A circuit device includes an oscillation circuit that generates an oscillation signal by using a vibrator, a frequency adjustment circuit that adjusts an oscillation frequency of the oscillation circuit based on frequency adjustment data, a temperature sensor circuit that outputs temperature data, an arithmetic operation circuit, and a storage circuit. The arithmetic operation circuit outputs converted temperature data by performing, on the temperature data, conversion processing in which a slope of the converted temperature data with respect to the temperature data in a first temperature range is different from a slope of the converted temperature data with respect to the temperature data in a second temperature range. The storage circuit stores a lookup table representing a correspondence between the converted temperature data and the frequency adjustment data.

Disclosed are a crystal oscillator, a chip, and an electronic device. The crystal oscillator includes: an oscillating circuit, including: a crystal, an amplification circuit, a first load capacitor, and a second load capacitor, where the first load capacitor and the second load capacitor are respectively connected to a first terminal and a second terminal of the crystal; and a first Miller multiplication circuit, where an input terminal and an output terminal of the first Miller multiplication circuit are respectively connected to two terminals of the first load capacitor, and the first Miller multiplication circuit is configured to increase a first load capacitance of the oscillating circuit, where the first load capacitance is a capacitance between the first terminal of the crystal and the ground. According to this technical solution, an area occupied by the load capacitor as well as circuit costs can be reduced.

A reconfigurable crystal oscillator and a method for reconfiguring a crystal oscillator are provided. The reconfigurable crystal oscillator includes a transconductance circuit, a feedback resistor, a crystal tank, an input-end capacitor and an output-end capacitor. Both of the feedback resistor and the crystal tank are coupled between an input terminal and an output terminal of the transconductance circuit. The input-end capacitor is coupled to the input terminal of the transconductance circuit, and the output-end capacitor is coupled to the output terminal of the transconductance circuit. In particular, the transconductance circuit is configured to provide a transconductance, and when an operation mode of the reconfigurable crystal oscillator is switched, an input-end capacitance of the input-end capacitor and an output-end capacitance of the output-end capacitor are switched, respectively.

A frequency variable oscillator generates a clock having a frequency according to a control signal. A reference current source generates a reference current. A path selector distributes the reference current to a first path and a second path in a time-sharing manner in synchronization with the clock. An F/V conversion circuit includes a capacitor connected to the first path, and charges or discharges the capacitor with the reference current and generates a detection voltage. The reference voltage source includes a resistor connected to the second path, and outputs a reference voltage according to a voltage across the resistor. A feedback circuit adjusts a control signal so that the detection voltage approaches the reference voltage.

A circuit device includes an oscillation circuit and a processing circuit. The oscillation circuit includes a variable capacitance circuit configured by a capacitor array and oscillates at an oscillation frequency corresponding to the capacitance value of the variable capacitance circuit. First temperature data and second temperature data subsequent to the first temperature data are input to the processing circuit as temperature data. In the period between the start of the capacitance control based on the first temperature data and the start of the capacitance control based on the second temperature data, the processing circuit switches the first capacitance control data corresponding to the first temperature data and the second capacitance control data different from the first capacitance control data in a time-division manner to be output to the variable capacitance circuit.

A switched capacitor arrangement for tuning a differential circuit is disclosed. The switched capacitor arrangement comprises a first node, a second node and a third node. The switched capacitor arrangement further comprises a first capacitor (C1) coupled between the first node and the second node, a second capacitor (C2) coupled between the second node and the third node, and a first switch branch comprising a first switch (S 1) coupled between the second node and a signal ground node. The first switch (S 1) has an on state and an off state. The first node and third node are configured to be connected to respective differential nodes (Vtank, −Vtank) of the differential circuit. The switched capacitor arrangement is configured to tune the differential circuit by controlling the state of the first switch.

An oscillator includes a resonator, sustaining circuit and detector circuit. The sustaining circuit receives a sense signal indicative of mechanically resonant motion of the resonator generates an amplified output signal in response. The detector circuit asserts, at a predetermined phase of the amplified output signal, one or more control signals that enable an offset-reducing operation with respect to the sustaining amplifier circuit.

Differential electro-mechanical oscillating circuits are described. These circuits may be used in a variety of contexts to produce differential oscillating signals, such as sine waves or square waves. A switched capacitor circuit (SCC) is used to prevent low-frequency locking, whereby the output of the resonator would otherwise lock to a constant value. More specifically, the SCC provides an impedance in parallel to the resonator between the output terminals of oscillating circuit. The SCC is designed so that, at low frequencies, its impedance is lower than the impedance of the resonator. The presence of such an impedance prevents the formation of an open circuit between the output terminals, thus maintaining the oscillating circuit in the oscillation mode. The differential electro-mechanical oscillating circuits described herein may be used to produce clock signals or otherwise to produce periodic reference signals.

A switched capacitor arrangement for tuning a differential circuit is disclosed. The switched capacitor arrangement comprises a first node, a second node and a third node. The switched capacitor arrangement further comprises a first capacitor coupled between the first node and the second node, a second capacitor coupled between the second node and the third node, and a first switch branch comprising a first switch coupled between the second node and a signal ground node. The first switch has an on state and an off state. The first node and third node are configured to be connected to respective differential nodes of the differential circuit. The switched capacitor arrangement is configured to tune the differential circuit by controlling the state of the first switch.

Differential electro-mechanical oscillating circuits are described. These circuits may be used in a variety of contexts to produce differential oscillating signals, such as sine waves or square waves. A switched capacitor circuit (SCC) is used to prevent low-frequency locking, whereby the output of the resonator would otherwise lock to a constant value. More specifically, the SCC provides an impedance in parallel to the resonator between the output terminals of oscillating circuit. The SCC is designed so that, at low frequencies, its impedance is lower than the impedance of the resonator. The presence of such an impedance prevents the formation of an open circuit between the output terminals, thus maintaining the oscillating circuit in the oscillation mode. The differential electro-mechanical oscillating circuits described herein may be used to produce clock signals or otherwise to produce periodic reference signals.