JP2008245003A - Apparatus for driving and measuring at multiple frequencies for spherical surface acoustic wave element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for driving and measuring at a plurality of frequencies for a spherical surface acoustic wave (SAW) element, capable of driving and measuring at the plurality of frequencies in spite of a configuration using a single driving system circuit/measuring system circuit. <P>SOLUTION: According to a configuration for driving and measuring a spherical SAW element at a plurality of frequencies of the present invention, a multiplication circuit is effectively utilized to create a plurality of frequencies from a single frequency and a propagation change in the plurality of frequencies can be observed by measuring a phase difference/strength for each frequency. Therefore, driving and measuring can be performed at the plurality of frequencies in spite of a single driving system circuit/measuring system circuit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spherical surface acoustic wave element and a spherical surface acoustic wave element used in a multiple frequency driving measurement apparatus for the spherical surface acoustic wave element.

  In recent years, a spherical surface acoustic wave element is known in which interdigital electrodes are formed on the surface of a piezoelectric crystal substrate having a spherical shape instead of a flat plate shape (see, for example, Patent Document 1).

  In this spherical surface acoustic wave element, when a high-frequency burst signal is applied to the interdigital electrode as a drive signal, a surface acoustic wave (SAW) is excited from the interdigital electrode, and the surface acoustic wave is applied to the surface of the substrate. It circulates around the annular region in multiple layers.

  The speed at which the surface acoustic wave multi-circulates changes according to the state of the substrate surface. Similarly, the speed of the surface acoustic wave similarly changes depending on the adhesion of molecules to the substrate surface.

  For this reason, the spherical surface acoustic wave device can detect a reaction such as an environmental gas by forming a reaction film on the molecules attached to the annular region on the surface of the substrate or in the annular region.

  In addition, since a spherical surface acoustic wave element cannot use only a crystal surface with good temperature characteristics that is possible with a flat plate type surface acoustic wave element, it is driven and measured at multiple frequencies as a compensation method for temperature, pressure, etc. There is a case.

In addition, it has been proposed to use a double electrode in a surface acoustic wave element (see, for example, Patent Document 2).
International Publication No. 01/45255 Pamphlet JP 56-34217 A

However, when a spherical surface acoustic wave element is driven and measured at a plurality of frequencies, a drive system circuit that drives the frequency and a measurement system circuit that measures the frequency are required for each frequency to be used. It was necessary to prepare multiple measurement circuits.
For this reason, when the multi-frequency drive measurement device becomes large-scale, the drive system circuit / measurement system circuit uses a lot of analog parts, and thus there is a problem that the cost increases.

  Therefore, the present invention has been made to solve the above-described problems, and is a spherical elasticity that can be driven and measured at a plurality of frequencies while having a configuration using a single drive system circuit / measurement system circuit. An object of the present invention is to provide a multi-frequency driving measurement apparatus for a surface acoustic wave element.

The present invention as claimed in claim 1 divides the fundamental frequency and creates a desired constant multiple frequency with a multiplier and synthesizes each of the constant multiple frequencies with a mixer circuit to create a signal having a plurality of frequency components. A drive system circuit for exciting the plurality of frequency signals to the spherical surface acoustic wave element;
The multiple frequencies that circulate the spherical surface acoustic wave element are decomposed into their respective frequencies, the signal on the low frequency side is made a desired constant multiple frequency with a multiplier, and the constant multiple frequency and the signal on the high frequency side are multiplied together. A measurement system circuit that calculates the phase difference and intensity between the combined signal and the signal obtained by multiplying the phase of either one of the constant multiple frequency signal and the high frequency signal by 90 ° by reading calculation And a multi-frequency drive measuring device for a spherical surface acoustic wave element.

  A second aspect of the present invention is the multi-frequency drive measuring device for the spherical surface acoustic wave element according to the first aspect, wherein the multiplier is a circuit for multiplying the frequency by an odd number multiple. This is a multi-frequency driving measurement device for a spherical surface acoustic wave element.

