embodiment of the present invention and its peripheral configuration. The same parts as those in FIG. Omitted, here the differences are mainly described. In the following embodiments, the same description is omitted.
This embodiment is a modification of the first embodiment, and when the frequency of the circulating reception signal becomes high, it becomes difficult to create a lumped constant matching coil L. Therefore, instead of the matching coil L, a strip is used. A transmission member 60 that can be formed by a line, a coaxial pipe or the like is provided.
[0062]
Here, for example, as shown in FIG. 9, the transmission member 60 has an electrical transmission path length from the surface acoustic wave element 10 to the ground via the ground path of the capacitor C1 when the capacitor C1 is grounded. Is set to a length that makes (2n−1) λ / 4 (where n is a natural number and λ is the wavelength of the circular received signal). The transmission path length value (2n-1) λ / 4 may be any of λ / 4, 3λ / 4, 5λ / 4, 7λ / 4,.
[0063]
Further, when the capacitor C1 is not grounded, the transmission member 60 transmits the circular reception signal from the surface acoustic wave element 10 to the drive burst wave signal source 30 or the input impedance R of the measurement unit 40 as described above.
[0064]
Even in the configuration as described above, similarly to the first embodiment, during the standby period between the times t2 and t3, the impedance Z viewed from the surface acoustic wave element 10 side is set to ∞Ω, and the emission of each round received signal is suppressed. Therefore, the same effect as that of the first embodiment can be obtained.
[0065]
(Third embodiment)
FIG. 10 is an equivalent circuit diagram showing a matching section applied to the measurement system according to the third embodiment of the present invention and its peripheral configuration.
[0066]
This embodiment is a modification of the first embodiment. The configuration of the matching section 20 is modified, the matching capacitor C1 is omitted, and a secondary coil Lt is provided opposite to the matching coil L. One end of the coil Lt is grounded, and the other end is connected to the drive burst wave signal source 30 or the input impedance R of the measuring unit 40 via the switch SW. The matching coil L and the secondary coil Lt constitute a transformer. Further, the number of turns of the secondary coil Lt is much smaller than the number of turns of the matching coil L.
[0067]
According to the above configuration, the switch SW is turned off (opened) during the standby period to form a parallel resonant circuit of L and C2, and the impedance Z viewed from the surface acoustic wave element 10 side is ∞. Since the release of each round reception signal is suppressed as Ω, the same effect as that of the first embodiment can be obtained.
[0068]
(Fourth embodiment)
FIG. 11 is an equivalent circuit diagram showing a matching section applied to a measurement system according to the fourth embodiment of the present invention and its peripheral configuration.
[0069]
The present embodiment is a modification of the third embodiment, in which a tap t is provided instead of the secondary coil Lt, and the tap t is connected to the matching coil L.
[0070]
Even in the configuration as described above, the parallel resonance circuit by L and C2 is formed by turning off the switch SW during the standby period, so that the same effect as the effect of the third embodiment is obtained. Obtainable.
[0071]
(Fifth embodiment)
FIG. 12 is an equivalent circuit diagram showing a matching section applied to a measurement system according to the fifth embodiment of the present invention and its peripheral configuration.
[0072]
This embodiment is a modification in which the second embodiment is combined with the third embodiment. In the third embodiment, the transmission member 60 of the second embodiment is provided in place of the matching coil L. It is a thing.
[0073]
Even in the above-described configuration, the switch SW is turned off (opened) during the standby period, so that a high impedance state is formed by the transmission member 60. Thus, the effect is similar to the effects of the second and third embodiments. The effect of can be obtained.
[0074]
(Sixth embodiment)
FIG. 13 is an equivalent circuit diagram showing a matching section applied to a measurement system according to the sixth embodiment of the present invention and its peripheral configuration.
[0075]
The present embodiment is a modification in which the second embodiment is combined with the fourth embodiment. In the third embodiment, the transmission member 60 of the second embodiment is provided instead of the matching coil L. It is a thing.
[0076]
Even in the configuration as described above, since the high impedance state is formed by the transmission member 60 by turning off the switch SW during the standby period, the same effect as the effects of the second and fourth embodiments is formed. The effect of can be obtained.
[0077]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage.
Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
[0078]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an input / output switching device and a measurement system for a surface acoustic wave element that can suppress the attenuation of the circulating surface acoustic wave and improve the measurement sensitivity.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a surface acoustic wave element measurement system according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing a configuration of a surface acoustic wave element in the same embodiment.
FIG. 3 is a schematic diagram showing a waveform of each signal in the same embodiment.
FIG. 4 is a timing chart for explaining the operation in the same embodiment;
FIG. 5 is an equivalent circuit diagram for explaining an operation in the same embodiment;
FIG. 6 is an equivalent circuit diagram for explaining an operation in the same embodiment;
FIG. 7 is an equivalent circuit diagram for explaining an operation in the same embodiment;
FIG. 8 is an equivalent circuit diagram for explaining an operation in the same embodiment;
FIG. 9 is an equivalent circuit diagram showing a matching section and its peripheral configuration applied to a measurement system according to a second embodiment of the present invention.
FIG. 10 is an equivalent circuit diagram showing a matching section applied to a measurement system according to a third embodiment of the present invention and its peripheral configuration.
FIG. 11 is an equivalent circuit diagram showing a matching section applied to a measurement system according to a fourth embodiment of the present invention and its peripheral configuration.
FIG. 12 is an equivalent circuit diagram showing a matching section applied to a measurement system according to a fifth embodiment of the present invention and its peripheral configuration.
FIG. 13 is an equivalent circuit diagram showing a matching section applied to a measurement system according to a sixth embodiment of the present invention and its peripheral configuration.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Surface acoustic wave element, 11 ... Spherical member, 12, 13 ... Comb-shaped electrode, 20 ... Matching section, 30 ... Drive burst wave signal source, 40 ... Measurement part, 50 ... Timing controller, 60 ... Transmission member, C1-C7 ... capacitor, L, RFC, Lt ... coil, R ... resistor, D1-D3 ... diode.

Claims (2)

A surface elasticity capable of switching between a driving system circuit for inputting a driving signal to a spherical surface acoustic wave element and a measuring system circuit for measuring a plurality of circular reception signals output from the surface acoustic wave element. A wave element input / output switching device, the matching section provided between the drive system circuit and the measurement system circuit and the surface acoustic wave element,
Of the period of outputting each round reception signal, during the standby period until the measurement is started, the matching section is in a state of parallel resonance when viewed from the surface acoustic wave element or (2n-1) λ / 4 (however, , N is a natural number, and λ is a wavelength of the circular received signal), a matching changing means for changing the configuration of the matching section so as to be a high impedance circuit,
An input / output switching device for a surface acoustic wave device, comprising: A drive system circuit for inputting a drive signal to the spherical surface acoustic wave element;
A measurement system circuit for measuring a plurality of round reception signals output from the surface acoustic wave element;
A matching section provided between the drive system circuit and the measurement system circuit and the surface acoustic wave element;
Of the period of outputting each round reception signal, during the standby period until the measurement is started, the matching section is in a state of parallel resonance when viewed from the surface acoustic wave element or (2n-1) λ / 4 (however, , N is a natural number, and λ is a wavelength of the circular received signal), a matching changing means for changing the configuration of the matching section so as to be a high impedance circuit,
A surface acoustic wave device measurement system comprising:

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