Oscillator circuit with two current supplies
AssigneeNordic Semiconductor ASA
InventorFrode Telstø
Life of this patent
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Abstract
An oscillator circuit comprises a crystal oscillator and an inverter. The input of the inverter is connected to the first terminal of the crystal oscillator and the output of the inverter is connected to the second terminal of the crystal oscillator, oscillator circuit is arranged to operate the inverter in its linear operating region. An amplitude regulator has an input connected to the input of the inverter, arranged to provide a first supply current IAREG to the inverter, where the magnitude of the first supply current is inversely dependent on a magnitude of a voltage at the inverter input. A digital-to-analogue converter is arranged to provide a second supply current IDAC to the inverter having a magnitude determined by a digital signal applied to a digital input of the digital-to-analogue converter.
Claims13
An oscillator circuit comprising:
- a crystal oscillator having first and second terminals;
- an inverter having an input terminal and an output terminal, wherein the input terminal of the inverter is connected to the first terminal of the crystal oscillator and the output terminal of the inverter is connected to the second terminal of the crystal oscillator, and wherein the oscillator circuit is arranged to operate the inverter in its linear operating region;
- an amplitude regulator having an input terminal thereof connected to the input terminal of the inverter, arranged to provide a first supply current to the inverter, said first supply current having a magnitude inversely dependent on a magnitude of a voltage at the inverter input terminal, wherein the amplitude regulator is disabled if the magnitude of the voltage at the input terminal of the amplitude regulator is above a threshold value but the amplitude regulator is enabled if the magnitude of the voltage at the input terminal of the amplitude regulator is not above the threshold value;
- and
- a digital-to-analogue converter arranged to provide a second supply current to the inverter having a magnitude determined by a digital signal applied to a digital input of said digital-to-analogue converter.
A method of operating an oscillator circuit comprising:
- a crystal oscillator having first and second terminals;
- an inverter having an input terminal and an output terminal, wherein the input terminal of the inverter is connected to the first terminal of the crystal oscillator and the output terminal of the inverter is connected to the second terminal of the crystal oscillator, and wherein the oscillator circuit is arranged to operate the inverter in its linear operating region;
- an amplitude regulator having an input terminal thereof connected to the input terminal of the inverter, arranged to provide a first supply current to the inverter, wherein the amplitude regulator is disabled if the magnitude of the voltage at the input terminal of the amplitude regulator is above a threshold value but the amplitude regulator is enabled if the magnitude of the voltage at the input terminal of the amplitude regulator is not above the threshold value;
- and
- a digital-to-analogue converter arranged to provide a second supply current to the inverter;
- wherein the method comprises:
- using the amplitude regulator to determine a first supply current;
- varying the magnitude of the first supply current inversely in response to the magnitude of the voltage at the input terminal of the amplitude regulator;
- using the digital-to-analogue converter to determine a second supply current;
- and
- varying the magnitude of the second supply current in response to a digital signal applied to a digital input of said digital-to-analogue converter.
Dependencies are inferred from the claim text.