Three-time transition interference suppression method for surface acoustic wave device

Abstract

The invention relates to the field of surface acoustic wave device transition interference suppression, in particular to a three-time transition interference suppression method for a surface acoustic wave device, which comprises the following steps: acquiring geometric parameters for optimizing an interdigital transducer; adjusting the duration of an input excitation signal according to the geometric parameters of the optimized interdigital transducer, and carrying out time separation processing on a direct signal and a three-time transition signal; an output time window is obtained according to the duration of the input excitation signal, three-time transition signal shielding is carried out, a pure main signal is obtained and serves as a three-time transition interference suppression result, and triple transition echoes can be reduced to the maximum extent by finely optimizing IDT parameters, including careful design of the input excitation signal and selection of the output time window. Therefore, the separation of the main signal and the TTE echo in time is realized, and the measurement linearity and reliability in SAW sensing application are remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of transition interference suppression of surface acoustic wave devices, and in particular to a third-order transition interference suppression method for surface acoustic wave devices. Background Art

[0002] SAW delay line sensors also have some shortcomings that cannot be ignored. Among them, the nonlinear problem is more difficult. From the perspective of physical mechanism, the boundary conditions and structural factors of the substrate should not be underestimated. As the physical quantity changes, the reflection and scattering phenomena at the boundary tend to be complex, which in turn causes nonlinear problems. The second is the interference of the third-order transit signal (TTE). In the working process of the SAW delay line sensor, the third-order transit signal is a phenomenon that needs attention. When the surface acoustic wave propagates on the piezoelectric substrate, the ideal situation is that the surface acoustic wave propagates from the input transducer to the output transducer once to complete the signal conversion and detection. But in fact, due to the boundary conditions of the substrate and the propagation characteristics of the surface acoustic wave, some surface acoustic waves may not reach the output transducer directly, but finally arrive after multiple reflections at the substrate boundary. The third-order transit signal refers to the signal that the surface acoustic wave passes through three propagation paths on the substrate before being received by the output transducer. The generation of this signal may interfere with the normal first-order transit signal, causing signal superposition, making the sensor output signal complicated, and it is difficult to accurately parse the real signal corresponding to the measured physical quantity, thereby affecting the measurement accuracy. For example, in high-precision temperature measurement, the triple transit signal may cause a deviation in the relationship between temperature and sensor output, making the measurement result inaccurate. On the other hand, the appearance of the triple transit signal may also mask the changes in the surface acoustic wave caused by some weak changes in the measured physical quantity, reducing the sensor's ability to detect small changes. Summary of the invention

[0003] In view of the deficiencies of the prior art, the present invention provides a third-order transit interference suppression method for a surface acoustic wave device, which achieves high-precision surface acoustic wave sensor response by suppression. The method combines signal processing technology with optimized interdigital transducer parameters.

[0004] To achieve the above object, the present invention provides a method for suppressing third-order transit interference of a surface acoustic wave device, comprising: Obtaining geometric parameters of optimized interdigital transducer; According to the geometric parameters of the optimized IDT, the duration of the input excitation signal is adjusted to perform time separation processing on the direct signal and the triple transit signal; An output time window is obtained according to the duration of the input excitation signal, and three-times transition signal shielding is performed to obtain a pure main signal as a three-times transition interference suppression result.

[0005] Preferably, the geometric parameter optimization of the interdigital transducer includes selecting the period and the number of finger pairs of the interdigital transducer, where the period of the interdigital transducer is set to 40 microns, and the number of input and output interdigital transducer pairs is 40.

[0006] Furthermore, the duration of the input excitation signal is determined based on experimental tests to achieve the best time separation effect between the direct signal and the triple transit signal.

[0007] Furthermore, the high-speed RF single-pole double-throw switch is triggered by the edge of the pulse signal. The rising edge activates the excitation channel, and the falling edge terminates the excitation and starts the receiving channel.

[0008] Preferably, it also includes building an electronic system including a surface acoustic wave sensor, a high-speed RF single-pole double-throw switch, a low-noise amplifier, an IQ demodulator, a low-pass filter, and a field programmable gate array component.

