Alps Electric Co., Ltd.

Hiroki Kobayashi

Yasuhiro Ikarashi

Yutaka Chiba

Ryutaro Makita

Masaki Tagai

Toru Kozu

Provided is a transistor oscillating circuit capable of reducing change in oscillating frequency due to change in power supply voltage by improving a base bias circuit of an oscillating transistor In a transistor oscillating circuit, an oscillating circuitof which an emitter is connected to ground through an emitter load resistor, a resonance circuitis connected between a base and the ground, and a collector is connected to a power supply terminal, is included, base bias resistorsandare connected between the base and the collector and between the base and the emitter of the oscillating transistor, and a capacitoris connected between the emitter of the oscillating transistorand AC-ground.

Transistor oscillating circuit having low change in oscillating frequency due to change in power supply voltage

When two oscillation signals are output from a common terminal through switching, to reduce attenuation of the oscillation signals, a dual-band oscillator includes a first oscillating transistor for generating an oscillation signal in a first frequency band; a first inductor for supplying power to a collector of the first oscillating transistor; a first switching element for switching the first oscillating transistor; a second oscillating transistor for generating an oscillation signal in a second frequency band; a second inductor for supplying power to a collector of the second oscillating transistor; a second switching element for switching the second oscillating transistor; and an output terminal for outputting the oscillation signal in the first frequency band or in the second frequency band. The first switching element is disposed between the first inductor and the output terminal, and the second switching element is disposed between the second inductor and the output terminal.

Dual-band oscillator

An oscillating circuit includes an oscillating transistor in which the collector or the base is grounded in a high-frequency manner, and a bias resistor connects the emitter of the oscillating transistor to a ground in a direct-current manner. In the oscillating circuit, a resonance unit, having maximum impedance at the oscillation frequency, is interposed between the bias resistor and the ground. Thus, an oscillation signal is obtained from the connection point between the bias resistor and the resonance unit.

Oscillating circuit for suppressing second harmonic wave

A resonance circuit is interposed between a base and a collector of an oscillating transistor and is configured such that a resonance frequency is switched in correspondence with two different frequency bands. A first feedback unit is interposed between the base and an emitter of the oscillating transistor and a second feedback unit is interposed between the emitter and the collector of the oscillating transistor. One of the first feedback unit and the second feedback unit is configured by series-parallel connection of three reactive elements so as to exhibit one of inductive and capacitance characteristics in the two different frequency bands, and the other feedback unit is configured so as to exhibit the same characteristic as that of one feedback unit. As a result, oscillation is performed in the two frequency bands.

Dual band voltage-controlled oscillator

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.

Voltage controlled oscillator

A switch-type oscillating circuit includes a first oscillating circuit for outputting an oscillation signal having a first frequency, which includes a first oscillation transistor and a first switch circuit for turning on and off the first oscillation transistor; a second oscillating circuit for outputting an oscillation signal having a second frequency, which includes a second oscillation transistor and a second switch circuit for turning on and off the second oscillation transistor; and a coupling circuit disposed between the output end of the first oscillating circuit and the output end of the second oscillating circuit, and the input end of a common circuit. A first low-pass filter circuit is connected between the output end of the first oscillating circuit and a common potential point, for attenuating the oscillation signal having the second frequency; and a second low-pass filter circuit is connected between the output end of the second oscillating circuit and the common potential point, for attenuating the oscillation signal having the first frequency.

Switch-type oscillating circuit for providing isolation between first and second oscillating circuits

A buffer amplifier to be connected to an oscillator for outputting an oscillation signal, comprising an amplifier circuit for amplifying the level of the oscillation signal and frequency selective means connected to the output terminal of the amplifier circuit, wherein the fundamental harmonic or the secondary higher harmonic of the oscillation signal is outputted by switching the frequency selective means.

Growing community of inventors

Fukushima-ken, Japan

Hiroki Kobayashi