Chopped oscillator
AssigneeAnalog Devices Technology
InventorAdam GLIBBERY
Life of this patent
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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.
Claims27
A relaxation oscillator, comprising:
- a capacitor;
- a current generator including a chopped current mirror and a chopped current source, providing a charging current and a discharging current to the capacitor;
- a comparator providing a clock signal based on comparison of the capacitor voltage and a threshold voltage;
- and
- a clock divider that divides the clock signal by half to generate a chop signal for the chopped current mirror and the chopped current source.
A relaxation oscillator, comprising:
- a capacitor;
- a current generator providing a charging current and a discharging current to the capacitor;
- a trigger voltage generator including a first voltage source to provide a first trigger voltage and a chopped resistive mirror to provide a second trigger voltage;
- a comparator providing a clock signal based on comparison of the capacitor voltage and one of the first and second trigger voltages;
- and
- a clock divider that divides the clock signal by half to generate a chop signal to control the chopped resistive mirror.
A relaxation oscillator, comprising:
- a capacitor;
- a current generator providing a charging current and a discharging current to the capacitor;
- a trigger voltage generator providing a first trigger voltage and a second trigger voltage;
- a comparator providing a clock signal based on comparison of capacitor voltage and the first and second trigger voltages;
- a current controller including a first current source, a second current source and a chop circuit coupling one of the current sources to the current generator and coupling the other current source to the trigger voltage generator;
- and
- a clock divider that divides the clock signal by half to generate a chop signal for controlling the chop circuit.
A chopped amplifier, comprising:
- a chopped differential amplifier including a plurality of switches to switch two input signals provided to inputs of the chopped differential amplifier, in each phase of a chop signal;
- and
- a source follower circuit receiving a signal from the chopped differential amplifier and providing an output signal.
A method for providing a clock, comprising:
- providing a charging current and a discharging current to a capacitor;
- providing a plurality of trigger voltages;
- providing a clock signal based on comparison of capacitor voltage and a respective trigger voltage, wherein one of the charging current, the discharging current and the trigger voltages includes an error source that causes a change in period of the clock signal;
- and
- adjusting the period of the clock signal to compensate for change in the period due to the error source in an opposite direction on the alternating cycles.
The method of claim 24, wherein the period is adjusted in an opposite direction of the direction caused by the error source.
Dependencies are inferred from the claim text.