[0009] Furthermore, the surface acoustic wave sensor in the electronic system is used to generate and receive surface acoustic wave signals. The high-speed RF single-pole double-throw switch controls the duration of the excitation signal and the signal receiving timing. The low-noise amplifier preliminarily amplifies the received signal. The IQ demodulator mixes the signal to generate four-channel differential output signals. The low-pass filter removes high-frequency noise. The field programmable gate array calculates the phase difference between the reference frequency signal and the delayed response of the surface acoustic wave sensor, and outputs the final measurement result.

[0010] Preferably, it also includes accurately shielding the triple transit signal by the high-speed switch of the electronic system using the field programmable gate array component.

[0011] Preferably, it also includes constructing a mathematical model of the surface acoustic wave propagation process based on theoretical modeling and experimental verification; Using the mathematical model of the surface acoustic wave propagation process to analyze the characteristics of the input electrical excitation signal, the surface acoustic wave propagation process, and the output signal.

[0012] Preferably, it also includes removing the interference of the triple transit signal again based on the adaptive filtering algorithm.

[0013] Compared with the closest prior art, the beneficial effects of the present invention are: By suppressing, a high-precision response of the surface acoustic wave sensor is achieved. Combining signal processing technology with optimized interdigital transducer parameters, a theoretical analysis of the generation mechanism of TTE is carried out. The results show that the interference of SAW by TTE will greatly affect the measurability. At the same time, it is shown that by finely optimizing the IDT parameters, the triple transition echo can be minimized, including carefully designing the input excitation signal and selecting the output time window, so as to achieve the time separation between the main signal and the TTE echo, thereby significantly improving the measurement linearity and reliability in SAW sensing applications. Description of the Drawings

[0014] Figure 1 is a flowchart of a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 2 is a schematic diagram before optimizing the geometric parameters of an interdigital transducer for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 3 is a schematic diagram after optimizing the geometric parameters of an interdigital transducer for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 4 is a schematic diagram before adjusting the excitation signal for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 5 is a schematic diagram after adjusting the excitation signal for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 6 is a schematic diagram of a time-domain output gating window for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figure 7 is a schematic circuit diagram of an electronic system for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention Figure 8 is an actual circuit diagram for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention; Figures 9 - 12 is a temperature test result graph using a network sorting gating function for a method for suppressing third-order transit interference for surface acoustic wave devices provided by the present invention. Detailed implementation manners

[0015] The following further elaborates on the detailed implementation manners of the present invention with reference to the accompanying drawings.

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. Embodiment

[0017] The present invention provides a method for suppressing third-order transit interference for surface acoustic wave devices, as Figure 1 shown, including: S1. Obtain the geometric parameters of the optimized interdigital transducer; S2. Adjust the duration of the input excitation signal according to the geometric parameters of the optimized interdigital transducer to perform time separation processing on the direct signal and the triple transit signal; S3. Obtain the output time window according to the duration of the input excitation signal, perform triple transit signal shielding, and obtain a pure main signal as the triple transit interference suppression result.

[0018] The optimization of the geometric parameters of the interdigital transducer includes selecting the period and the number of finger pairs of the interdigital transducer. The period of the interdigital transducer is set to 40 microns, and the number of input and output interdigital transducer pairs is 40.

[0019] The duration of the input excitation signal is determined based on experimental tests to achieve the best time separation effect between the direct signal and the triple transit signal.

[0020] The high-speed RF single-pole double-throw switch is triggered by the edge of the pulse signal. The rising edge activates the excitation channel, and the falling edge terminates the excitation and starts the receiving channel.

[0021] The method for suppressing triple transit interference for a surface acoustic wave device further includes building an electronic system including a surface acoustic wave sensor, a high-speed RF single-pole double-throw switch, a low-noise amplifier, an IQ demodulator, a low-pass filter, and a field programmable gate array component.

