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US 9,054,690 B2Granted
Chopped oscillator
AssigneeAnalog Devices Global
InventorAdam Glibbery
Life of this patent
Estimating the term…
Abstract
Embodiments of the present disclosure may provide a relaxation oscillator with improved performance against phase noise error. The phase noise error may be reduced from sources whose power is greater at lower frequencies. To reduce the noise error, the relaxation oscillator may include chopping in the charging current driver; chopping in the trigger level generator; and/or chopping in the currents that feed the cells. A chopped amplifier may be provided to perform chopping of the input signals.
Claims18
A relaxation oscillator, comprising:
- a current controller;
- a capacitor;
- a current generator, coupled to the current controller and the capacitor, providing a charging current and a discharging current to the capacitor to generate a capacitor voltage;
- a trigger voltage generator, coupled to the current controller, providing a threshold voltage;
- a comparator providing a clock signal based on comparison of the capacitor voltage and the threshold voltage;
- a plurality of chopping circuits performing current mirroring operations that average low frequency noise generated respectively in the current controller, the current generator, and the trigger voltage generator;
- and
- a clock divider that divides the clock signal by half to generate a chop signal for the plurality of chopping circuits.
5 more elements
A method for providing a clock, comprising:
- providing a plurality of source currents;
- based on at least one of the plurality of source currents, providing a charging current and a discharging current to a capacitor to generate a capacitor voltage;
- generating a plurality of trigger voltages;
- comparing the capacitor voltage and a respective trigger voltage;
- generating a clock signal based on the comparison, wherein the source currents, charging current, the discharging current and the trigger voltages include a respective error source that causes a change in period of the clock signal;
- performing current mirroring operations that average low frequency noise generated in the error sources;
- and
- adjusting the period of the clock signal to compensate for change in the period due to the error sources in an opposite direction on the alternating cycles.
5 more elements
A circuit, comprising:
- a current controller;
- a capacitor;
- a current generator, coupled to the current controller and the capacitor, to generate a charging current and a discharging current to the capacitor;
- a trigger voltage generator, coupled to the current controller, to generate a plurality of trigger voltages;
- a comparator to provide a clock signal based on comparison of capacitor voltage and a respective trigger voltage, wherein the current controller, the current generator, and the trigger voltage generator include error sources that causes a change in period of the clock signal;
- means for performing current mirroring operations that average low frequency noise generated in the error sources and adjusting the period of the clock signal to compensate for change in the period due to the error sources in an opposite direction on the alternating cycles.
3 more elements
Dependencies are inferred from the claim text.