Abstract: A signal amplifier includes a band suppression filter configured to suppress a preset band among bands included in an input signal, a first common source-type amplifier connected between a supply terminal of a driving voltage and a ground terminal and configured to amplify a first input signal separated from an output signal of the band suppression filter in a common input node to provide a first amplified signal to a common output node, a second common source-type amplifier configured to amplify a second input signal separated from the output signal of the band suppression filter in the common input node to provide a second amplified signal to the common output node, and an output matcher configured to match levels of impedance between the common output node and an output terminal and to transfer a combined signal to the output terminal.

Abstract: A surface acoustic wave (SAW) device formed by an unitary insulating, magostrictive ferrite, slab whose easy axis of magnetization is initially (prior to the application of a d.c. magnetic biasing field) perpendicular to the direction of SAW-wave propagation. For example, the easy axis of magnetization in a single-crystal lithium ferrite slab is the <111> axis. Therfore this axis is aligned perpendicular to the SAW wave propagation direction and parallel to the edges of the SAW device. Application of a dc magnetic field swings the magnetic moments such that they will be parallel with the SAW wave propagation. Materials useful in carrying out this invention are those which have (1) an easy axis of magnetization, (2) good insulator qualities and (3) the magnetostrictive property. A dc magnetic field is applied parallel with the SAW direction or perpendicular to the easy axis of the material in order to align the magnetic moments in the direction of the SAW wave propagation.