[0022] The surface acoustic wave sensor in the electronic system is used to generate and receive surface acoustic wave signals. The high-speed RF single-pole double-throw switch controls the duration of the excitation signal and the signal reception timing. The low-noise amplifier preliminarily amplifies the received signal. The IQ demodulator performs signal mixing processing to generate four-channel differential output signals. The low-pass filter removes high-frequency noise. The field programmable gate array calculates the phase difference between the reference frequency signal and the delay response of the surface acoustic wave sensor and outputs the final measurement result.

[0023] The method for suppressing triple transit interference for a surface acoustic wave device further includes accurately shielding the triple transit signal by the high-speed switch of the electronic system using the field programmable gate array component.

[0024] The method for suppressing triple transit interference for a surface acoustic wave device further includes constructing a mathematical model of the surface acoustic wave propagation process based on theoretical modeling and experimental verification; Analyze the characteristics of the input electrical excitation signal, the surface acoustic wave propagation process, and the output signal using the mathematical model of the surface acoustic wave propagation process; Remove the triple transit signal interference again based on the adaptive filtering algorithm.

[0025] In this embodiment, for a method for suppressing triple transit interference for a surface acoustic wave device, the specific process of the theoretical analysis and model construction is as follows: Analyze signal characteristics: Mathematically model the input electrical excitation signal, the SAW propagation process, and the output signal. The calculation formula for the input electrical excitation signal is as follows: where f is the center frequency and T is the excitation duration.

[0026] The calculation formula for the SAW propagation process from the input to the output IDT is as follows: where hout and hin are the impulse responses of the output and input IDTs respectively, L is the length of the delay line region, and v is the SAW velocity.

[0027] Through analysis, it is concluded that to prevent the direct signal from overlapping with the TTE, the following conditions need to be met: In this embodiment, a method for suppressing the third-order transit interference of a surface acoustic wave device, based on the specific process of the TTE elimination technology optimized by multiple factors, is as follows: 1. IDT parameter optimization: Carefully design the geometric parameters of the IDT, such as selecting appropriate periods, number of fingers, etc. In this technical solution, the IDT period is set to 40 μm, and the number of input / output IDT pairs is 40. By optimizing the IDT parameters, unnecessary acoustic wave reflections are reduced, and the intensity of TTE generation is reduced from the source. Figure 2 Before IDT parameter optimization, Figure 3 After IDT parameter optimization.

[0028] 2. Input excitation signal optimization: Adjust the duration T of the excitation signal. According to theoretical analysis, reasonably shorten the duration of the excitation signal to separate the direct signal and the TTE in time and avoid their overlapping interference with the main signal. For example, in the experiment, by testing different excitation durations, the parameter values that can achieve the best separation effect are found. Figure 4 Before the excitation signal is adjusted, Figure 5 After the excitation signal is adjusted.

[0029] 3. Output time window selection: Use a high-speed RF single-pole double-throw (SPDT) switch to accurately control the output time window. The switch is triggered by the edge of the pulse signal. The rising edge activates the excitation channel, and the falling edge terminates the excitation and starts the receiving channel. During the receiving stage, only select the time window where the direct signal is located for signal acquisition, effectively shielding the TTE and ensuring that the collected signal is mainly the pure main signal without TTE interference.

[0030] Figure 6 For the time-domain output gating window.

[0031] In this embodiment, a method for suppressing the third transit interference of a surface acoustic wave device, the specific process of the SAW delay line type electronic measurement system design and signal processing is as follows: 1. Electronic system architecture: Build an electronic system including components such as a SAW sensor, a high-speed RF SPDT switch, a low-noise amplifier (LNA), an IQ demodulator, a low-pass filter, and a field programmable gate array (FPGA). The SAW sensor is used to generate and receive surface acoustic wave signals. The high-speed RF SPDT switch controls the excitation signal duration and the signal reception timing. The LNA preliminarily amplifies the received signal. The IQ demodulator mixes the signal to generate four differential output signals (I +, I -, Q +, Q -). The low-pass filter removes high-frequency noise to improve the signal quality. The FPGA calculates the phase difference between the reference frequency signal and the delay response of the SAW sensor and outputs the final measurement result. Figure 7 It is the circuit schematic diagram of the electronic system.