  The present invention according to claim 3 is a spherical surface acoustic wave element capable of exciting a plurality of frequencies, comprising at least an interdigital electrode as an excitation electrode, wherein the interdigital electrode is a double electrode. A spherical surface acoustic wave element.

  According to the configuration of the multi-frequency driving measurement device for the spherical surface acoustic wave element of the present invention, by using a multiplier, a plurality of frequencies are created from a single frequency, and the propagation change of the plurality of frequencies is changed to a frequency. It can be observed by measuring the phase difference / intensity of each. For this reason, it is possible to drive and measure at a plurality of frequencies while using a single drive system circuit / measurement system circuit.

The multi-frequency drive measuring device of the spherical surface acoustic wave element of the present invention,
Divide the fundamental frequency and create a desired constant frequency with a constant frequency circuit, combine the constant frequency with a mixer circuit to create multiple frequencies, and excite the multiple frequencies to the spherical surface acoustic wave device Drive system circuit
Multiple frequencies that circulate the spherical surface acoustic wave element are decomposed into their respective frequencies, the signal on the low frequency side is made the desired fixed frequency with a fixed frequency circuit, and the fixed frequency and high frequency are changed without changing the phase. The phase difference and intensity between the signal obtained by multiplying the signals on the side and the signal obtained by multiplying the phase of either the fixed frequency or the high frequency signal by 90 ° are read operations. Measurement system circuit to calculate
It is provided with.

At this time, the multiplier is preferably a circuit that multiplies the frequency by an odd number multiple.
By multiplying the frequency by an odd number times, the structure of the interdigital electrode, which is the excitation portion of the surface acoustic wave, can be made a double electrode.

Further, in the spherical surface acoustic wave element used in the spherical surface acoustic wave element multi-frequency drive measuring apparatus of the present invention, the interdigital electrode as the excitation electrode is preferably a double electrode.
In addition to the advantage of a simple structure, the double electrode can suppress the reflection of surface acoustic waves in the electrode as much as possible. Moreover, a plurality of frequencies can be excited by setting the frequency to an odd multiple of that of the electrode structure.

  The spherical surface acoustic wave element multi-frequency drive measuring apparatus of the present invention can drive a spherical surface acoustic wave element capable of exciting multiple frequencies with only a single frequency and extract only the phase difference at high speed. For this reason, it is possible to drive and measure at a plurality of frequencies while using a single drive system circuit / measurement system circuit.

  Hereinafter, the multi-frequency drive measuring apparatus for the spherical surface acoustic wave element of the present invention will be described with reference to FIG. As a matter of course, the multi-frequency driving measurement apparatus for the spherical surface acoustic wave element of the present invention is not limited to the following configuration, and includes other configurations that can be analogized. Further, dimensions, drive frequency, and the like are not limited to the following descriptions, and can be appropriately designed according to specifications and the like.

  An example of the multi-frequency driving measurement apparatus of the present invention includes a spherical surface acoustic wave element 10, a transmission unit 201, a reception unit 202, a transmission / reception switching unit 203, and an impedance matching circuit 204.

The spherical surface acoustic wave element 10 has a propagation surface 11 and includes a spherical member 12 and a comb-shaped double electrode 13.
The propagation surface 11 has an annular surface made of a continuous curved surface, and surface acoustic waves (SAW) propagating in opposite directions excited by the interdigital double electrode 13 are formed on at least a part of the annular surface. Is provided with a circulation path for the circuit. The spherical member 12 is a three-dimensional substrate having a propagation surface 11 on which a once-excited surface acoustic wave can circulate, and in this embodiment, a single crystal crystal material processed into a spherical shape having a diameter of 10 mm is used for propagation. A Z-axis cinder is used as the surface.

  The transmission unit 201 is a circuit that generates a frequency that is a constant multiple of the fundamental frequency. The transmission unit 201 applies a high frequency burst from the fundamental frequency burst input unit 205 and divides the frequency into two by a distributor 211. Pass through. The other distributed high frequency is multiplied by a constant by an amplifier 214 by a multiplier 215, passes through a band pass filter, and is coupled by a frequency coupler 213.

