Acoustic surface wave delay line with single-phase single structure

Abstract

Delay line of acoustic surface wave comprises piezoelectric quartz substrate and two pieces of single-phase unidirectional transducer with gold poles. The delay line in single mode control structure includes a long transducer and a short transducer. Comb structure is adopted in the long transducer, and gap between Combs is equal to length of the short transducer. Distance between geometric centers of transducers is equal to length of the long transducer. Single-phase unidirectional structure of pole width control is adopted in the transducer. The delay line possesses features of low insertion loss. Oscillator is operated under state of single mode.

Description

technical field [0001] The present invention relates to a surface acoustic wave delay line (hereinafter referred to as SAW delay line) in acoustic technology, in particular to a surface acoustic wave delay line with a single-phase and unidirectional structure. Background technique [0002] As an example, a surface acoustic wave delay line 1 of a conventional structure is composed of a substrate and two interdigital transducers arranged therein, such as figure 1 As shown, 9 and 10 are interdigital transducers, 8 is a piezoelectric substrate, and the distance between interdigital transducers 9 and 10 is determined according to the delay requirement. [0003] As an example, a conventional SAW delay line 2 with a single-phase and unidirectional structure, such as figure 2 As shown in IEEE 1989 Ultrasonics Symposium Proceeding pp79-89, two control electrode width single-phase unidirectional transducers (abbreviated as EWC / SPUDT) 12 and 13 are placed on the upper surface of a pi...

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Problems solved by technology

[0008] 1. Traditional SAW extension lines with a single-phase and unidirectional structure usually use aluminum as the interdigital electrode, and in some special cases, such as some gas sensor applications, a corrosion-resistant metal is required as the electrode. Electrodes, and aluminum is not suitable for applications in these fields due to its own characteristics such as easy oxidation

[0009] 2. The surface acoustic wave delay line applied to the surface acoustic wave gas sensor in the prior art usually does not have the function of single-mode frequency control and can only be solved by relying on the peripheral circuit, which undoubtedly increases the complexity of the electronic circuit of the sensor system Sex, increasing the system power consumption is not conducive to the stability of the sensor system

[0010] 3. The surface acoustic wave delay line applied to gas sensors in the prior art usually does not adopt a single-phase unidirectional structure, and in practical applications, considering the stability of temperature, the substrate generally used is quartz, so the loss is generally greater than 20dB , the loss is too large, which affects the frequency stability of the SAW oscillator composed of the SAW delay line and the RF amplifier, which in turn affects the sensitivity and stability of the gas sensor composed of the SAW oscillator.

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