Provided is a temperature sensor including a bipolar transistor, a resistor, and a variable resistance circuit. The resistor is provided between a first node coupled to a base node of the bipolar transistor and a collector node of the bipolar transistor. The variable resistance circuit is provided between an emitter node of the bipolar transistor and a ground node.

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.

Provided is a circuit device including: an oscillation circuit oscillating a vibrator, in which the oscillation circuit includes a variable capacitance circuit having a first variable capacitance element and a second variable capacitance element constituted by a first transistor and a second transistor, and a reference voltage supply circuit. The first reference voltage is supplied to a first gate of the first transistor and a capacitance control voltage is supplied to a first impurity region of the first transistor, the second reference voltage is supplied to a second gate of the second transistor and the capacitance control voltage is supplied to a second impurity region of the second transistor, and the capacitance control voltage is supplied to a first common impurity region of the first transistor and the second transistor.

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; an oscillation circuit electrically coupled to the first terminal and the second terminal, and oscillating the vibrator; a third terminal to which an external input signal is input; a switch circuit provided between a first wiring which couples the first terminal and the oscillation circuit with each other and the third terminal, and having a P-type transistor; and a control circuit outputting a regulated voltage, in which a power supply voltage is regulated, as a substrate voltage of the P-type transistor.

An oscillator includes: an external terminal, a resonator, and an oscillation circuit that oscillates the resonator, in which the oscillation circuit includes an amplification circuit and a current source which supplies a current to the amplification circuit, in which the current is set according to a first control signal which is input from the external terminal and a drive level of the resonator is changed according to the setting of the current.

A clock oscillator includes with a pullable BAW oscillator to generate an output signal with a target frequency. The BAW oscillator is based on a BAW resonator and voltage-controlled variable load capacitance, responsive to a capacitance control signal to provide a selectable load capacitance. An oscillator driver (such as a differential negative gm transconductance amplifier), is coupled to the BAW oscillator to provide an oscillation drive signal. The BAW oscillator is responsive to the oscillation drive signal to generate the output signal with a frequency based on the selectable load capacitance. The oscillator driver can include a bandpass filter network with a resonance frequency substantially at the target frequency.

A circuit device includes an oscillation circuit that generates an oscillation signal by using an resonator, a processing circuit that controls the oscillation circuit, and a storage circuit that stores temperature compensation data of an oscillation frequency of the oscillation signal. The processing circuit generates specific PUF information of the circuit device on the basis of the temperature compensation data.

An oscillator includes a resonator and an integrated circuit, the integrated circuit includes an oscillation circuit that oscillates the resonator, a temperature sensor, a temperature compensation circuit that compensates for temperature characteristics of the resonator based on an output signal of the temperature sensor, an output circuit that receives a signal output from the oscillation circuit and outputs an oscillation signal, and a heat generating circuit, and in the heat generating circuit, a current flows in a first period after supply of a power supply voltage from the outside is started to generate heat and no current flows in the second period after the first period ends.

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.

A piezoelectric device package includes a board having a lower surface and an upper surface, a plurality of terminals disposed on the lower surface, a piezoelectric device disposed on the upper surface, a thermistor layer and a resistance layer disposed on the lower surface, and a cap lead covering an upper portion of the board.