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 crystal oscillator includes an inverter configured to receive a first voltage at a first node and output a second voltage at a second node, a stacked-diode feedback network inserted between the first node and the second node, a waveform shaper configured to couple the second node to a third node in accordance with the first voltage, a crystal inserted between a fourth node and a fifth node, wherein the fourth node is coupled to the third node, and the fifth node is coupled to the first node, a first shunt capacitor inserted between the fourth node and a ground node, and a second shunt capacitor inserted between the fifth node to and the ground node.

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.

An oscillation circuit includes a first oscillation circuit configured to oscillate a resonator to generate a first oscillation signal, a second oscillation circuit configured to generate a second oscillation signal, a frequency measurement circuit configured to measure a frequency of the second oscillation signal based on the first oscillation signal in a first period in which the first oscillation circuit is in operation, a holding circuit configured to hold a measurement result by the frequency measurement circuit in a second period in which the first oscillation circuit is not in operation, and an oscillation signal generation circuit configured to generate a third oscillation signal based on the second oscillation signal and the measurement result held in the holding circuit in a third period in which the first oscillation circuit starts up, wherein the third oscillation signal is supplied to the first oscillation circuit in the third period.

A crystal oscillator includes an inverter configured to receive a first voltage at a first node and output a second voltage at a second node, a stacked-diode feedback network inserted between the first node and the second node, a waveform shaper configured to couple the second node to a third node in accordance with the first voltage, a crystal inserted between a fourth node and a fifth node, wherein the fourth node is coupled to the third node, and the fifth node is coupled to the first node, a first shunt capacitor inserted between the fourth node and a ground node, and a second shunt capacitor inserted between the fifth node to and the ground node.

Disclosed is an integrated circuit amplifier for use in a crystal oscillator. The circuit amplifier comprises a transistor; a voltage dependent capacitance circuit; and a node. The voltage dependent capacitance circuit comprises a device with a voltage dependent capacitance and a bias circuit. The node is connected to a terminal of the transistor and the integrated circuit amplifier is configured such that an intrinsic capacitance of the transistor is dependent on the mean voltage at the node. The node is connected to a terminal of the voltage dependent capacitance circuit and the integrated circuit amplifier is configured such that an effective capacitance of the node is dependent on the intrinsic capacitance of the transistor and the voltage dependent capacitance of said device. When in use, the voltage dependent capacitance circuit reduces the amount of change of the effective capacitance of the node when the mean voltage at the node changes.

A crystal oscillator including a feedback circuit, and a reference clock generating circuit including the crystal oscillator. The crystal oscillator is configured to generate an oscillating signal based on a natural frequency of a crystal. The crystal oscillator may include: a current generating circuit connected to a first node having a first voltage and a second node having a second voltage, and configured to output a first current to the second node; a feedback circuit connected to the generating circuit via the first and second nodes and configured to adjust a level of the second voltage by controlling a level of the first voltage; and a crystal circuit connected to the second node and configured to generate the oscillating signal based on the second voltage.

An oscillator includes a resonator, a circuit device that is electrically coupled to the resonator and generates a clock signal, a control terminal that is electrically coupled to the circuit device, and an output terminal that is electrically coupled to the circuit device and outputs the clock signal. The circuit device includes an abnormality detection circuit and sets a potential of the control terminal to an abnormality detection voltage when an abnormal state is detected by the abnormality detection circuit.

An oscillator includes a resonator, a circuit device that is electrically coupled to the resonator and generates a clock signal, and an output terminal that is electrically coupled to the circuit device and outputs the clock signal. The circuit device includes an abnormality detection circuit, and when an abnormal state is detected by the abnormality detection circuit, the circuit device changes a signal characteristic of the clock signal.

An integrated circuit device includes an oscillation circuit that generates an oscillation signal by causing a resonator to oscillate, a temperature compensation circuit that performs temperature compensation of an oscillation frequency of the oscillation circuit, an output circuit that outputs a clock signal based on the oscillation signal, a first regulator that generates a first regulated power supply voltage based on a power supply voltage and supplies the first regulated power supply voltage to the temperature compensation circuit, and a second regulator that generates a second regulated power supply voltage based on the power supply voltage and supplies the second regulated power supply voltage to the output circuit.