Nihon Dempa Kogyo Co., Ltd.

Takehito Ishii

Fumio Asamura

Masaki Hirose

Shunichi Wakamatsu

Takeo Oita

Noritoshi Kimura

Yukio Akazawa

Hiroki Hamaguchi

An oscillator circuit includes a first resonator, a second resonator, and a frequency adjusting unit. The second resonator has a frequency characteristic different from a frequency characteristic of the first resonator. The frequency adjusting unit is configured to change a ratio between a contribution of the first resonator and a contribution of the second resonator so as to adjust an output frequency.

Oscillator circuit

A temperature-controlled crystal oscillating unit and oscillator are provided, which can stabilize an output frequency thereof, have firmness against shock of falling etc., and are suitable for miniaturization and mass production. A crystal blank for the temperature-controlled crystal oscillating unit is formed by an inner region which is an oscillating plate; an outer region which surrounds the periphery of the inner region; and a connection portion which connects the inner region with the outer region. Electrodes are formed on two surfaces of the inner region, and a heater and a temperature sensor are disposed to surround the periphery of the electrode on one surface of the inner region where the electrode is formed thereon. The electrodes, the heater and the temperature sensor are respectively connected with terminals on the outer region by leads. A contact area between the temperature sensor and a crystal is increased.

Temperature-controlled crystal oscillating unit and crystal oscillator

Provided is an oscillator using an MEMS resonator, which can reduce an influence of noise of a TIA and improve phase noise characteristics of an oscillator output. The oscillator includes an MEMS resonator, a TIA, a buffer amplifier, and a current/voltage converter that couples, by electromagnetic induction, with a wiring line via which an output of the MEMS resonator is fed to the TIA, so as to convert a current flowing in the wiring line to a voltage and output the voltage to the buffer amplifier. Thus, the oscillator output is extracted from the current/voltage converter. Further, the current/voltage converter is provided in the form of an oscillation output coil provided so as to surround the wiring line in a noncontact manner, in which oscillation output coil one end is connected to ground and the other end is connected to the buffer amplifier.

Oscillator

A high-frequency voltage-Controlled oscillation circuit which does not oscillate abnormally, is improved in phase noise, and has a small circuit scale. A phase shift circuit composed of third or more order odd &#x3c0; low-Pass filter and capacitive variable-reactance elements (D, D) connected to the input and output of the low-pass filter in series respectively is inserted in a feedback loop of a transistor of an oscillation amplifier circuit. The low-pass filter is composed of an inductive reactance element (L) connected to the feedback loop in series and capacitive variable-reactance elements (D, D) parallel connected to the input and Output of the inductive reactance element (L). The inductive reactance element (L) is a C-Shaped, a donut-Shaped, or a U-Shaped microstrip line. Thus, a high-frequency voltage-Controlled oscillation circuit is realized.

High-frequency voltage-controlled oscillation circuit

In a concentration sensor using a piezoelectric piece, for instance, a quartz piece in which the natural frequency is varied by adsorption of a sensing target, the object of the present invention is to make the concentration sensor applicable to various fluids to be measured different in viscosity while restricting consumption of the oscillation energy due to interelectrode capacitance, and to be able to cope with plural types of concentration sensors while using a common oscillation circuit. As a concrete means for solving the problem, an inductor is connected in parallel to the piezoelectric piece, and its inductance value is determined based on the relation between inductance values and oscillation loop gains in a gap between the inductance value Lmax canceling the interelectrode capacitance in a resonance frequency of the piezoelectric piece and the inductance value Lmin evaluated as the minimum value among the inductance values with which the piezoelectric piece can oscillate in a state of being immersed in a measuring fluid.

Concentration sensor and concentration detector

To provide a Colpitts oscillation circuit formed with a quartz resonator and a transistor amplifier circuit, which can secure sufficient negative resistance, obtain stable oscillation, negate the need for an amplitude control circuit, and realize stabilization against temperature variations. In order to solve the problem, a structure in which the impedance of a tuning circuit provided in a collector of the transistor exhibits inductivity at the oscillation frequency is provided. The impedance ratio at the oscillation frequency of a capacitor Cconnected between a base and an emitter to a capacitor Cconnected between the emitter and a ground, of the transistor is set at 3 to 1 or more. Furthermore, the impedance of capacity Cconnected between the base and the emitter at the oscillation frequency is set at 300 &#x3a9; or more. A bias resistance Rconnected between the collector and the base of the transistor is set at 3 k&#x3a9; or less. A temperature compensation diode Dis inserted in series between the base and the ground (GND) between the transistor.

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Saitama, Japan

Takehito Ishii