A crystal oscillator device is disclosed. The crystal oscillator device includes: a crystal piece provided in a casing; a pair of excitation electrodes provided on the crystal piece; a light emitting element configured to emit light that is to be reflected by one of the excitation electrodes to generate reflected light; a light receiving element configured to receive the reflected light; and an alarm generator configured to generate an alarm based on a signal upon an index value being less than or equal to a reference value, the signal being generated in the light receiving element, the index value representing an oscillation level of the crystal piece in an oscillating state.

A crystal oscillator device is disclosed. The crystal oscillator device includes: a crystal piece provided in a casing; a pair of excitation electrodes provided on the crystal piece; a light emitting element configured to emit light that is to be reflected by one of the excitation electrodes to generate reflected light; a light receiving element configured to receive the reflected light; and an alarm generator configured to generate an alarm based on a signal upon an index value being less than or equal to a reference value, the signal being generated in the light receiving element, the index value representing an oscillation level of the crystal piece in an oscillating state.

A low-power voltage controlled oscillator is provided. The voltage controlled oscillator includes (2n+1) first circuit components (n is an integer of one or more). An output terminal of the first circuit component in a k-th stage (k is an integer of one or more and 2n or less) is connected to an input terminal of the first circuit component in a (k+1)-th stage. An output terminal of the first circuit component in a (2n+1)-th stage is connected to an input terminal of the first circuit component in a first stage. One of the first circuit components includes a second circuit component and a third circuit component whose input terminal is connected to an output terminal of the second circuit component. The third circuit component includes a first transistor and a second transistor whose source-drain resistance is controlled in accordance with a signal input to a gate through the first transistor.

A low-power voltage controlled oscillator is provided. The voltage controlled oscillator includes (2n+1) first circuit components (n is an integer of one or more). An output terminal of the first circuit component in a k-th stage (k is an integer of one or more and 2n or less) is connected to an input terminal of the first circuit component in a (k+1)-th stage. An output terminal of the first circuit component in a (2n+1)-th stage is connected to an input terminal of the first circuit component in a first stage. One of the first circuit components includes a second circuit component and a third circuit component whose input terminal is connected to an output terminal of the second circuit component. The third circuit component includes a first transistor and a second transistor whose source-drain resistance is controlled in accordance with a signal input to a gate through the first transistor.

An oscillator includes an external terminal, a resonator, and an oscillation circuit that oscillates the resonator. The oscillation circuit includes an amplification circuit and a current source that supplies a current to the amplification circuit, and the current is variably set according to a control signal input from the external terminal.

An oscillator includes an external terminal, a resonator, and an oscillation circuit that oscillates the resonator. The oscillation circuit includes an amplification circuit and a current source that supplies a current to the amplification circuit, and the current is variably set according to a control signal input from the external terminal.

A temperature-controlled RF resonator. The resonator includes an insulating thermal enclosure within which are implemented: at least one resonant element configured to deliver an RF output signal when supplied with an RF input signal; at least one heating element configured to supply thermal energy within the thermal enclosure when the at least one heating element is powered by an LF electric power signal; and at least one temperature sensor configured to deliver an LF electric measurement signal as a function of the temperature inside the thermal enclosure. Such an RF resonator has at least one input/output port crossing the insulating thermal enclosure and propagating at least: one signal from among the RF signals; and another signal from among the LF electric signals.

A temperature-controlled RF resonator. The resonator includes an insulating thermal enclosure within which are implemented: at least one resonant element configured to deliver an RF output signal when supplied with an RF input signal; at least one heating element configured to supply thermal energy within the thermal enclosure when the at least one heating element is powered by an LF electric power signal; and at least one temperature sensor configured to deliver an LF electric measurement signal as a function of the temperature inside the thermal enclosure. Such an RF resonator has at least one input/output port crossing the insulating thermal enclosure and propagating at least: one signal from among the RF signals; and another signal from among the LF electric signals.

A temperature-compensated oscillator includes a resonator element, an oscillating circuit, and a temperature compensation circuit, and a frequency deviation with respect to a frequency at a time point when power supply starts is within a range of ±8 ppb at a time point when 10 seconds elapse from when the power supply starts, within a range of ±10 ppb at a time point when 20 seconds elapse from when the power supply starts, and within a range of ±10 ppb at a time point when 30 seconds elapse from when the power supply starts.

A temperature-compensated oscillator includes a resonator element, an oscillating circuit, and a temperature compensation circuit, and a frequency deviation with respect to a frequency at a time point when power supply starts is within a range of ±8 ppb at a time point when 10 seconds elapse from when the power supply starts, within a range of ±10 ppb at a time point when 20 seconds elapse from when the power supply starts, and within a range of ±10 ppb at a time point when 30 seconds elapse from when the power supply starts.