Surface acoustic wave device and electronic apparatus

A surface acoustic wave and electronic equipment technology, applied in the direction of electrical components, impedance networks, etc., can solve the problems of reduced yield and unsuitable for high frequency

Inactive Publication Date: 2006-05-31
SEIKO EPSON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0011] However, the reflective inversion IDT electrode has three electrode fingers per wavelength. Compared with the commonly used single-type IDT electrode, which has two electrode fingers per surface acoustic wave wavelength, in order to adapt to higher frequencies, It is necessary to further reduce the width of the IDT electrode, which is not suitable for high frequency, and it is expected that the yield will drop during the manufacturing process.

Method used

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  • Surface acoustic wave device and electronic apparatus

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no. 1 Embodiment approach

[0046] Next, an embodiment of the present invention will be described by taking a SAW resonator as an example of a surface acoustic wave device.

[0047] image 3 is a schematic diagram of a SAW resonator as a surface acoustic wave device with a single-type IDT electrode. image 3 (a) is a schematic plan view of a SAW resonator, image 3 (b) is a schematic cross-sectional view along the section line A-A of (a) of the figure.

[0048] The SAW resonator 10 is composed of: an IDT electrode 12 having electrode fingers 21 , 22 on the surface of a quartz substrate 11 ; and reflectors 14 , 15 provided at both ends of the IDT electrode 12 . The IDT electrode 12 is arranged such that the respective electrode fingers 21 , 22 engage with each other. The electrode fingers 21 and 22 are formed according to the thickness H and the electrode width d, and the interval (pitch) P between the electrode fingers 21 and the electrode fingers 22 is continuously formed at equal intervals. In addi...

no. 2 Embodiment approach

[0069] Alternatively, the image 3 The cut-out angle of the quartz substrate 11 of the shown SAW resonator and the propagation direction of the surface acoustic wave are set within the range of Euler angles (0°, 0°≤θ≤180°, 9°≤|ψ|≤46°) .

[0070] At this time, if Figure 4 As shown, when the temperature range is -40°C to 90°C, the amount of frequency variation is a maximum of about 127ppm. The secondary temperature coefficient of the ST-cut quartz substrate is generally -3.4×10 -8 (1 / °C 2 ), when the temperature range is -40°C to 90°C, the frequency variation is about 144ppm.

[0071] In this way, by setting the cutting angle of the quartz substrate 11 of the surface acoustic wave device and the propagation direction of the surface acoustic wave within the range of Euler angles (0°, 0°≤θ≤180°, 9°≤|ψ|≤46°) Within, the amount of frequency variation can be reduced compared to the case of using an ST-cut quartz substrate.

no. 3 Embodiment approach

[0073] Also, you can add image 3 The cut-out angle of the quartz substrate 11 of the shown SAW resonator and the propagation direction of the surface acoustic wave are set within the range of Euler angles (0°, 95°≤θ≤155°, 33°≤|ψ|≤46°) .

[0074] At this time, if Figure 4 As shown, in the case where the temperature range is -40°C to 90°C, the amount of frequency variation becomes a maximum of about 59ppm. In addition, in the in-plane rotating ST-cut quartz substrate, according to the document "Temperature Stability of Surface Acoustic Wave Resonators onIn-Plane Rotated 33°Y-Cut Quartz" JJAP, Vol.42(2003)pp.3136-3138, in Europe In the case of pulling angles (0°, 123°, 43.4°), the second temperature coefficient of the lower limit mode of the stop band is -1.4×10 -8 (1 / °C 2 ), when the temperature range is -40°C to 90°C, the frequency variation is about 59ppm.

[0075] In this way, by setting the cutting angle of the quartz substrate 11 of the SAW resonator and the propagat...

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Abstract

Surface acoustic wave devices and electronic equipment. An object of the present invention is to provide a surface acoustic wave device that uses the upper limit mode of the stop band as the oscillation frequency of the surface acoustic wave device, has excellent frequency-temperature characteristics, and is easy to increase in frequency. As a solution, in a surface acoustic wave device (2) having at least an IDT electrode for exciting a Rayleigh-type surface acoustic wave on the surface of a quartz substrate (1), when expressed in terms of Euler angles (φ, θ, ψ) When representing the cutting angle of the quartz substrate (1) and the propagation direction of the surface acoustic wave, it is set to φ=0°, 0°≤θ≤180°, and 0°<|ψ|<90°.

Description

technical field [0001] The present invention relates to a surface acoustic wave device utilizing an upper-limit mode of a stopband of a Rayleigh-type surface acoustic wave. Background technique [0002] Surface acoustic wave devices represented by SAW (surface acoustic wave) resonators and SAW filters are widely used in the communication field because of their excellent characteristics such as high frequency, small size, and mass production. In particular, a surface acoustic wave device using a quartz substrate typified by ST-cut achieves high precision by utilizing the high-temperature stability of quartz. In recent years, due to the popularization and development of portable communication devices and the like, high-frequency, small-sized, and high-precision surface acoustic wave devices that are stable against temperature changes have been further demanded. [0003] In a surface acoustic wave device, when attempting to increase the frequency and stabilize the temperature,...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/25H03H9/145
CPCH03H9/02551H03H9/02543
Inventor 神名重男
Owner SEIKO EPSON CORP
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