  The burst signal including the combined two frequency components is sent to the impedance matching circuit 204 by the transmission / reception switch 203. The transmission / reception switch may be a unidirectional coupler, a field effect transistor, or a diode switch.

  The impedance matching circuit 204 is a parallel resonant circuit in which a coil and a capacitor are connected in parallel, and performs impedance matching between the transmitting unit 201 and the receiving unit 202 and the spherical surface acoustic wave element 10 while having frequency selectivity.

  The multi-round signal of the spherical surface acoustic wave element 10 passes through the impedance matching circuit 204 again and is sent to the receiving unit 202 by the transmission / reception switch 203.

The receiving unit 202 is separated by the frequency distributor 212 into a frequency that is a constant multiplied by the fundamental frequency. The fundamental frequency signal passes through the amplifier 214, passes through the multiplier 215, the band pass filter 216, and the amplifier 214. On the other hand, the signal multiplied by a constant passes through the amplifier 214, the band pass filter, and the amplifier 214.
At this time, the frequency of the two signals, that is, the fundamental frequency that has passed through the multiplier and the frequency multiplied by a constant, is the same. One of the signals is multiplied by 0 ° and 90 ° phase modulation by the phase modulator 217 and the mixer 219, and digitally converted by the analog-to-digital converter, and a signal (I) obtained by multiplying the frequencies obtained without changing the phase. ) And the signal (Q) data obtained by rotating the phase of one of the high frequencies by 90 ° and multiplying them.

  By dividing Q by I and calculating the arc tangent, the phase difference when the spherical surface acoustic wave element is excited at a plurality of frequencies is calculated.

  In FIG. 2, as an example, a spherical surface acoustic wave element is driven with a fundamental frequency of 15 MHz, a multiplier constant of 3 times, 15 MHz and 45 MHz as two frequencies, and a round received signal is measured. The schematic circuit diagram which shows the structure of the multiple frequency drive measurement apparatus of a surface acoustic wave element is shown.

1 is a schematic diagram showing a configuration of a spherical surface acoustic wave element of the present invention. It is a schematic circuit diagram which shows the structure of the multiple frequency drive measurement apparatus of the spherical surface acoustic wave element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Spherical surface acoustic wave element 11 ... Propagation surface 12 ... Spherical member 13 ... Interdigital double electrode 201 ... Transmission part 202 ... Reception part 203 ... Transmission / reception switching device 204 ... Impedance matching circuit 205 ... Fundamental frequency burst input part 211 ... Distributor 212 ... Frequency divider 213 ... Frequency coupler 214 ... Amplifier 215 ... Multiplier 216 ... Band pass filter 217 ... Phase modulator 218 ... 90 [deg.] Phase modulator 219 ... Mixer 220 ... Analog to digital converter

Claims (3)

Divide the fundamental frequency and make one constant multiplier frequency with a multiplier, synthesize the constant multiple frequencies with a mixer circuit to create a signal with multiple frequency components. A drive system circuit for exciting the wave element;
The multiple frequencies that circulate the spherical surface acoustic wave element are decomposed into their respective frequencies, the signal on the low frequency side is made a desired constant multiple frequency with a multiplier, and the constant multiple frequency and the signal on the high frequency side are multiplied together. A measurement system circuit that calculates the phase difference and intensity between the combined signal and the signal obtained by multiplying the phase of either one of the constant multiple frequency signal and the high frequency signal by 90 ° by reading calculation When,
A multi-frequency drive measuring device for a spherical surface acoustic wave element, comprising: A multi-frequency drive measuring device for a spherical surface acoustic wave device according to claim 1,
The multiplier is a circuit for multiplying the frequency by a constant number to an odd multiple, and is a multi-frequency drive measuring device for a spherical surface acoustic wave element. A spherical surface acoustic wave element capable of exciting a plurality of frequencies,
At least, an interdigital electrode that is an excitation electrode,
The interdigital electrode is a double electrode, and is a spherical surface acoustic wave device.