Abstract: A MEMS resonator, a method for manufacturing thereof, and a filter are provided in which a first-order oscillation mode can be used and an S/N ratio of an output signal can be improved. Further, a communication apparatus of high reliability using the filter is provided. A MEMS resonator of the present invention includes an output electrode, a beam capable of oscillating disposed on an input side to face the output electrode and an input electrode, in which the output electrode and the input electrode 27 are separated from the beam in terms of DC. A filter of the present invention includes the above-described MEMS resonator. A communication apparatus of the present invention includes a filter to limit a band of a transmission signal and/or reception signal, and the above-described filter according to the present invention is used as the filter.

Abstract: Provided are an on-chip balun, a transceiver using the on-chip balun, and a method for fabricating the on-chip balun. The on-chip balun includes: a first metal winding including a port grounded and a port to which an unbalanced signal is input; a second winding outputting an induced current generated by the first metal winding as two signals having about equal intensity and a phase difference of about 180°; and a ground shield positioned between the first and second metal windings and having a symmetric structure so as to generate a symmetric parasitic capacitance between the ground shield and the second metal winding. The ground shield can be inserted between the first and second metal windings to remove an asymmetrical parasitic capacitance so as to reduce a phase imbalance and a gain imbalance of an output value of the second metal winding. As a result, a highly balanced on-chip balun can be fabricated.

Abstract: A filter device substrate 1 of the present invention is formed by stacking a plurality of ceramic layers 12, 14, and includes a filter chip mounting portion for mounting a transmission filter chip 2 and a reception filter chip 3. Arranged on a surface of one ceramic layer 12 are a signal input pad 73, a signal output pad 7, a signal input side ground pattern 44 and a signal output side ground pattern 43 for connecting a signal input terminal C, a signal output terminal D, a signal input side ground terminal G and a signal output side ground terminal G, respectively, of the reception filter chip 3. The signal input side ground pattern 44 and the signal output side ground pattern 43 are connected to each other by a connection wiring pattern 45 on the surface of the one ceramic layer 12.

Abstract: A method of manufacturing a surface acoustic wave device formed in one chip and including over a semiconductor substrate at least an IC region and a surface acoustic wave element region that are horizontally disposed, the method including: forming in the IC region over the semiconductor substrate a semiconductor element layer that includes a semiconductor element and an insulation layer covering the semiconductor element and being deposited also in the surface acoustic wave element region; forming over the semiconductor element layer a wire layer that includes a plurality of wires coupled to the semiconductor element and a wire insulating film deposited over the plurality of wires to provide insulation among the wires, the wire insulating film being deposited also over the insulation layer in the surface acoustic wave element region; forming an interlayer insulating film having a flattened surface on the wire insulating film in the IC region and the surface acoustic wave element region; forming a piezoelectri

Abstract: A micro-resonator of a single structure which outputs signals of two resonance frequencies of mutually opposite phases and in which different resonance frequencies are adjusted independently is provided. The micro-resonator includes: an oscillation portion 6 sustained with a gap by support portions 8 [8A, 8B] and an input electrode 3 and an output electrode 4 that become lower electrodes facing the oscillation portion 6 across the gap, in which the input electrode 3 and the output electrode 4 are disposed to face each other along a line intersecting the oscillation portion 6, the oscillation portion 6 generates torsional oscillation and flexural oscillation, and output signals of two resonance frequencies close to each other based on different resonance modes have mutually different phases by 180°.

Abstract: A multiple resonance filter includes at least three multilayer capacitors having at least two different capacitances. The at least three multilayer capacitors are adjacent each other. Two of the at least three multilayer capacitors have a same capacitance. The two capacitors with the same capacitance are on outer ends of an arrangement formed by the at least three multilayer capacitors.

Abstract: A radiation noise suppression circuit for a differential transmission line includes a differential transmission line which has plus line signal wiring to which a plus line signal of a differential signal is applied, and minus line signal wiring to which a minus line signal of the differential signal is applied, and connects a differential driver and a differential receiver. Plus line signal GND wiring and minus line signal GND wiring which are connected between the differential driver and the differential receiver are wired along the differential transmission line. A distance between the plus line signal wiring and the plus line signal GND wiring is substantially equal to a distance between the minus line signal wiring and the minus line signal GND wiring.

Abstract: A radiation noise suppression circuit for a differential transmission line includes a differential transmission line which has plus line signal wiring of a differential signal and minus line signal wiring of the differential signal, and connects a differential driver and a differential receiver; signal GND wiring. A first impedance element and a second impedance element have substantially the same impedance value, and are connected in series between the plus line signal wiring and the minus line signal wiring at a location nearer to the differential receiver than a coil unit. A third impedance element is connected to a junction point. The first impedance element and the second impedance element are connected.

Abstract: A switchable dual-band filter comprises first and second switchable resonators, a coupling structure having two ends respectively connecting the first and the second switchable resonators, an input impedance conversion circuit connecting an input terminal and the first resonator, and an output impedance conversion circuit connecting an output terminal and the second resonator. The coupling structure couples the first resonator to the second resonator, and vice versa. The input/output impedance conversion circuit converts the impedance on the input/output terminal into two distinct impedances that correspond to a first and a second operating frequency. The filter is simple in structure, occupies a smaller circuit area, and is cost-effective in manufacturing. The impedance at both operating passbands can also be matched properly.

Abstract: A noise filter includes a capacitor having a hot side input terminal, a hot side output terminal, a ground side input terminal, and a ground side output terminal. A circuit board includes a hot side input electrode connected to the hot side input terminal, a hot side output electrode connected to the hot side output terminal, a ground side input electrode connected to the ground side input terminal, and a ground side output electrode connected to the ground side output terminal. The impedance of the ground side input terminal seen from the ground side output electrode is larger than both the impedance of the ground side output terminal seen from the ground side output electrode and the impedance of the hot side output terminal seen from the ground side output electrode. For this purpose, a stray capacitance formed between the ground side input electrode and the ground side output electrode is reduced by increasing a gap therebetween. Accordingly, excellent noise-reducing characteristics are provided.

Abstract: To provide a common mode radiation inhibit circuit for a differential transmission line which can inhibit quadratic common mode radiation by ensuring a continuity of grand level at a point of change of a signal grand, including a differential transmission line which is constituted of a pair of signal wiring, and transmits differential signals, signal grounds which are arranged along the differential transmission line, and each have a change point on its way, a transformer, and a reference ground, wherein a primary side of the transformer is connected between an electric midpoint of the pair of signal wiring, and the signal ground at one side of the front and back of the change point of the signal grounds, wherein the secondary side of the transformer is connected between the electric midpoint of the pair of signal wiring and the signal ground at another side of the front and back of the change point, and wherein the reference ground is connected to a point which becomes a neutral sheet of the primary side of