[0032] 2. Signal processing flow: First, transmit the grid signal to the input IDT. At the precise moment when the grid cycle ends, the SPDT switch switches to the receiving mode, and the output IDT captures the signal containing the sensing information. After this signal is amplified by the LNA, mixed by the IQ demodulator, and filtered by the low-pass filter, it is subjected to analog-to-digital conversion and then transmitted to the FPGA for phase difference calculation to finally obtain the measurement data. Figure 8 It is the actual circuit diagram. Figure 9 Figure 10 It is the temperature test result graph using the network sorting and gating function. Figure 11 Figure 12 It is the temperature test result graph of the SAW delay line type electronic measurement system.

[0033] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0034] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, and combinations of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device generate means for implementing the functions specified in one or more flows Figure 1 one or more flows and / or blocks Figure 1 or means for implementing the functions specified in one or more blocks.

[0035] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to operate in a specific manner, such that the instructions stored in the computer-readable memory produce a manufactured article including instruction means that implement the functions specified in one or more flows Figure 1 one or more flows and / or blocks Figure 1 or means for implementing the functions specified in one or more blocks.

[0036] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flows Figure 1 one or more flows and / or blocks Figure 1 or means for implementing the functions specified in one or more blocks.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the protection scope of the claims of the present invention.

Claims

1. A method for suppressing third-order transit interference of a surface acoustic wave device, characterized in that: include: Obtaining geometric parameters of optimized interdigital transducer; According to the geometric parameters of the optimized IDT, the duration of the input excitation signal is adjusted to perform time separation processing on the direct signal and the triple transit signal; An output time window is obtained according to the duration of the input excitation signal, and three-times transition signal shielding is performed to obtain a pure main signal as a three-times transition interference suppression result.

2. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 1, characterized in that: The optimization of the geometric parameters of the IDT includes selecting the period and the number of finger pairs of the IDT, wherein the period of the IDT is set to 40 micrometers, and the number of input and output IDT pairs is 40.

3. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 2, characterized in that: The duration of the input excitation signal is determined based on experimental tests to achieve an optimal time separation effect of the direct signal and the triple transit signal.

4. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 3, characterized in that: The high-speed RF single-pole double-throw switch is triggered by the edge of the pulse signal, the rising edge activates the excitation channel, and the falling edge terminates the excitation and starts the receiving channel.

5. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 1, characterized in that: It also involves building an electronic system that includes SAW sensors, high-speed RF SPDT switches, low-noise amplifiers, IQ demodulators, low-pass filters, and field-programmable gate array components.

6. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 5, characterized in that: The surface acoustic wave sensor in the electronic system is used to generate and receive surface acoustic wave signals, the high-speed RF single-pole double-throw switch controls the duration of the excitation signal and the timing of signal reception, the low-noise amplifier performs preliminary amplification on the received signal, the IQ demodulator performs signal mixing processing to generate four-way differential output signals, the low-pass filter removes high-frequency noise, and the field programmable gate array calculates the phase difference between the reference frequency signal and the delayed response of the surface acoustic wave sensor, and outputs the final measurement result.

7. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 1, characterized in that: The invention also includes using a high-speed switch of an electronic system of the field programmable gate array component to accurately shield three-times transition signals.

8. A method for suppressing third-order transit interference of a surface acoustic wave device as claimed in claim 1, characterized in that: It also includes the construction of mathematical models of the surface acoustic wave propagation process based on theoretical modeling and experimental verification; The mathematical model of the surface acoustic wave propagation process is used to analyze the characteristics of the input electrical excitation signal, the surface acoustic wave propagation process and the output signal.

9. The method for suppressing third-order transit interference of a surface acoustic wave device according to claim 1, characterized in that: It also includes removing the interference of the third-time transit signal again based on an adaptive filtering algorithm.

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