Disclosed is a differential relaxation oscillator using a differential structure that may stably maintain a differential voltage swing of capacitors despite an influence of an offset voltage and 1/f noise of a comparator, and also generate a dynamic current only at a point in time at which switching is performed, thereby minimizing power consumption.

In some embodiments, the present disclosure relates to a frequency generator having a resistor network and a capacitor network. The capacitor network has a plurality of capacitors connected in parallel with one another. A comparator is configured to output an oscillating voltage signal. An input of the comparator is connected to the output of the resistor network and the output of the capacitor network. A frequency testing circuit is configured to calculate a frequency of the oscillating voltage signal and determine whether the frequency is within a range of an expected frequency. The frequency testing circuit may also be configured to selectively connect a first plate of the plurality of capacitors to a non-varying voltage or to the input of the capacitor network to adjust a frequency of the oscillating voltage signal.

In some embodiments, the present disclosure relates to a frequency generator having a resistor network and a capacitor network. The capacitor network has a plurality of capacitors connected in parallel with one another. A comparator is configured to output an oscillating voltage signal. An input of the comparator is connected to the output of the resistor network and the output of the capacitor network. A frequency testing circuit is configured to calculate a frequency of the oscillating voltage signal and determine whether the frequency is within a range of an expected frequency. The frequency testing circuit may also be configured to selectively connect a first plate of the plurality of capacitors to a non-varying voltage or to the input of the capacitor network to adjust a frequency of the oscillating voltage signal.

A hybrid pulse-width control circuit is provided that includes a ramp voltage generator for generating a ramp voltage signal. A clock pulse generator asserts an output clock signal responsive to the ramp voltage signal equaling a reference voltage.

A RC oscillator comprises a resistor unit. The resistor unit can comprise at least one set of compensation resistor. Each set of compensation resistor comprises a positive temperature coefficient resistor and a negative temperature coefficient resistor coupled in series with the positive temperature coefficient resistor.

An oscillator produces an oscillator output signal usable as a clock signal, otherwise as a frequency reference on an integrated circuit. The oscillator includes an RC network with a voltage-controlled element, such as a voltage-controlled resistor, voltage-controlled capacitor or a combination including a voltage-controlled resistor and voltage-controlled capacitor. Also, a tunable element having an adjustable resistance determined by a first static parameter is included in the RC network. The oscillator also includes a feedback circuit which can include a frequency-to-voltage converter. The feedback circuit generates a control signal for the voltage-controlled element. The feedback circuit includes a feedback reference circuit having a reference output determined by a second static parameter, and a loop amplifier responsive to the reference output and the oscillator output signal.

An oscillator produces an oscillator output signal usable as a clock signal, otherwise as a frequency reference on an integrated circuit. The oscillator includes an RC network with a voltage-controlled element, such as a voltage-controlled resistor, voltage-controlled capacitor or a combination including a voltage-controlled resistor and voltage-controlled capacitor. Also, a tunable element having an adjustable resistance determined by a first static parameter is included in the RC network. The oscillator also includes a feedback circuit which can include a frequency-to-voltage converter. The feedback circuit generates a control signal for the voltage-controlled element. The feedback circuit includes a feedback reference circuit having a reference output determined by a second static parameter, and a loop amplifier responsive to the reference output and the oscillator output signal.

In a described example, an apparatus includes: a capacitor coupled to receive a current at a first terminal and having a second terminal coupled to ground; a first comparator coupled to a voltage at the first terminal of the capacitor and to a first reference voltage; a second comparator coupled to the voltage at the first terminal of the capacitor and to a second reference voltage that is different from the first reference voltage, and having an enable input coupled to the output of the first comparator; a discharge circuit coupled to the capacitor and enabled by the output of the second comparator; and a toggle circuit coupled to the output of the second comparator. Methods are disclosed.

In a described example, an apparatus includes: a capacitor coupled to receive a current at a first terminal and having a second terminal coupled to ground; a first comparator coupled to a voltage at the first terminal of the capacitor and to a first reference voltage; a second comparator coupled to the voltage at the first terminal of the capacitor and to a second reference voltage that is different from the first reference voltage, and having an enable input coupled to the output of the first comparator; a discharge circuit coupled to the capacitor and enabled by the output of the second comparator; and a toggle circuit coupled to the output of the second comparator. Methods are disclosed.

Various implementations described herein are directed to an integrated circuit. The integrated circuit may include a comparator stage, a resistor, a capacitor, and active switches arranged to provide a clock signal having a time period that is independent of a first source voltage. Independence may be achieved by using a second source voltage derived from the first source voltage as a fixed ratio.