A crystal oscillator device is disclosed. The crystal oscillator device includes a casing; a crystal piece; a pair of excitation electrodes; a transmission antenna electrically coupled to one of the excitation electrodes; a reception antenna configured to receive a radio wave from the transmission antenna; and an alarm generator configured to generate an alarm based on a signal whose amplitude is equal to or less than a reference value, the signal being received by the reception antenna.

A crystal oscillator device is disclosed. The crystal oscillator device includes: a crystal oscillator including a casing, a crystal piece, a pair of excitation electrodes configured to excite a main vibration, and a pair of sub vibration electrodes configured to excite a sub-vibration; and an alarm generator configured to generate an alarm based on a signal whose amplitude is equal to or less than a reference value, the signal being generated in the sub vibration electrodes.

A crystal oscillator device is disclosed. The crystal oscillator device includes a crystal piece provided in a casing; a pair of excitation electrodes provided for the crystal piece; a coil provided on the crystal piece; a magnetic flux generating member configured to generate magnetic flux passing through the coil; and an alarm generator configured to generate an alarm based on a signal whose amplitude is equal to or less than a reference value, the signal being generated in the coil.

A crystal oscillator device is disclosed. The crystal oscillator device includes: a casing; a crystal piece provided in the casing; a pair of excitation electrodes provided on the crystal piece; a magnetic flux generating member provided on the crystal piece; a coil through which magnetic flux from the magnetic flux generating member passes; and an alarm generator configured to generate an alarm based on a signal whose amplitude is equal to or less than a reference value, the signal being generated in the coil.

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 includes a crystal resonator; an inverting amplifier configured to be coupled between a pair of excitation electrodes of the crystal resonator; and a control circuit configured to initiate an alarm and raise gain of the inverting amplifier in a case where an index value for representing oscillation amplitude of the crystal resonator in an oscillation state is equal to or lower than a reference value.

An oscillator circuit comprises a crystal oscillator and an inverter. The input of the inverter is connected to the first terminal of the crystal oscillator and the output of the inverter is connected to the second terminal of the crystal oscillator, oscillator circuit is arranged to operate the inverter in its linear operating region. An amplitude regulator has an input connected to the input of the inverter, arranged to provide a first supply current I.sub.AREG to the inverter, where the magnitude of the first supply current is inversely dependent on a magnitude of a voltage at the inverter input. A digital-to-analogue converter is arranged to provide a second supply current I.sub.DAC to the inverter having a magnitude determined by a digital signal applied to a digital input of the digital-to-analogue converter.

An apparatus is disclosed for implementing multi-mode oscillation circuitry with stepping control. In an example aspect, the multi-mode oscillation circuitry comprises a resonator coupled to a first oscillator and a second oscillator. The multi-mode oscillation circuitry is configured to selectively be in a first configuration with the first oscillator in an active state and the second oscillator in an inactive state or a second configuration with the first oscillator in the inactive state and the second oscillator in the active state. The apparatus also includes a step-control circuit coupled to the multi-mode oscillation circuitry. The step-control circuit is configured to cause the first oscillator to switch from the inactive state to the active state and incrementally increase a first gain of the first oscillator based on the first oscillator being in the active state to enable the multi-mode oscillation circuitry to transition from the second configuration to the first configuration.

An oscillator circuit comprises a crystal oscillator and an inverter. The input of the inverter is connected to the first terminal of the crystal oscillator and the output of the inverter is connected to the second terminal of the crystal oscillator, oscillator circuit is arranged to operate the inverter in its linear operating region. An amplitude regulator has an input connected to the input of the inverter, arranged to provide a first supply current I.sub.AREG to the inverter, where the magnitude of the first supply current is inversely dependent on a magnitude of a voltage at the inverter input. A digital-to-analogue converter is arranged to provide a second supply current I.sub.DAC to the inverter having a magnitude determined by a digital signal applied to a digital input of the digital-to-analogue converter.

An apparatus is disclosed for implementing multi-mode oscillation circuitry with stepping control. In an example aspect, the multi-mode oscillation circuitry comprises a resonator coupled to a first oscillator and a second oscillator. The multi-mode oscillation circuitry is configured to selectively be in a first configuration with the first oscillator in an active state and the second oscillator in an inactive state or a second configuration with the first oscillator in the inactive state and the second oscillator in the active state. The apparatus also includes a step-control circuit coupled to the multi-mode oscillation circuitry. The step-control circuit is configured to cause the first oscillator to switch from the inactive state to the active state and incrementally increase a first gain of the first oscillator based on the first oscillator being in the active state to enable the multi-mode oscillation circuitry to transition from the second configuration to the first configuration.