Seiko Epson Corporation

Epson Toyocom Corporation

Katsuro Yoneya

Masahiro Oshio

Michiaki Takagi

Shinji Nishio

Satoru Hayashi

Masahiro Onuki

A surface acoustic wave device comprises a surface acoustic wave element, including: a piezoelectric substrate, a first interdigital transducer unit having a first interdigital transducer and a second interdigital transducer formed on the piezoelectric substrate, and a second interdigital transducer unit having a third interdigital transducer and a fourth interdigital transducer formed on the piezoelectric substrate; a first terminal electrically coupled to the first interdigital transducer; a second terminal electrically coupled to the second interdigital transducer; a first variable resistor electrically coupling the first terminal to the third interdigital transducer; a second variable resistor electrically coupling the first terminal to the fourth interdigital transducer; a third variable resistor electrically coupling the second terminal to the third interdigital transducer; and a fourth variable resistor electrically coupling the second terminal to the fourth interdigital transducer.

Surface acoustic wave device, transmitter, and transceiver

A longitudinally coupled multi-mode SAW resonator filter includes input and output interdigital transducers (IDTs) with a control IDT therebetween to control a state of the surface acoustic wave. The input, output, and control IDTs alternatively arrange two different zones C and E having respective electrode period lengths PC and PE, being equal to a sum of the electrode finger width L and spacing S between electrode fingers, and a number of respective pairs MC and ME of electrode fingers is set to 1 in both zones C and E. Electrode fingers in zones C and E are all connected to a feeder conductor. Hence, a filter having small insertion loss, and a wide fractional bandwidth of 2000-4000 ppm is achieved by canceling and decreasing sums of reflected waves from the electrode fingers in zones C and E, and decreasing the effective reflection coefficient per the electrode finger.

Resonator SAW filter having a control interdigital transducer between input and output interdigital transducers

A surface acoustic wave (SAW) resonator, including: a first interdigital transducer composed of a pair of interdigital electrodes provided in a propagation direction of a surface acoustic wave; a second interdigital transducer composed of a pair of interdigital electrodes provided in parallel to the first interdigital transducer; and a switch that alternately switches the pair of interdigital electrodes of the first interdigital transducer and the pair of interdigital electrodes of the second interdigital transducer; wherein7&#x3bb;&#x2266;B&#x2266;33&#x3bb;

Saw resonator

A surface acoustic wave element includes a pair of interdigital transducers arranged in parallel with a propagation direction of a surface acoustic wave; a reflector prepared at both sides of the interdigital transducers; and a coupling portion, which mutually couples one end of a plurality of electrode fingers constituting one electrode portion of each interdigital transducer to be in common, wherein each of the electrode fingers includes a plurality of straight line portions that intersect with the coupling portion, and a bending portion prepared between these straight line portions.

Surface acoustic wave element

A SAW filter including a piezoelectric substrate, an input electrodeand an output electrodeeach representing an interdigital electrode disposed on the piezoelectric substrateand two reflectorsanddisposed on the piezoelectric substratein an arrangement sandwiching both the input electrodeand the output electrodebetween the reflectors. Each of the electrodesandinclude a plurality of electrode fingersandrespectively. The electrode fingers are partially bent at an angle and include at least two linear sections which are spaced at a distance of &#x3bb;/2 from one another in the propagating direction of the SAWs. The electrode fingersandof the output electrodeand electrode fingersof the reflectorare structured similarly to the electrode fingersandof the input electrode

Surface acoustic wave filter and surface acoustic wave resonator having bent electrode fingers

The invention provides a longitudinal double-mode SAW filter that has a large reflection coefficient by the electrode conductors and having flat pass band characteristics. In the longitudinal double-mode SAW filter, nearly all of higher-order natural mode oscillation displacements ASand Aare made present in the first and second interdigital transducer regions. An electrode finger phase weighting is formed to correspond to a BPSK sign where a phase sign changes into 0 or &#x3c0; at a polarity-changing point on an electrode charge distribution function Q(x) that generates on the electrode due to natural modes of oscillation. A single pair of natural modes, which exist stationary in the direction X of propagation of the surface acoustic waves that are utilized, is selected. A symmetrical mode charge distribution (Q(x), &#x2212;Q(x)) and an obliquely symmetrical mode charge distribution (Q(x), Q(x)) are generated in order to correspond to the regions of IDTand IDTThe PTNG in the control IDTregion is set to be in the range of 1.02 to 1.04 so as to couple the two together.

Growing community of inventors

Azumino, Japan

Katsuro Yoneya