Embodiments can provide individualized controlling of noise injection during startup of a crystal oscillator. In some embodiments, a simple learning block can be placed in parallel to a crystal oscillator circuit to control noise injection during the startup of the crystal oscillator. The learning block can be configured to control the noise injection during the startup of the crystal oscillator by determining whether the crystal oscillator has been stabilized. In some implementations, an adjustment block may be employed to adjust the count determined by the learning block based on one or more characteristics of the crystal oscillator during a startup of the crystal oscillator. In some embodiments, a simple block that creates a negative capacitance can be configured in parallel to the crystal oscillator.

Embodiments can provide individualized controlling of noise injection during startup of a crystal oscillator. In some embodiments, a simple learning block can be placed in parallel to a crystal oscillator circuit to control noise injection during the startup of the crystal oscillator. The learning block can be configured to control the noise injection during the startup of the crystal oscillator by determining whether the crystal oscillator has been stabilized. In some implementations, an adjustment block may be employed to adjust the count determined by the learning block based on one or more characteristics of the crystal oscillator during a startup of the crystal oscillator. In some embodiments, a simple block that creates a negative capacitance can be configured in parallel to the crystal oscillator.

A circuit device includes a first oscillation circuit, a second oscillation circuit, a clock signal output circuit adapted to output a clock signal based on an output signal of the first oscillation circuit, and an output control circuit adapted to perform output control of the clock signal output circuit. The output control circuit includes a counter circuit adapted to perform a counting process based on an output signal of the second oscillation circuit, and the counter circuit outputs an output enable signal of the clock signal to the clock signal output circuit based on a result of the counting process.

A circuit device includes a first oscillation circuit, a second oscillation circuit, a clock signal output circuit adapted to output a clock signal based on an output signal of the first oscillation circuit, and an output control circuit adapted to perform output control of the clock signal output circuit. The output control circuit includes a counter circuit adapted to perform a counting process based on an output signal of the second oscillation circuit, and the counter circuit outputs an output enable signal of the clock signal to the clock signal output circuit based on a result of the counting process.

An oscillator arrangement is provided, comprising a relaxation oscillator having an active state and an inactive state; a bias current circuit portion arranged to provide a bias current to the relaxation oscillator during said active state; and an electronic switch arranged to isolate said relaxation oscillator from the bias current circuit portion when in said inactive state. The oscillator arrangement is arranged to store an internal voltage value associated with said bias current and the bias current circuit portion is arranged to use the stored internal voltage value to generate the bias current when the oscillator is started up from the inactive state to the active state.

An oscillator arrangement is provided, comprising a relaxation oscillator having an active state and an inactive state; a bias current circuit portion arranged to provide a bias current to the relaxation oscillator during said active state; and an electronic switch arranged to isolate said relaxation oscillator from the bias current circuit portion when in said inactive state. The oscillator arrangement is arranged to store an internal voltage value associated with said bias current and the bias current circuit portion is arranged to use the stored internal voltage value to generate the bias current when the oscillator is started up from the inactive state to the active state.

Methods and apparatus are disclosed to generate an oscillating output signal having a voltage swing greater than a voltage swing across nodes of active devices. An example oscillator includes a tank to generate an oscillating output signal in response receiving an edge of an enable signal; a feedback generator including a first gain stage forming a first feedback loop with the tank, the first feedback loop providing a first charge to maintain the oscillating output signal and a second gain stage forming a second feedback loop with the tank, the second feedback loop providing a second charge to maintain the oscillating output signal, the first and second charges combining with the oscillating output signal to generate a high voltage swing; and an attenuator connected between the tank and the feedback generator to isolate the tank from active components of the feedback generator.

Methods and apparatus are disclosed to generate an oscillating output signal having a voltage swing greater than a voltage swing across nodes of active devices. An example oscillator includes a tank to generate an oscillating output signal in response receiving an edge of an enable signal; a feedback generator including a first gain stage forming a first feedback loop with the tank, the first feedback loop providing a first charge to maintain the oscillating output signal and a second gain stage forming a second feedback loop with the tank, the second feedback loop providing a second charge to maintain the oscillating output signal, the first and second charges combining with the oscillating output signal to generate a high voltage swing; and an attenuator connected between the tank and the feedback generator to isolate the tank from active components of the feedback generator.

An oscillator using a supply regulation loop and a method of operating the oscillator are provided. The oscillator includes a reference voltage generator configured to generate reference voltages from a supply voltage, a supply regulation loop circuit including a first operational amplifier and a transistor, the first operational amplifier being configured to receive a first reference voltage of the reference voltages, and the transistor being connected to an output terminal of the first operational amplifier, and a frequency locked loop (FLL) circuit configured to generate a clock signal, based on an input voltage determined based on a current flowing in the transistor and a second reference voltage of the reference voltages, wherein the first operational amplifier may include an input terminal configured to receive the first reference voltage and to receive negative feedback from the transistor, and the output terminal being configured to generate an output voltage independent of noise of the supply voltage.

An oscillator using a supply regulation loop and a method of operating the oscillator are provided. The oscillator includes a reference voltage generator configured to generate reference voltages from a supply voltage, a supply regulation loop circuit including a first operational amplifier and a transistor, the first operational amplifier being configured to receive a first reference voltage of the reference voltages, and the transistor being connected to an output terminal of the first operational amplifier, and a frequency locked loop (FLL) circuit configured to generate a clock signal, based on an input voltage determined based on a current flowing in the transistor and a second reference voltage of the reference voltages, wherein the first operational amplifier may include an input terminal configured to receive the first reference voltage and to receive negative feedback from the transistor, and the output terminal being configured to generate an output voltage independent of noise of the supply voltage.