Abstract: A linear, low noise, high quality factor (Q) and widely tunable notch filter circuit includes one or more first reactive elements coupled between a first filter node and a first node. The notch filter circuit further includes a multi-branch circuit having multiple parallel branches and coupled between the first node and a second node. Each branch of the multi-branch circuit includes at least a switch coupled to a variable capacitor. A notch frequency of the notch filter circuit is tunable by adjusting a capacitance of the variable capacitor.

Abstract: An antenna device includes an antenna element and an impedance converting circuit connected to the antenna element. The impedance converting circuit is connected to a power-supply end of the antenna element. The impedance converting circuit is interposed between the antenna element and a power-supply circuit. The impedance converting circuit includes a first inductance element connected to the power-supply circuit and a second inductance element coupled to the first inductance element. A first end and a second end of the first inductance element are connected to the power-supply circuit and the antenna, respectively. A first end and a second end of the second inductance element are connected to the antenna element and ground, respectively.

Abstract: Exemplary embodiments of the present disclosure provide a method and controller for damping multimode electromagnetic oscillations in electric power systems which interconnect a plurality of generators and consumers. The controller for damping such oscillations includes a phasor measurement unit (PMU) and a power oscillation damper (POD) controller. Each oscillating mode signal is damped and then superposed to derive a control signal. A feedback controller is used to feedback the control signal to a power flow control device in the power system.

Abstract: An RF coupling circuit including a transformer and a parallel AC-coupling capacitor can advantageously ameliorate substantial attenuation of a signal, prevent destabilization of any feedback loop, and simplify the circuit design process. The AC-coupling capacitor can act as an “averager”, i.e. both the input and output sides of coupling circuit represent capacitances equal to the average of the input and the output capacitances. Thus, the inductors for tuning them out can become equal, thereby allowing a symmetric (or near symmetric) transformer to be used in the RF coupling circuit. When tuned properly, the transformer plus AC-coupling capacitor can also advantageously provide better in-band gain as well as frequency selectivity than other conventional coupling circuits.

Abstract: A noise filter includes a plurality of LC parallel resonant circuits having a plurality of coils which are connected in series and electrically connected to external electrodes at both ends thereof, and capacitors which are connected in parallel to the coils, respectively, and are disposed inside an insulator while being sequentially connected in tandem to signal wires. Resonance frequencies of the respective LC parallel resonant circuits are preferably different from each other. Further, a shield electrode is disposed between the coils, and the shield electrode also defines a capacitance-forming electrode for preventing magnetic coupling between the two coils.

Abstract: A high-performance integrable tunable inductor includes a "primary" coil and a "drive" coil placed in close proximity to each other and simultaneously driven with primary and drive currents, respectively. The drive current induces mutual components of inductance in the primary coil which vary with the phase and amplitude relationship between the two currents. These relationships are controlled to precisely establish the impedance of the primary coil, allowing the inductor to be "tuned" to provide a desired inductance or resistance by simply varying the phase and amplitude relationships appropriately. Inductance values tunable over ranges of about 2:1 and Q values of nearly 2000 have been demonstrated. The primary coil can also be made to operate as a relatively large integrated capacitance by setting the phase and amplitude relationships appropriately.

Abstract: A transmission line resonator is disclosed which has a resonance frequency that is electrically controllable by control voltage. A reactive circuit is coupled in parallel between two coupling points on the transmission line resonator. The reactive value of the reactive circuit is changed by the control voltage. The reactive circuit can be inductive or capacitive. The control voltage can switch the reactive circuit in parallel with a part of the transmission line resonator between the coupling points, or can control the capacitance value of a capacitance diode disposed in parallel with a part of the transmission line resonator between the coupling points.

Abstract: A selected inductance can be provided by a three-layer structural spiral inductor having an inductor conductive part disposed between two ground electrodes within an electric insulating substrate. This is carried out by eliminating a particular portion of one of those ground electrodes formed on the outer surface of the substrate until a desired inductance is obtained, beginning at a portion of such electrode corresponding to an exposed part of a through hole joint which is electrically connected to an inner peripheral end of a spiral inductor conductive part.

Abstract: A computer network interface ("NIC") exhibits reduced electromagnetic interference and emission through capacitively coupling an output transformer center tap both to reference ground and to logic ground of the NIC's transceiver. Transmit signal lines on both sides of the transceiver are also capacitively coupled to both grounds. Other aspects of the invention reduce electromagnetic interference and emission through improvements in the construction of the NIC printed circuit board and the technique for intercoupling a plurality of NIC's using shielded twisted-pair cable.

Abstract: A quadruple tuned 400 MHz IF filter comprises a rectangular substrate having a foil pattern of four inductors formed on one side thereof with four leadless capacitors and three lead type coupling capacitors interconnected between the inductors and the foil to form a filter. The inductors are arranged in a generally U-shaped configuration with the input inductor and output inductor being located at the legs of the U adjacent to each other for providing electromagnetic coupling between the input and output of the filter to sharpen the response of the filter along the skirts of the response curve. A triple tuned filter includes three helical resonators that are coupled by mutual stray capacitances. Output to input coupling is achieved with two wires connected to the input and output helical resonators and positioned adjacent to the middle helical resonator.

Abstract: To improve the effect of a filter circuit for the harmonics, which contains an L-C-R series resonant circuit in at least one loop, a variable supplementary current excitation which compensates the residual harmonic current in the consumer arrangement at least approximately, is coupled into the series resonant circuit, the supplementary current excitation preferably being supplied by a compensation transformer which is controlled by the current in the loop, the compensation transformer being excited by a source and controlled by an auxiliary transformer arranged in the loop.