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.

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.