JPH0417409A - Delay line device with tap for surface acoustic wave - Google Patents

Abstract

PURPOSE:To realize a delay characteristic with excellent linearity by devising a program delay circuit to make the delay of a differential amplifier constant even when any of current switches of plural differential amplifiers is selected. CONSTITUTION:When a transistor(TR) Q1 of a current switch 8, e.g. is selected by digital signals d1-dk of a control circuit 10, the TR Q1 is turned on and a current Iref of a common current source 9 is fed to TRs Q11, Q12 of a lst differential amplifier D1, then an input signal to input terminals 5a, 5b is outputted to a delay circuit G1, amplified by the amplifier D1 and outputted to a common output terminal. Even when any TR of the current switch 8 is selected, since the delay of the differential amplifier is constant and a fixed delay time is small, the linearity of the delay characteristic is excellent.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a surface acoustic wave tapped delay line device.

C. Summary of the Invention] The present invention relates to a surface acoustic wave tapped delay line device,
Its basic structure is that the first electrode consists of interdigital electrodes.
A surface acoustic wave tapped delay line having an electrode and a second electrode having taps arranged in phase inversion according to a required inversion code sequence, the first or second electrode having a surface acoustic wave tapped delay line;
A signal is input in which a part in which the carrier wave is binary phase modulated in a part of the inverted code series, a part in which the carrier wave is blocked, and a part in which the carrier wave is binary phase modulated in the other part of the inverted code series are arranged in sequence. to reduce noise caused by input signal leakage.

[Conventional technology]

A surface acoustic wave tamped delay line device, such as a square filter, is used, for example, to synchronize a spread spectrum receiver. As shown in FIG. 9, which shows the electrode arrangement, this type of mated filter has interdigitated electrodes on the surface acoustic wave (SAW) propagation medium, for example, for input t F
i (1) and taps (2) whose phase is inverted according to a required inversion code sequence are arranged, for example, an output electrode (3).
and a surface acoustic wave tapped delay line formed in an array.

The direction of the tap of the output electrode (3) is reversed by the symbol ■ or ○. And its input electrode (
1), binary phase keying (BPSK) corresponding to the inverted code sequence of the taps of the output electrode (3) as shown in FIG.
A signal is added so that the reciprocal of the bit frequency of the e code matches the propagation time of the SAW between adjacent tap centers. q, the input electrode (1) causes the above-mentioned B
The SAW generated by the PSK signal propagates to the left in FIG. When the phase coincides with the tap of the electrode (3), a peak a appears in the output waveform measured by this oscilloscope, as shown in FIG. The output signal at this time actually has a time delay corresponding to the 5AWO propagation speed.

Note that the BPSK signal of the input signal at this time is the output electrode (
The BPSK signal is selected to be the same as or longer than the code sequence in 3), and this BPSK signal is repeatedly and continuously supplied.

However, in such a configuration, leakage of the input signal applied to the human-powered electrode to the output electrode is unavoidable, and this occurs as noise in the output waveform, and this noise may be as high as the peak a mentioned above, or If it is larger than this, malfunction will occur.

In order to avoid such inconveniences, as shown in the waveform diagram in FIG. 12, a pause period τ of the required time during which no input signal is supplied for 5 times in the above-mentioned repeatedly input BPSK signal period is provided. . This rest interval τ is set.

It is known to extract the original output signal based on the SAW that arrives late so that it can be distinguished from noise due to signal leakage.

[Problem to be solved by the invention]

The present applicant previously proposed a chemical substance detection device or a surface wave propagation velocity measuring device in Japanese Patent Application No. 1-47908 or Japanese Patent Application No. 1-34089.

In these systems, for example, a plurality of delay lines with surface acoustic wave taps are arranged in parallel to enable, for example, the detection of two types of mixed gases or the accurate measurement of the surface wave propagation velocity of a piezoelectric substrate. ing. However, in this case, interference due to signal leakage between the surface acoustic wave tapped delay lines may pose a problem.

The present invention aims to solve such problems.

[Means for Solving the Problems] In the present invention, as shown in a plan view of an example in FIG.
and a second electrode (13) having taps (12) arranged to invert the phase in accordance with a required inversion code sequence, specifically a code sequence based on the maximum long period sequence based on code logic. It has an elastic wave tapped delay line (14), and the first
Alternatively, the second electrode (11) or (13), for example, the first electrode (11), is subjected to two-phase phase modulation of the carrier wave with a part of the above-mentioned inverted code series, as shown in an example waveform diagram in FIG. a paused portion (section) τ1 where the carrier wave is blocked, and a paused portion (section) τ where the carrier wave is blocked. and a portion (section) τ2 in which the carrier wave is subjected to binary phase modulation using the other portion of the inverted code sequence are inputted.

