An apparatus includes a temperature measuring device within a thermally conductive package. A crystal within the package is thermally coupled to the temperature measuring device and subjected to a same temperature as the temperature measuring device. A controller external to the package is configured to receive a signal from the crystal and a temperature measurement from the temperature measuring device. The controller is configured to estimate a frequency error of the crystal based on the temperature measurement and to provide a frequency error estimate to an external system.

A semiconductor device includes a mode determination unit configured to determine a power mode based on a temperature of the semiconductor device and a reference temperature, the power mode including one of a first mode which sets the operating frequency of the operation clock to be a first operating frequency and a second mode which sets the operating frequency of the operation clock to be a second operating frequency, and output a control signal according to the power mode to a clock generating unit.

Systems and processes disclosed herein determine the temperature of a crystal, such as a crystal that may be used in a crystal oscillator, using the reference crystal itself. The system can measure the temperature of the crystal without a temperature sensor. Further, a single oven technique may be used to maintain the temperature of the reference crystal. Thus, in certain embodiments, a more compact crystal oscillator can be generated compared to conventional techniques. Further, by measuring the reference crystal based on signals generated by the reference crystal itself, the system disclosed herein is more accurate than many previous crystal oscillator systems.

A timing signal generation device includes a PLL circuit that synchronizes a first clock signal of an atomic oscillator with a reference timing signal of a GPS receiver, a PLL circuit that synchronizes a second clock signal of an oven-controlled crystal oscillator with the first clock signal, a first count reset unit that enables resetting of a count value of a divider in the PLL circuit when an operation of the PLL circuit is restarted, and a second count reset unit that enables resetting of a count value of a divider in the PLL circuit when the operation of the PLL circuit is restarted.

A voltage controlled oscillator implements optimising its effective frequency versus voltage transfer function by generating and applying a frequency control signal via a function having a plateau region and a higher slope region, where a horizontal position of the higher slope region, a slope value in the higher slope region, and a function value change magnitude over the higher slope region are adjustable.

Hysteresis causes the temperature dependent frequency characteristic of the crystal of a crystal oscillator to be different when the temperature is rising from a previous colder state and when the temperature is falling from a hotter state. A rising temperature-to-frequency mapping polynomial and a falling temperature-to-frequency mapping polynomial are generated and their evaluations are weighted based on a current temperature and past temperature(s). The weighted evaluations are combined and used in temperature-based frequency compensation of the crystal oscillator.

Increases of circuit scale and power consumption are suppressed while frequency deviation is kept within a predetermined allowable range. A semiconductor device according to an embodiment includes a variable load capacity circuit including a plurality of load capacity elements coupled in parallel to one end of a crystal resonator and a plurality of switches that are respectively serially coupled to the load capacity elements, and a switch control unit that controls ON/OFF of the switches on the basis of information to be an index of frequency deviation due to temperature change of a frequency signal obtained by oscillating the crystal resonator. The switch control unit changes the number of switches that will be turned ON among the plurality of switches so that an absolute value of the frequency deviation becomes small when the information is not included in a predetermined allowable range.

A temperature compensated crystal oscillator implements temperature compensation by generating and applying a temperature compensation signal via a function having a plateau region and a higher slope region, where a horizontal position of the higher slope region, a slope value in the higher slope region, and a function value change magnitude over the higher slope region are adjustable.

A temperature compensated oscillation controller includes a temperature compensation circuit configured to provide a reference voltage through a first terminal and to receive an input voltage including temperature information through a second terminal, and an oscillation circuit configured to be connected to an external crystal resonator through third and fourth terminals and to output a clock signal in response to an oscillation signal from the external crystal resonator. The temperature compensation circuit is configured to perform a voltage controlled oscillator-based sensing operation to convert the input voltage into a temperature code and to adjust a frequency of the clock signal using the temperature code.

A stress compensated oscillator circuitry comprises a sensor arrangement for providing a sensor output signal S.sub.Sensor, wherein the sensor output signal S.sub.Sensor is based on an instantaneous stress or strain component in the semiconductor substrate, a processing arrangement for processing the sensor output signal S.sub.Sensor and providing a control signal S.sub.Control depending on the instantaneous stress or strain component in the semiconductor substrate, and an oscillator arrangement for providing an oscillator output signal S.sub.osc having an oscillator frequency f.sub.osc based on the control signal S.sub.Control, wherein the control signal S.sub.Control controls the oscillator output signal S.sub.osc, and wherein the control signal S.sub.Control reduces the influence of the instantaneous stress or strain component in the semiconductor substrate onto the oscillator output signal S.sub.osc, so that the oscillator circuitry provides a stress compensated oscillator output signal.