An oscillator includes: a resonator; an oscillation circuit configured to generate an oscillation signal by the resonator; a clock output terminal; an output circuit configured to output a clock signal to an external processing device via the clock output terminal; a first terminal; and an interface circuit configured to execute communication with the processing device by a data signal. In the communication, the output circuit outputs the clock signal to the processing device that is a master for the communication, and the interface circuit that is a slave for the communication receives, via the first terminal, the data signal that is transmitted from the processing device and synchronized with the clock signal, or transmits, via the first terminal, the data signal to the processing apparatus in synchronization with the clock signal.

A voltage-controlled oscillator comprises a varactor. A capacitance of the first varactor is dependent upon a control voltage. The voltage-controlled also comprises an inductor. The inductor is connected to a center-tap connection. The voltage-controlled oscillator also comprises a power source. The power source is configured to provide a bias voltage to the inductor through the center-tap connection. The voltage-controlled oscillator also comprises a coupling capacitor. The coupling capacitor is located between the inductor and the varactor. The voltage-controlled oscillator also comprises a coupling resistor. The coupling resistor is located between the coupling capacitor and the center-tap connection. The center-tap connection provides the bias voltage to the coupling capacitor through the coupling resistor.

An oscillator includes a first resonator element, a circuit element configured to oscillate the first resonator element to generate an oscillation signal, a first package which includes a substrate, and has a housing space configured to house the first resonator element and the circuit element at one principal surface side of the substrate, a second resonator element which is disposed at another principal surface side of the substrate, and an oscillation frequency of which is controlled based on the oscillation signal, and a leg part which is disposed at the another principal surface side of the substrate, and which is arranged so as to surround the second resonator element in a plan view of the substrate.

A circuit device includes: an output circuit including a waveform-shaping circuit of an oscillation signal and configured to output an output clock signal based on a clock signal subjected to waveform-shaping; a bias voltage output circuit configured to output a bias voltage of the oscillation signal input to the waveform-shaping circuit; a comparator configured to compare a DC voltage obtained by smoothing the clock signal subjected to the waveform-shaping with a reference voltage; a logic circuit configured to set an adjustment value of the bias voltage; and a storage circuit. In a test mode, the logic circuit changes the adjustment value to determine a set value of the adjustment value based on output of the comparator when the adjustment value is changed, and stores the determined set value in the storage circuit.

A circuit includes: an oscillator configured to generate an oscillation clock signal; an NMOS transistor having a source connected with a power terminal of the oscillator, and a drain connected with a first power supply line to which a first power supply voltage is supplied; an operational amplifier configured to control a gate voltage of the NMOS transistor based on a voltage of the power terminal of the oscillator; and a charge pump.

The charge pump is configured to use the oscillation clock signal or a clock signal generated from the oscillation clock signal to boost the first power supply voltage and generate a boosted power supply voltage, and to supply the boosted power supply voltage to the power terminal of the operational amplifier.

A voltage-controlled oscillator comprises a varactor. A capacitance of the first varactor is dependent upon a control voltage. The voltage-controlled also comprises an inductor. The inductor is connected to a center-tap connection. The voltage-controlled oscillator also comprises a power source. The power source is configured to provide a bias voltage to the inductor through the center-tap connection. The voltage-controlled oscillator also comprises a coupling capacitor. The coupling capacitor is located between the inductor and the varactor. The voltage-controlled oscillator also comprises a coupling resistor. The coupling resistor is located between the coupling capacitor and the center-tap connection. The center-tap connection provides the bias voltage to the coupling capacitor through the coupling resistor.

A voltage controlled oscillator includes a first inductor; a first variable capacitance unit including a first variable capacitance element having a variable capacitance and a second variable capacitance element having a variable capacitance; a first node configured for application of a first voltage to the first variable capacitance unit; a cross-coupled unit including a first transistor and a second transistor, an output of the first transistor connected to an input of the second transistor; a current source configured to flow a current through the first inductor, the first transistor, and the second transistor; a second variable capacitance unit including a third variable capacitance element having a variable capacitance, and a fourth variable capacitance element having a variable capacitance; and a second node different from the first node configured for application of a second voltage to the second variable capacitance unit.

An integrated circuit apparatus includes an oscillation circuit that generates an oscillation signal by using a resonator, an output buffer circuit that outputs a clock signal based on the oscillation signal, a DC voltage generation circuit that generates a DC voltage used to generate the oscillation signal or the clock signal, a power source pad to which a power source voltage is supplied, a ground pad to which a ground voltage is supplied, and a clock pad via which the clock signal is outputted. The ground pad and the DC voltage generation circuit are disposed so as to overlap with each other in the plan view.

A circuit device includes an oscillation circuit configured to generate an oscillation signal and a temperature compensation circuit configured to perform temperature compensation for an oscillation frequency of the oscillation signal. The temperature compensation circuit includes a first reference current generation circuit configured to generate a first reference current, a second reference current generation circuit configured to generate a second reference current, a first compensation circuit configured to perform temperature compensation for the oscillation frequency in a first temperature range based on the first reference current, and a second compensation circuit configured to perform temperature compensation for the oscillation frequency in a second temperature range, which is higher than the first temperature range in temperature, based on the second reference current. The first reference current generation circuit reduces the first reference current as a temperature rises, or the second reference current generation circuit reduces the second reference current as the temperature drops.

An oscillating signal generator circuit includes an oscillator circuit, a feedback circuit, and a voltage regulator circuit. The oscillator circuit is configured to generate a first and second oscillating signal at a first and second output terminal according to a first reference voltage. The first and second oscillating signals are a differential pair of signals. The oscillator circuit includes a common mode sensing circuit coupled between the first and second output terminals. The common mode sensing circuit is configured to sense a common mode component of the first and second oscillating signals so as to generate a sense voltage. The feedback circuit, coupled to the common mode sensing circuit, is configured to generate a feedback voltage according to the sense voltage. The voltage regulator circuit is coupled to the oscillator circuit and the feedback circuit, and configured to regulate a supply voltage so as to generate the first reference voltage.