Further, in another aspect of the present invention, as shown in a cross-sectional view of an example in FIG. 3, first electrodes (11) each consisting of interdigital electrodes and the required Specifically, a tap (1
2) and a second electrode (13) of the surface acoustic wave tapped delay line (14). To,
The propagation path of the surface acoustic wave in the tap array part corresponding to a part of the inverted code series, for example, the -half part, and the propagation path of the surface acoustic wave in the tap array part corresponding to the other part, for example, the other part, are each made of different types of organic matter. A thin film (16) [6,), (16□)) is arranged, and a part of the above-mentioned inverted sign series, for example - A half portion (section) τ1 in which the carrier wave is two-phase phase modulated, and a portion (section) τ in which the carrier wave is blocked or stopped. and,
Inputting a signal in which the other part (section) τ2 of the above-mentioned inverted code series, for example, the part (section) τ2 in which the carrier wave is two-phase modulated in the other part, is sequentially arranged, surface elasticity due to the adsorption of chemical substances to each organic thin film (16) is input. Chemical substances are detected by detecting changes in the effective propagation velocity of waves.

In still another aspect of the present invention, as shown in FIG. 4, a plan view of an example thereof, a non-piezoelectric substrate (17) is provided with first electrodes (11) each comprising an interdigital electrode, and a required specific electrode. Similarly, taps (12
), and a surface acoustic wave tapped delay line (14) having a second electrode (13) arranged with a non-piezoelectric substrate (17 ) above 1st
The piezoelectric body to be measured (18) is brought into contact across the electrode (11) and the second electrode (13), and as described above, the first or second electrode (11) or (12), for example, the first electrode (1
1) A part (section) τ1 of the above-mentioned inverted code sequence, for example, a part (section) in which the carrier wave is binary phase modulated in the -half part, a section (section) τ0, in which the carrier wave is blocked or stopped, and other parts of the above-mentioned inverted code sequence, for example, The part where the carrier wave is two-phase phase modulated in the other part (
The piezoelectric body (
18) The surface wave propagation velocity is measured.

[Operation] As described above, according to the present invention, the inverted code sequence of 1 is divided into at least two parts, one part and the other part, in the surface acoustic wave tapped delay line (14), and these parts each have a carrier wave. A portion (section) τ in which τ is two-phase phase modulated, and a pause portion (section) τ in which a carrier wave is blocked between the two. Since the input signal is provided with , the same effect as when the pause section is provided between repeating parts of the same inverted code series as mentioned at the beginning, i.e., prevention of signal leakage between input and output electrodes. In particular, when this surface acoustic wave tapped delay line configuration is applied to the detection of chemical substances and the measurement of propagation velocity in the other inventions described above or still other inventions, With a surface acoustic wave tapped delay line, the above-mentioned patent application filed by the present applicant has been disclosed.
47908 or Japanese Patent Application No. 1-34089, the detection or measurement similar to the case of providing a plurality of delay lines with surface acoustic wave taps can be carried out reliably by avoiding the generation of noise due to signal leakage. Obtainable.

[Example] An example in which the present invention is applied to a chemical substance detection device will be described.

In this case, as shown in the plan view of one example in FIG.
The electrode (11) and a predetermined inversion code sequence, in the example shown,
A surface acoustic wave tapped delay line (14) having a second electrode (13) having an array of taps (12) whose phase is inverted according to ■○e○■O is provided. Then, the second electrode (13) according to this predetermined inversion code sequence is divided into two parts (13,), for example, into a negative half part and an allogeneic part, in this example, O○■ and ■■○. Different types of organic thin films (16,) and (16z) each adsorbing a different chemical substance on (132) are deposited on each 5AWO propagation path.

As these organic thin films (16,) and (16□), Langmuir-Prodgett films can be used, and examples thereof include fatty acids whose alkyl groups have 15 to 24 carbon atoms, methyl esters, and ethyl esters thereof. fatty acid esters, aliphatic amines in which the alkyl group has 15 to 24 carbon atoms, aliphatic alcohols in which the alkyl group has 15 to 24 carbon atoms, phospholipids such as phosphatidylcholine and phosphatidylethanolamine, and phospholipids in which the alkyl group has 15 to 24 carbon atoms. 2
4 dimethyl dialkylammonium chloride, etc. The alkyl group of each of the above film-forming molecules may contain an unsaturated bond.

On the other hand, chemical substances adsorbed to these organic films, that is, detectable chemical substances, include various organic substances such as alcohols, aldehydes, amides, amines, ethers, ketones, and carboxylic acids, and single element molecules such as halogen gas. Can be mentioned.

and the first or second electrode (11) or (13),
In the illustrated example, as shown in the waveform diagram of one example in FIG. A modulated first part (section) τ1 and a rest part (section) τ in which the carrier wave is blocked. and a portion (section) τ2 in which the carrier wave is subjected to binary phase modulation using the other portion of the inverted code sequence described above are connected to an input signal a (19) that receives a signal that is sequentially arranged.

