An oscillator includes a resonator, a temperature control element that controls a temperature of the resonator, a first temperature sensing element that outputs a first temperature detection signal, a second temperature sensing element that is provided at a position farther from the resonator than the first temperature sensing element and outputs a second temperature detection signal, an analog/digital conversion circuit that converts the first temperature detection signal into a first temperature code which is a digital signal, and converts the second temperature detection signal into a second temperature code which is a digital signal, and a digital signal processing circuit that generates a temperature control code for controlling the temperature control element based on the first temperature code and the second temperature code.

A circuit for generating temperature-stable clocks including first and second crystal oscillators, an input for a reference clock source, a clock output, a first phase acquisition circuit coupled to the first and second crystal oscillators, a second phase acquisition circuit coupled to the input for the reference clock source and to the second crystal oscillator, a first DPLL coupled to the first phase acquisition circuit, a crystal oscillator variation estimator coupled to the first DPLL, a second DPLL coupled to the second phase acquisition circuit and including a phase-frequency detector having a input coupled to the second phase acquisition circuit, a loop filter, a frequency subtractor having an input coupled to the loop filter and an input coupled to the crystal oscillator variation estimator, and a DCO coupled to the frequency subtractor and driving an input of the phase-frequency detector.

A circuit apparatus includes an oscillation circuit that causes a resonator to oscillate to produce an oscillation signal, an oven control circuit that controls a heater provided in correspondence with the resonator, a non-volatile memory that stores control data, a holding circuit that holds the control data transferred from the non-volatile memory, and a processing circuit that carries out a process based on the control data held in the holding circuit. After a power source voltage is supplied, the processing circuit carries out the process of transferring the control data from the non-volatile memory to the holding circuit, and after the transfer of the control data is completed, the processing circuit causes based on a data transfer end signal the oven control circuit to start operating.

An oscillator includes a first container, a second container accommodated in the first container, a resonator element accommodated in the second container, a temperature sensor accommodated in the second container, a first circuit element that is accommodated in the second container and includes an oscillation circuit that causes the resonator element to oscillate so as to generate an oscillation signal on which temperature compensation is performed based on a detected temperature of the temperature sensor, and a second circuit element which is accommodated in the first container and includes a frequency control circuit that controls a frequency of the oscillation signal. The second container and the second circuit element are spaced from each other and are disposed to overlap each other in plan view.

An LC oscillator has a tank driver connected to cause a matched-resistance LC tank to oscillate. The LC tank has an inductor leg in parallel with a capacitor leg. The inductor leg has an explicit inductor having an implicit resistance level R.sub.L. The capacitor leg has an explicit capacitor having an implicit resistance level R.sub.C connected in series with an explicit resistor having an explicit resistance level R.sub.R, where R.sub.M=(R.sub.C+R.sub.R) is substantially equal to R.sub.L. The LC oscillator may have a non-trimmable LC tank and be part of a temperature-compensated frequency reference generator having standalone frequency adjustment circuitry that offers better than 0.1% frequency accuracy (after single trim and batch calibration) over process, voltage, and temperature variations, and lifetime, which can serve as a low-cost replacement for a crystal oscillator for many applications.

A watch includes a chargeable power supply, a crystal oscillation circuit including a crystal oscillator and an oscillation circuit and configured to stop oscillating when a power supply voltage falls below an oscillation stop voltage and to start oscillating when the power supply voltage exceeds an oscillation start voltage, which is higher than the oscillation stop voltage, and a divider circuit that outputs a reference signal by dividing an oscillation signal output from the oscillation circuit. The watch also includes a temperature compensation circuit that performs a temperature compensation function operation that compensates for variation of the reference signal due to a temperature, a first voltage detection circuit that detects that the power supply voltage exceeded a first voltage that is set higher than the oscillation start voltage, and a control circuit that starts the temperature compensation function operation of the temperature compensation circuit when the first voltage detection circuit detects that the power supply voltage exceeded the first voltage, and subsequently continues the temperature compensation function operation even when the power supply voltage falls below the first voltage.

An oscillator includes a first container that includes a first base substrate and a first lid bonded to the first base substrate and has a first internal space, a second container that is accommodated in the first internal space and fixed to the first base substrate, a resonator element that is accommodated in the second container, a temperature sensor that is accommodated in the second container, a first circuit element that is accommodated in the second container and includes an oscillation circuit oscillating the resonator element and generating an oscillation signal on which temperature compensation is performed based on a detected temperature of the temperature sensor, and a second circuit element that is fixed to the first base substrate and includes a frequency control circuit that controls a frequency of the oscillation signal, in which the second container and the second circuit element are arranged side by side in plan view.

A MEMS resonator system has a micromechanical resonant structure and an electronic processing circuit including a first resonant loop that excites a first vibrational mode of the structure and generates a first signal at a first resonance frequency. A compensation module compensates, as a function of a measurement of temperature variation, a first variation of the first resonance frequency caused by the temperature variation to generate a clock signal at a desired frequency that is stable relative to temperature. The electronic processing circuit further includes a second resonant loop, which excites a second vibrational mode of the structure and generates a second signal at a second resonance frequency. A temperature-sensing module receives the first and second signals and generates the measurement of temperature variation as a function of the first variation of the first resonance frequency and a second variation of the second resonance frequency caused by the temperature variation.

In an embodiment, an integrated circuit includes: a switched capacitor coupled between a supply voltage node and a divider node, where a thermistor external to the integrated circuit is to couple to the divider node; an analog-to-digital converter (ADC) coupled to the divider node to receive a voltage at the divider node and generate a digital value based thereon; and a controller coupled to the ADC to determine a temperature associated with the thermistor based at least in part on the digital value.

Techniques are described for post-compensation of frequency drift due to changes in crystal oscillator temperature during operation. For example, a clock system is coupled with a crystal oscillator, and can use a reference clock signal from the crystal oscillator to generate an output clock signal using a clock generator. The clock system can monitor an electrical characteristic of a thermal component integrated with the oscillator, which it can map deterministically to a thermal value indicating a temperature of a crystal component of the oscillator. The clock system can then map the temperature deterministically to a frequency shift of the oscillator away from a nominal value. The clock system can then generate a post-compensation signal that directs the clock generator to shift the frequency of the clock output signal so as to compensate for at least a portion of the frequency drift.