Disclosed are a metal-semiconductor-metal two-dimensional electron gas varactor (MSM-2DEG) and a method of manufacturing the same. There is provided an MSM-2DEG varactor having an asymmetric structure, which includes a first gate formed on a semiconductor layer, and a second gate spaced apart at a predetermined distance from the first gate and formed on the semiconductor layer, wherein the first gate and the second gate are different in shape and gate length.

A control apparatus in a static VAR compensator (SVC) system includes a plurality of current supply units for supplying phase currents configuring three-phase current of a power system, a plurality of current sensors for measuring the phase currents, and a controller for determining whether unbalance occurs in the three-phase current based on the phase currents, calculating an error corresponding to the unbalance according to the phase currents if unbalance occurs, and individually controlling at least one of the plurality of current supply units so as to compensate for the error.

A single-chip tunable bandpass filter is provided having a bandpass filter circuit with all tuning components for the bandpass filter circuit formed on the single-chip to provide a programmed center frequency for the tunable bandpass filter. The bandpass filter circuit may include, but is not limited to, a plurality of serially coupled singe stage biquad filter circuits coupled to an input formed on the single-chip and configured to provide a bandpass filtered output signal to an output formed on the single-chip. The bandpass filtered output may be provided by an output buffer formed on the single-chip. The single-chip includes at least one tuning input to receive data for tuning stored in a data register formed on the single-chip. The data register provides control bits to the tuning components that include a programmable resistor responsive to the control bits to vary the programmable resistor to adjust programmed center frequency.

A single-chip tunable bandpass filter is provided having a bandpass filter circuit with all tuning components for the bandpass filter circuit formed on the single-chip to provide a programmed center frequency for the tunable bandpass filter. The bandpass filter circuit may include, but is not limited to, a plurality of serially coupled singe stage biquad filter circuits coupled to an input formed on the single-chip and configured to provide a bandpass filtered output signal to an output formed on the single-chip. The bandpass filtered output may be provided by an output buffer formed on the single-chip. The single-chip includes at least one tuning input to receive data for tuning stored in a data register formed on the single-chip. The data register provides control bits to the tuning components that include a programmable resistor responsive to the control bits to vary the programmable resistor to adjust programmed center frequency.

A voltage controlled oscillator comprises a negative resistance, a first inductor, a fixed capacitor, and a frequency control component. The frequency control component comprises at least one varactor and at least a second inductor connected in series with the at least one varactor. A magnitude of an inductance of the second inductor is selected such that the frequency control component has an effective capacitance range larger than a capacitance range of the at least one varactor.

An electronic device is provided. The electronic device includes a tunable circuit and a driver circuit. The tunable circuit includes a first control terminal and a second control terminal. The driver circuit includes a first driver and a second driver. The first driver is coupled to the first control terminal of the tunable circuit. The second driver is coupled to the second control terminal of the tunable circuit.

This invention provides a mobile terminal and a network searching method for overcoming crystal aging issue. The method includes the step of: searching network by invoking parameters stored in a first area of a volatile RAM; if the searching is failed, searching network by invoking parameters stored in a second area of the volatile RAM; if the searching is failed and the number of network searches is larger than a first predetermined value, reacquiring parameters and searching network; if the searching is succeeded, updating the parameters in the first area with the reacquired parameters. By this method, the invention can effectively solve the problems caused by crystal aging or defective crystals, and increases the robustness of the network searching.

An exponentially-scaling switched impedance circuit includes: two or more impedance scaling circuits, wherein each impedance scaling circuit comprises: an input port; an output port; and a switched impedance circuit connected in parallel to the output port. Each impedance scaling circuit is configured to provide an effective impedance at the input port corresponding to a scaled-down version of the exponentially-scaling switched impedance circuit. The two or more impedance scaling circuits are connected in a cascade such that an input of an impedance scaling circuit is connected to an output of a previous impedance scaling circuit and/or an output of the impedance scaling circuit is connected to an input of a next impedance scaling circuit.

An active filtering system designed to be connected in parallel with an electric power supply network providing a main power supply current including a disturbing current, the system including at least one capacitor, a controlled current generator including an electric power supply intended to generate a positive determined voltage or a negative determined voltage and connected in series with the capacitor, a device for controlling the controlled current generator, designed to generate a compensation current to be applied to the main current in order to compensate the disturbing current while keeping a decoupling current measured at the connection point between the current generator and the capacitor at a value suitable for not saturating the current generator.

Disclosed is an electronic device including a substrate, a radio frequency (RF) modulation element, a control circuit and a radio frequency (RF) choke. The RF modulation element, the control circuit and the RF choke are disposed on the substrate. The RF choke is electrically coupled between the RF modulation element and the control circuit. The orthographic projections of the RF modulation element, the control circuits and the RF choke on the substrate do not overlap each other.