This input signal source (19) is mainly a carrier signal generation circuit (with a variable frequency of several tens of MHz), for example, as shown in the block diagram of one example in FIG.
71), a mixing circuit (72), a several MFlz clock generation circuit (73), a code sequence generation circuit (74), an analog switch (75), and a frequency division circuit (76), A mixing circuit ( 72)
In this case, the clock generation circuit (
The pause period τ is determined by the frequency dividing circuit (76) based on the clock from 73). Analog switch (75) set to
The mixing circuit (72) is controlled by, and from its output terminal, for example, the required code sequence signal explained in FIG.
1 and τ2, and these are the rest periods τ. It is output as a signal array that is repeatedly arranged with the two sides in between. Therefore, this code sequence signal is supplied to the first electrode (11) of the surface acoustic wave tapped delay line (14).

Moreover, FIG. 7 shows another example of the input signal source (19),
In FIG. 7, parts corresponding to those in FIG. 6 are given the same reference numerals and redundant explanations are omitted, but in this example, the configuration is such that the clock generation circuit (73) in FIG. 6 is omitted. . That is, in this case, the clock is generated by frequency-dividing the carrier signal. At this time, the shape of the interdigital electrodes (13) is determined by the frequency division method. That is, for example, when dividing the frequency by 1/4, the distance between the centers of the taps is approximately four times the interdigital period, and when dividing the frequency by 1/8, the distance between the centers of the taps is approximately eight times.

Detection of chemical substances by this device is performed as follows. That is, assuming that the mass per unit area of each organic thin film is the same, when the output from the electrode (13) is observed with an oscilloscope (20), the carrier frequency f
8A, peaks a and a2 occur repeatedly due to the image portions I and 2 shown in FIG. 3 based on different code sequences of the electrode (13). Then, this device was attached to one organic thin film (16,), (16□
), the adsorption of this chemical substance changes the 5AWO propagation state. As shown in B or C, only one of the peaks a1 or a2 occurs repeatedly. And in this case, fo
Since fI and fo fz are proportional to the adsorbed mass, 2
Detection of species of chemicals can be performed.

In the illustrated example, two different types of organic thin films (16,) and (16□) are provided in two parts in which the electrode (13) corresponding to one inverted code series is vertically arranged. However, three or more types of chemical substances can be detected simultaneously by providing different chemical substance films in three or more parts.

Further, an example in which the present invention is used to detect the 5AWO propagation velocity will be described in detail with reference to FIGS. 4 and 5.

In the illustrated example, a first electrode (11) and a second electrode (13) are formed by interdigital electrodes on an insulating non-piezoelectric substrate (17) such as a common glass substrate.

The electrode (13) is formed, for example, with its - half I and other half ■ corresponding to one half and the other half of the required inverted code series of 1, respectively. When the pinch between each tap in H is set to 2:1, the phase of each tap (12) in - half I is a code arrangement of ■○■, and the code arrangement of ■■■■ee in the other half ■. be.

To measure the SAW propagation speed of the piezoelectric body (18), as shown in FIG.
In this way, the code array ■O■ and ■O
■ Pause interval τ between eO. to transmit the carrier signal to 2
A phase modulated signal is input to the input electrode (11). By doing this, the next operation will cause the board (18) to have 5A
It becomes possible to measure the WO propagation velocity.

In this way, from the signal source (19),
There is a pause interval τ between ○■ and ■■○. For example, the first electrode (11) transmits a signal obtained by two-phase phase modulating the carrier signal by providing a
Enter. In this way, at a certain frequency, Figure 8B
As shown in the figure, the peak a1 corresponding to ■○■ is the maximum. Let this frequency be fH. Here, d is the distance between tap centers in the left half, n is an even integer obtained by dividing d by the period of the finger electrode IDT, W is the electrode width of the IDT, ■ is the SAW speed at the free surface, and U is the distance under the metal electrode. SAW in
It's speed. At another frequency fL slightly lower than that, the peak a2 becomes maximum when the BPSK signal of ■■e coincides with the tap of ■■■■ee, as shown in FIG. 8C. This is the time. W and U can be eliminated from equations (1) and (2), and V=
...(3)n (2/
fH-1/fL). Since n is an integer from the electrode pattern, d can be measured precisely. Therefore, by measuring fn and fL with high precision using a frequency counter, the SAW speed can be measured non-destructively using equation (3).

Note that on each side of the device of the present invention described above, for convenience of explanation, the number of codes of the inverted code series, and therefore the second electrode (13
) is limited to a small number of taps, but in reality it reaches several tens or more.

