Abstract: A combiner for a Doherty amplifier includes, on and in a dielectric substrate, a carrier input terminal, a peak input terminal, an output terminal, a combining point for combining an output signal from the carrier amplifier and an output signal from the peak amplifier, a first ?/4 line connected between the carrier input terminal and the combining point, a second ?/4 line connected between the combining point and the output terminal, and a first directional coupler. The first directional coupler includes a third ?/4 line electromagnetically coupled to one, to be monitored, of the first ?/4 line and the second ?/4 line.

Abstract: A combiner for a Doherty amplifier includes, on and in a dielectric substrate, a carrier input terminal, a peak input terminal, an output terminal, a combining point for combining an output signal from the carrier amplifier and an output signal from the peak amplifier, a first ?/4 line connected between the carrier input terminal and the combining point, a second ?/4 line connected between the combining point and the output terminal, and a first directional coupler. The first directional coupler includes a third ?/4 line electromagnetically coupled to one, to be monitored, of the first ?/4 line and the second ?/4 line.

Abstract: A unidirectional transducer for a SAW filter having a first group (D) including electrode finger (21) and electrode fingers (14) and (16) arranged at center distances of 3&lgr;/8 and 5&lgr;/8 in a direction opposite to the propagation direction of the surface acoustic wave from electrode finger (21); a second group (E) including electrode fingers (22), (15) and (20) arranged at center distances of 10&lgr;/8, 13&lgr;/8 and 15&lgr;/8 in the propagation direction from electrode finger (21); and a third group (F) including electrode fingers (17), (18) and (19) arranged at center distances of 3&lgr;/8, 5&lgr;/8 and 7&lgr;/8 in the propagation direction from electrode finger (21).

Abstract: A unidirectional transducer for a SAW filter comprises a first group (D), a second group (E) and a third group (F). The first group (D) comprises, the electrode finger (21), the electrode finger (14) arranged at a center distances 3&lgr;/8 in a direction opposite to the propagation direction of the surface acoustic wave (i.e. toward right in the Figure) the electrode finger (21), and the electrode finger (16) arranged at a center distance 5&lgr;/8 in a direction opposite to the propagation direction from the electrode finger(21). The second group (E) comprises the electrode finger (22) arranged at a center distance 10&lgr;/8 in the propagation direction from the electrode finger (21), the electrode finger (15) arranged at a center distance 13&lgr;/8 in a the propagation direction from the electrode finger (21), and the electrode finger (20) arranged at a center distance 15&lgr;/8 in a the propagation direction from the electrode finger (21).

Abstract: A surface acoustic wave filter device includes a piezoelectric substrate having mirror-polished surfaces on both sides, so that it is essentially free from warping. One surface of the substrate is provided with two filter stages which are cascade connected with each other thereby to sufficiently attenuate bulk wave spurious noise below a practically negligible extent. The filter device can be manufactured with an improved yield.

Abstract: A surface acoustic wave filter device includes a substrate which includes quartz or the like piezoelectric material having a small temperature coefficient. The substrate has a surface which is formed with interdigital-type unidirectional transducers on input and output sides, each having a positive electrode and a negative electrode. The positive electrodes and the negative electrodes of each of the input side and output side transducers have electrode fingers which are arranged so as to transduce a harmonic wave of a selected order which is higher relative to a fundamental surface acoustic wave.

Abstract: A surface acoustic wave filter device includes a substrate which comprises quartz or the like piezoelectric having a small temperature coefficient and which is formed with unidirectional transducers of asymmetrical construction. A floating electrode is spaced from intermediate position between adjacent positive and negative electrodes which are arranged in interdigital manner, to effectively utilize a mechanical reflection caused by the floating electrode. In consideration of the sign and magnitude of the reflection factor of the floating electrodes, short-circuited electrodes only are used for the floating electrodes. The surface acoustic wave filter device has improved temperature characteristic, insertion loss characteristic and phase characteristic.