Acoustic wave device and system
A technology of acoustic waves and surface acoustic waves, applied in the direction of electrical components, impedance networks, etc.
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no. 1 approach
[0027] Figure 2A is a plan view of the surface acoustic wave device according to the first embodiment. For the sake of brevity, the number of electrode indices of the reflector 4 and the IDT is shown less than the actual number. The distance between the electrode fingers of the reflector 4 may be equal to the distance between the electrode fingers of each IDT.
[0028] Figure 2A The shown surface acoustic wave device has a piezoelectric substrate 2 on which five interdigital transducers 10, 12, 14, 16 are arranged along the surface acoustic wave propagation direction (to the right and to the left) and 18 and two reflectors 4 . Among the five IDTs, the three IDTs at odd-numbered positions (2n+1-th positions) from the right end or left end of the group of five IDTs arranged in a row The transducers 10, 14 and 18 are all connected to the unbalanced terminal 6, and the three IDTs 10, 14 and 18 are connected in parallel with each other. The two IDTs 12 and 16 located at even...
no. 2 approach
[0041] A second embodiment is configured with separate comb electrodes of an interdigital transducer.
[0042] Figure 4A is a plan view of the surface acoustic wave device according to the second embodiment. refer to Figure 4A , the interdigital transducers 38 , 40 , 42 , 44 , and 46 are arranged together with the reflector 4 along the surface acoustic wave propagation direction. One of a pair of comb electrodes forming the IDT 40 is divided into comb electrodes 40 a and 40 b that are out of phase with each other by 180 degrees. Likewise, one of a pair of comb electrodes forming the interdigital transducer 44 is divided into comb electrodes 44a and 44b whose phases are different from each other by 180 degrees.
[0043] The IDTs 38, 42 and 46 are connected to the unbalanced terminal 6 and are connected in parallel with each other. That is, one of a pair of comb-shaped electrodes of each of the IDTs 38 , 42 , and 46 is grounded, while the other comb-shaped electrode thereo...
no. 3 approach
[0052] Next, a third embodiment will be described. In the first embodiment, the second IDT from both ends is connected to the balanced terminal (see Figure 2A to Figure 3B ). In contrast, the third embodiment has an exemplary structure in which odd-numbered IDTs from both ends are connected to balanced terminals, and each IDT connected to unbalanced terminals Each device has an even number of electrode fingers.
[0053] in the previously described Figure 1A In , an IDT 14 having an even number of electrode fingers is connected to the unbalanced terminal 6 . Each of the IDTs 12, 14, and 16 is provided with an even number of electrode fingers, and the IDTs 12 and 16 are out of phase with each other by 180 degrees. In the third embodiment connect multiple such as Figure 1A A surface acoustic wave device configured as shown.
[0054] Figure 6A is a plan view of the surface acoustic wave device according to the third embodiment. Such as Figure 6A As shown in , among the...
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