〔Effect of the invention〕

According to the above-mentioned device of the present invention, one of the electrodes of the surface acoustic wave tapped delay line (14), for example, the first electrode (11), is provided with at least two determination code sequences of 1 in one part and the other part.
A pause portion (section) τ in which the carrier wave is blocked between the sections (sections) τ1 and τ2 in which the carrier wave is two-phase modulated by dividing the carrier wave into two sections. Since the input signal is provided with , the effect is the same as when the pause period is provided between the repeating parts of the same inverted code series as described at the beginning, i.e., between the picture electrodes (11) and (I3). In particular, when this surface acoustic wave tapped delay line configuration is used for detecting chemical substances and measuring propagation velocity, it is possible to prevent signal leakage of multiple chemical substances and to measure propagation velocity. The second electrode (13) is arranged vertically, that is, the tap arrangement portion corresponding to one inverted code series is divided into a plurality of parts, and the input signal is a pause between the divisions of this inverted code series. interval τ. Since each output from each detection unit is provided in each rest interval τ. By detecting this, it is possible to avoid the generation of noise due to mutual interference, as in the previous example, when multiple independent tapped delay lines are provided and each inverted code sequence is input independently to each delay line. In addition, in order to prevent this interference, it is possible to avoid the complicated switching means of switching the input signal to each delay line and outputting it, so it has many practical benefits such as simplifying the configuration. bring.

[Brief explanation of drawings]

FIG. 1 is a plan view of an example of a delay line device with a surface acoustic wave tap according to the present invention, FIG. 2 is a waveform diagram of an example of its input signal, and FIG. 3 is a plan view of an example of a delay line device with a surface acoustic wave tap according to the present invention. FIG. 4 is a sectional view of one example of a delay line device, and FIG. 4 is a plan view of another example of a delay line device with a surface acoustic wave tap according to the present invention.
The figure is a cross-sectional view of an example of a method for measuring the surface wave propagation velocity, Figures 6 and 7 are block diagrams of examples of signal sources, Figure 8 is a waveform diagram for explanation, and Figure 9 is a conventional Electrode arrangement diagram of the device, Figure 10 is an input signal waveform diagram, Figure 1
FIG. 1 is an output waveform diagram, and FIG. 12 is an input signal waveform diagram. (11) is the first electrode, (12) is the tap, (13) is the second electrode, (4) is the surface acoustic wave tapped delay line, (I
5) is a piezoelectric substrate, (16a) and (16b) are organic thin films, and (17) is a non-piezoelectric substrate.

Claims (3)

[Claims] 1. A surface acoustic wave tapped delay line comprising first electrodes each comprising interdigital electrodes and a second electrode comprising an array of taps whose phase is inverted according to a required inversion code sequence, The first or second electrode includes a part where the carrier wave is binary phase modulated with a part of the inverted code series, a part where the carrier wave is blocked, and a part where the carrier wave is binary phase modulated with the other part of the inverted code series. 1. A surface acoustic wave tapped delay line device, which inputs signals in which are sequentially arranged. 2. First electrodes each consisting of interdigital electrodes are disposed on a piezoelectric substrate.
a surface acoustic wave tapped delay line comprising an electrode and a second electrode having taps arranged in phase inversion according to a required inversion code sequence; Different types of organic thin films are formed on the propagation path of the surface acoustic waves in the tap arrangement part corresponding to a part of the inverted code series of the second electrode and the propagation path of the surface acoustic wave in the tap arrangement part corresponding to the other part, respectively. The first or second electrode is provided with a part in which the carrier wave is modulated in two-phase phase by a part of the inverted code series, a part in which the carrier wave is blocked, and a part in which the carrier wave is modulated in two-phase phase by the other part of the inverted code series. A surface that detects a chemical substance by inputting a signal in which the modulated portions and the modulated portions are sequentially arranged, and detecting a change in the effective propagation velocity of a surface acoustic wave due to adsorption of the chemical substance to each of the organic thin films. Delay line device with elastic wave tap. 3. A surface acoustic wave tapped delay comprising, on a non-piezoelectric substrate, first electrodes each consisting of interdigital electrodes, and a second electrode consisting of an array of taps whose phase is inverted according to a required inversion code sequence. A piezoelectric material having a surface wave propagation velocity to be measured is brought into contact with the first electrode and the second electrode on the non-piezoelectric substrate, and the reverse sign is attached to the first or second electrode. A part of the sequence in which the carrier wave is two-phase modulated, a part in which the carrier wave is blocked,
A surface acoustic wave tapped delay characterized in that the surface acoustic wave propagation velocity of the piezoelectric body is measured by inputting a signal in which a part in which the carrier wave is two-phase modulated in the other part of the inverted code series is sequentially arranged. line equipment.