摘要:
A surface acoustic wave reflector includes a piezoelectric substrate and a plurality of perturbation members arranged at a first period on the piezoelectric substrate. A plurality of free-surface regions where no perturbation members exist are formed in an arrangement of the perturbation members.
摘要:
A surface acoustic wave device includes a piezoelectric substrate and plural IDTs for sending and receiving SAW mounted on the substrate. At least one of the IDTs includes a positive electrode including plural positive split electrodes (PSEs) and a negative electrode including plural negative split electrodes (NSEs). The PSEs and NSEs are arranged alternately. Each of the PSEs andNSEs has apair of electrode fingers. Two electrode fingers of each of the split electrodes are different in width in a direction in which a SAW is excited. An angle .alpha. determined by a direction transverse to the electrode fingers from one of the two electrode fingers having a smaller reflection factor toward the other one having a larger reflection factor and a direction in which the SAW excited by the IDT including the split electrodes travels to one of the IDTs for receiving the SAW is equal to or larger than 0.degree. and smaller than 90.degree., i.e., 0.ltoreq..alpha.
摘要:
A surface acoustic wave device includes a plurality of surface acoustic wave filter chips having external connection terminals and a package accommodating the plural surface acoustic wave filter chips. The package is provided with a plurality of terminals for connection with the surface acoustic wave filter chips, and one of the external connection terminals of a first one of the surface acoustic wave filter chips is connected with one of the terminals of the package via a second one of the surface acoustic wave filter chips.
摘要:
The present invention relates to a surface acoustic wave filter which is characterized in that it includes a piezoelectric substrate, a plurality of surface acoustic wave propagation paths arranged in parallel on the piezoelectric substrate and a coupler for coupling the surface acoustic wave propagation paths, an input interdigital transducer and a first reflector are disposed on at least one of the surface acoustic wave propagation paths with intervention of the coupler, and an output interdigital transducer and a second reflector are disposed on at least one of the other surface acoustic wave propagation paths with intervention of the coupler. This construction can reduce the length of the surface acoustic wave filter in a surface acoustic wave propagation direction and can improve the shape factor of a frequency characteristic curve.
摘要:
A surface acoustic wave filter including a piezoelectric substrate, an exciting electrode formed on the piezoelectric substrate and exciting a surface acoustic wave, and a receiving electrode receiving the surface acoustic wave. Both the exciting and receiving electrodes are provided with interdigital electrode fingers having a period p. One of the exciting and receiving electrodes is constructed of a plurality of interdigital electrode sub-units having substantially the same electrode surface areas occupied by interdigital electrode fingers. The interdigital electrode sub-units are disposed in a direction perpendicular to a propagation direction of the excited surface acoustic wave and have a positional relation such that the interdigital electrode sub-units are offset from each other by (n±¼)p, wherein n is an integer, in a direction parallel to the propagation direction of the surface acoustic wave.
摘要:
A surface acoustic wave filter includes a piezoelectric substrate, input and output IDTs, and first and second direction changing electrodes, wherein at least one of the input and output IDTs includes a weighted interdigital transducer, the input and output IDTS being arranged in a direction perpendicular to a propagation direction of a surface acoustic wave (SAW) oscillated by the input IDT. The first direction changing electrode changes the propagation direction of the SAW, which has propagated in a left directed from the input IDT, into a direction towards the output IDT. The second direction changing electrode changes the propagation direction of the SAW, which has propagated in a right direction from the input IDT, into a direction towards the output IDTs and the first and second direction changing electrodes is set for obtaining at the output IDT the SAW having desired frequency characteristics.
摘要:
A SAW filter includes a first SAW resonator having a pair of terminals and a predetermined resonance frequency (frp), the first SAW resonator being provided in a parallel arm of the SAW filter. A second SAW resonator has a pair of terminals and a predetermined resonance frequency (frs) approximately equal to a predetermined antiresonance frequency of the first SAW resonator (fap). The second SAW resonator is provided in a series arm of the SAW filter. An inductance element is connected in series to the first SAW resonator.
摘要:
In a surface acoustic wave filter constituted with a ladder of resonators having a resonance frequency or an anti-resonance frequency, an input current flowing into a resonator in a parallel arm at the first stage from the input is so large as to deteriorate its lifetime caused from a heat generation by the resistance of the thin film wiring. As a measure to this problem, bonding wires (30, 31) connected onto points on connection electrodes (130, 131) for connecting an end of each of plural comb teeth electrodes 111 forming the resonators R.sub.s1 & R.sub.p1, or on a lead conductor (130-1) extended longitudinally from the connection electrode, are allotted at both sides of a center line (C1) of the plural comb teeth electrode group. Furthermore, a bonding wire may be connected substantially onto the center line C1 as well. It is preferable for the bonding wires to be located substantially symmetric with respect to the center line C1. It is preferable that the width along the longitudinal direction of the comb teeth electrodes is larger than a width of the comb teeth electrode.
摘要:
A SAW filter includes a first SAW resonator having a pair of terminals and a predetermined resonance frequency (f.sub.rp), the first SAW resonator being provided in a parallel arm of the SAW filter. A second SAW resonator has a pair of terminals and a predetermined resonance frequency (f.sub.rs) approximately equal to a predetermined antiresonance frequency of the first SAW resonator (f.sub.ap). The second SAW resonator is provided in a series arm of the SAW filter. An inductance element is connected in series to the first SAW resonator.
摘要:
A SAW device comprises a substrate, input and output interdigital electrodes provided on the substrate alternately to form a row of electrodes, and a pair of open strip reflectors disposed at both ends of the row, the input interdigital electrodes having a first pair number representing the number of pairs of opposing finger electrodes forming the input electrode, the output interdigital electrodes having a second pair number representing the number of pairs of opposing finger electrodes forming the output electrode, wherein the first pair number and second pair number are set different in the adjacent input and output electrodes with a predetermined ratio therebetween, the first pair number is changed in each input electrodes in the row, and the second pair number is changed in each output electrodes in the row.