Alps Electric Co., Ltd.

Yutaka Chiba

Yasuhiro Ikarashi

Hiroki Kobayashi

Hiroki Noumi

A voltage controlled oscillator comprises an oscillation transistor, a varactor diode, a resonance circuit which is coupled to the oscillation transistor, and a switching diode which changes over a resonance frequency of the resonance circuit, wherein the resonance circuit includes a first strip conductor which is served for grounding a cathode of the varactor diode in terms of direct current and a second strip conductor which is served for coupling a cathode of the varactor diode with the oscillation transistor, the switching diode is connected to the first strip conductor in parallel in terms of high frequency and has a cathode thereof grounded, and a control voltage which is served for changing a capacitive value of the varactor diode is applied to a connection point between the cathode of the varactor diode and the second strip conductor through a choke inductor.

Voltage controlled oscillator with enhanced sensitivity of change of oscillation frequency

In a voltage controlled oscillator for switching oscillation frequency bands by supplying a band switching signal to an LC resonator circuit that is connected in a phase locked loop having a phase comparator and a loop filter and sets oscillation frequencies, the LC resonator circuit includes at least two inductor elements the connection and non-connection of a part of which are switched in response to a band switching signal and a capacitor element in which a voltage variable capacitor element whose capacitance value is adjusted in response to the control voltage from the loop filter is connected in series to impedance elements acting as a composite element that exhibits a capacitance value in oscillation frequency ranges. With this arrangement, when an oscillation signal is selectively output in a high or low frequency band by switching the LC resonator circuit, the voltage controlled oscillator can increase the difference between the rates of change Kv in the high and low frequency bands.

Growing community of inventors

Fukushima-ken, Japan

Yutaka Chiba