Provided is a circuit device including: a first terminal electrically coupled to one end of a vibrator; a second terminal electrically coupled to the other end of the vibrator; a first coupling wiring electrically coupled to the first terminal; a second coupling wiring electrically coupled to the second terminal; an oscillation circuit having a drive circuit for driving the vibrator via the first coupling wiring and the second coupling wiring, and oscillating the vibrator; and a first capacitor having a metal-insulator-metal (MIM) structure of which one electrode is electrically coupled to the first coupling wiring. The first coupling wiring and the first capacitor having the MIM structure overlap each other in plan view in a direction orthogonal to a substrate on which a circuit element is formed.

A semiconductor device and a method for controlling amplitude of signal in the semiconductor device are provided. The semiconductor device comprises a signal generator configured to output a sinewave, a comparator configured to compare a magnitude of the sinewave with a magnitude of a reference signal at a first timing corresponding to a timing control signal and to output a comparison result, and a control signal adjustor configured to adjust one of the current control signal and a timing control signal depending on the comparison result of the comparator.

A crystal oscillator circuit that can be controlled for fast start-up and for efficient operation is disclosed. The control includes adjusting a voltage applied to a body terminal of a transistor in order to control the amplification of the crystal oscillator. The amplification can be increased, relative to a motional resistance of the crystal oscillator, at start-up to reduce a start-up time necessary for oscillation. The amplification can also be decreased in order to maintain oscillation after start-up more efficiently. In some implementations, the transistor for control is a fully depleted silicon on insulator (FDSOI) transistor that accommodates a wide range of body bias voltages.

An oscillation circuit includes a first node, a first switching element, and a second switching element and has a first mode in which the first switching element does not electrically couple the first external connection terminal and the first node and the second switching element does not electrically couple the first node and the second external connection terminal which is electrically coupled to one end of a resonator and a second mode in which the first switching element electrically couples the first external connection terminal and the first node and the second switching element electrically couples the first node and the second external connection terminal, and in the first mode, a voltage of the first node is fixed.

The circuit device includes a current generation circuit configured to generate a temperature compensation current based on a temperature detection voltage, and a current-voltage conversion circuit configured to perform current-voltage conversion on the temperature compensation current to output a temperature compensation voltage. The current-voltage conversion circuit includes an operational amplifier, and a feedback circuit. The operational amplifier includes a differential section having a current mirror circuit and differential pair transistors, an output section configured to output the temperature compensation voltage, and an RC low-pass filter configured to output a signal obtained by performing a low-pass filter process on an output signal of the differential section to an input node of the output section.

The circuit device includes a current generation circuit and a current-voltage conversion circuit. The current generation circuit generates a temperature compensation current based on a temperature detection voltage from the temperature sensor and temperature compensation data. The current-voltage conversion circuit converts the temperature compensation current into the temperature compensation voltage. The current generation circuit performs a fine adjustment of the temperature compensation current based on lower bits of the temperature compensation data, and performs a coarse adjustment of the temperature compensation current based on higher bits of the temperature compensation data.

A crystal oscillator circuit that can be controlled for fast start-up and for efficient operation is disclosed. The control includes adjusting a voltage applied to a body terminal of a transistor in order to control the amplification of the crystal oscillator. The amplification can be increased, relative to a motional resistance of the crystal oscillator, at start-up to reduce a start-up time necessary for oscillation. The amplification can also be decreased in order to maintain oscillation after start-up more efficiently. In some implementations, the transistor for control is a fully depleted silicon on insulator (FDSOI) transistor that accommodates a wide range of body bias voltages.

An oscillator includes a resonator, a circuit device that is electrically coupled to the resonator and generates a clock signal, a control terminal that is electrically coupled to the circuit device, and an output terminal that is electrically coupled to the circuit device and outputs the clock signal. The circuit device includes an abnormality detection circuit and sets a potential of the control terminal to an abnormality detection voltage when an abnormal state is detected by the abnormality detection circuit.

An oscillator includes a resonator, a circuit device that is electrically coupled to the resonator and generates a clock signal, and an output terminal that is electrically coupled to the circuit device and outputs the clock signal. The circuit device includes an abnormality detection circuit, and when an abnormal state is detected by the abnormality detection circuit, the circuit device changes a signal characteristic of the clock signal.

An oscillator includes a quartz crystal resonator and a circuit device, and the circuit device includes an oscillation circuit and a PLL circuit. The PLL circuit includes a phase comparison circuit that performs a phase comparison between the reference clock signal and a feedback clock signal, a control voltage generation circuit that generates a control voltage based on a result of the phase comparison, and a voltage control oscillation circuit that generates a clock signal having a frequency corresponding to the control voltage, and a frequency division circuit that divides a frequency of the clock signal and outputs the feedback clock signal. An oscillation frequency of the quartz crystal resonator is higher than or equal to 200 MHz, and a phase comparison frequency of the phase comparison circuit is higher than or equal to 200 MHz.