Abstract: A surface acoustic wave resonator includes first and second surface acoustic wave resonator connected in series, and a third surface acoustic wave resonator connected in series with the second surface acoustic wave resonator. Each of the first to third surface acoustic wave resonators includes a pair of comb-shaped electrodes in which electrode fingers of one of the comb-shaped electrodes and electrode fingers of the other one of the comb-shaped electrodes are alternately arranged. The second surface acoustic wave resonator has a lower ratio of a width of the electrode fingers to a pitch between the electrode fingers than the first and third surface acoustic wave resonators.

Abstract: A multiplexer includes a first filter, a second filter, a combining wiring line that provides a combination point at which an input or an output of each of the first filter and the second filter is connected to each other, an antenna terminal to connect the multiplexer to an antenna, an antenna wiring line connected at one end to the antenna terminal and connected at the other end to the combining wiring line, a matching terminal to which a matching inductor to provide matching between the antenna and the multiplexer is to be connected, and a matching wiring line to be connected at one end to the matching terminal and connected at the other end to the combining wiring line.

Abstract: A surface acoustic wave resonator includes first and second surface acoustic wave resonator connected in series, and a third surface acoustic wave resonator connected in series with the second surface acoustic wave resonator. Each of the first to third surface acoustic wave resonators includes a pair of comb-shaped electrodes in which electrode fingers of one of the comb-shaped electrodes and electrode fingers of the other one of the comb-shaped electrodes are alternately arranged. The second surface acoustic wave resonator has a lower ratio of a width of the electrode fingers to a pitch between the electrode fingers than the first and third surface acoustic wave resonators.

Abstract: A multiplexer includes a first filter, a second filter, a combining wiring line that provides a combination point at which an input or an output of each of the first filter and the second filter is connected to each other, an antenna terminal to connect the multiplexer to an antenna, an antenna wiring line connected at one end to the antenna terminal and connected at the other end to the combining wiring line, a matching terminal to which a matching inductor to provide matching between the antenna and the multiplexer is to be connected, and a matching wiring line to be connected at one end to the matching terminal and connected at the other end to the combining wiring line.

Abstract: A multiplexer that includes three or more band-pass filters having different pass bands and has a reduced size, includes a duplexer and a third band-pass filter connected to an antenna terminal, the duplexer and the third band-pass filter are connected in parallel, the duplexer includes a first band-pass filter having a first pass band and a second band-pass filter having a second pass band different from the first pass band, and the third band-pass filter has a third pass band different from the first and second pass bands.

Abstract: An in-band group delay equalizer is formed in a simple circuit configuration so as to have a flat group delay characteristic over a wide frequency band without having a peak of group delay near each passband edge. The in-band group delay equalizer includes a plurality of convex group delay circuits. Each convex group delay circuit is formed of one hybrid coupler and two resonators connected to respective divided output ports of the hybrid coupler. The center frequencies of the respective convex group delay circuits are set to be different from each other so that the overall group delay characteristic of the in-band group delay equalizer becomes flat. The bandwidth and the group delay can be easily adjusted. A distortion compensation amplifier with very low distortion can be realized using such an in-band group delay equalizer.

Abstract: An in-band group delay equalizer is formed in a simple circuit configuration so as to have a flat group delay characteristic over a wide frequency band without having a peak of group delay near each passband edge. The in-band group delay equalizer includes a plurality of convex group delay circuits. Each convex group delay circuit is formed of one hybrid coupler and two resonators connected to respective divided output ports of the hybrid coupler. The center frequencies of the respective convex group delay circuits are set to be different from each other so that the overall group delay characteristic of the in-band group delay equalizer becomes flat. The bandwidth and the group delay can be easily adjusted.