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.

A digitally controlled oscillator (DCO) includes; a current mirror configured to generate a supply current in response to a bias voltage matching a reference current, a variable resistor connected to the current mirror through a first node outputting the reference current and configured to provide a variable resistance in response to a first control signal, an oscillation circuit connected to the current mirror through a second node outputting the supply current and configured to generate an oscillation signal in response to the supply current, and a feedback circuit configured to control the bias voltage in relation to at least one of a voltage at the first node and a voltage at the second node.

A circuit device includes a first terminal to be coupled to one end of a resonator, a second terminal to be coupled to another end of the resonator, an amplifying element configured to amplify a signal from the first terminal to output the signal amplified to the second terminal, a first resistor element disposed on a signal path between an input node and an output node of the amplifying element, a capacitance element disposed on a signal path between the first terminal and the input node, and a first switch element configured to switch electrical coupling between the input node and a ground.

In an example, a system includes an oscillator circuit on a chip. The oscillator circuit includes a charging current generator including a current mirror, an amplifier, and an on-chip resistor, where the on-chip resistor is coupled to a pin on the chip. The oscillator circuit also includes oscillator circuitry coupled to the charging current generator, where the oscillator circuitry includes a comparator, a phase generator, a first capacitor coupled to a first resistor, and a second capacitor coupled to a second resistor. The system also includes an external resistor coupled to the pin, where the external resistor is external to the chip. The system includes an external capacitor coupled to the pin, where the external capacitor is external to the chip.

An oscillating circuit comprises a constant voltage supply circuit, a constant current supply circuit and an oscillating circuit; the constant voltage supply circuit is configured to output constant voltage; the constant current supply circuit is configured to output constant current; and the oscillating circuit is connected to the constant voltage supply circuit and the constant current supply circuit, and is configured to generate an oscillating signal with a preset frequency according to the constant voltage and the constant current.

An oscillator includes: a resonator; an oscillation circuit configured to oscillate the resonator; a first temperature compensation circuit configured to perform a first temperature compensation processing of temperature-compensating for a frequency of a first clock signal generated by oscillation of the resonator by the oscillation circuit; and a second temperature compensation circuit configured to receive the first clock signal subjected to the first temperature compensation processing, and to output a second clock signal subjected to a second temperature compensation processing based on the first clock signal. The first temperature compensation circuit is configured to perform a first-order first temperature compensation processing as the first temperature compensation processing. The second temperature compensation circuit is configured to perform a high-order second temperature compensation processing as the second temperature compensation processing.

A circuit device includes a first terminal to be coupled to one end of a resonator, a second terminal to be coupled to another end of the resonator, an amplifying element configured to amplify a signal from the first terminal to output the signal amplified to the second terminal, a first resistor element disposed on a signal path between an input node and an output node of the amplifying element, a capacitance element disposed on a signal path between the first terminal and the input node, and a first switch element configured to switch electrical coupling between the input node and a ground.

In examples, an electronic device comprises an oscillator circuit configured to provide an output signal and a controller coupled to the oscillator circuit. The controller is configured to receive first and second target rates; dynamically adjust a frequency accuracy of the output signal based on the first target rate; and dynamically adjust an amplitude of the output signal based on the second target rate.

An oscillator circuit includes an oscillating circuit coupled to a vibrator, and a control circuit that controls the oscillating circuit. The oscillator circuit has a normal operation mode in which the oscillating circuit oscillates in a state where a negative resistance value is a first value, and a start mode in which the oscillator circuit shifts from a state where oscillation is stopped to the normal operation mode. In the start mode, the control circuit controls the negative resistance value to increase from a second value which is smaller than the first value.

A resonator is supplied with voltage from a constant-voltage source, and the constant-voltage source outputs output voltage adjusted by a voltage adjustment signal to the resonator. The resonator outputs a clock signal having a frequency varied by varying capacitance in accordance with a received control signal and a frequency adjustment signal, and a frequency of the clock signal is varied by voltage output from the constant-voltage source.