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US 2023/0421101 A1Published application
Low power crystal oscillator
AssigneeSTMicroelectronics International N.V.
InventorsAnand KUMAR, Nitin JAIN
Life of this patent
Estimating the term…
Abstract
A low power crystal oscillator circuit having a high power part and a low power part. Oscillation is initialized using the high power part. Once the crystal is under stable oscillation, the circuit switches to the low power part and continue operation for a long duration.
Claims18
A method for operating a low power crystal oscillator circuit, comprising:
- sending a startup signal of a first polarity to a startup terminal of a crystal oscillator circuit having an output terminal and a current supply;
- driving the crystal oscillator circuit with current of a first amperage through a first current mirror having first and second current mirror transistors, the first current mirror transistor having a width to length ratio that is over one hundred times greater than the width to length ratio of the second current minor transistor in the first current mirror, the crystal oscillator circuit configured to output a first voltage value at the output terminal in response to the first amperage;
- maintaining the startup signal of the first polarity at the startup terminal for a first period time;
- reversing the first polarity of the startup signal on the startup terminal to cause the first current mirror to turn off and cease to draw current;
- driving the crystal oscillator circuit with current of a second amperage through the first current mirror;
- and
- drawing current of the second amperage value from the current supply which is J times less than the first amperage and the crystal oscillator circuit outputs voltage of a second voltage value which is K times less than the first voltage value at the output terminal.
4 more elements
A method, comprising:
- coupling a first capacitor to a crystal and a low power supply;
- coupling a first current minor transistor to a high power supply;
- coupling a first current source to the first current mirror transistor;
- coupling the first current source to the low power supply;
- coupling a second current mirror transistor to the high power supply and the first current mirror transistor;
- coupling a first startup control transistor to the second current minor transistor and the crystal;
- coupling a third current minor transistor to the high power supply;
- coupling a second current source to the third current mirror transistor and to the low power supply;
- coupling a fourth current minor transistor to the high power supply and the third current mirror transistor;
- coupling a second startup control transistor to the fourth current mirror transistor and to the crystal;
- and
- coupling a third capacitor to the third and fourth current minor transistors and to the crystal.
9 more elements
A method, comprising:
- coupling a first capacitor to a crystal and a low power supply;
- coupling a first current mirror transistor to a high power supply;
- coupling a first current source to the first current mirror and the low power supply;
- coupling a second current mirror transistor to the high power supply and the first current mirror transistor;
- coupling a first startup control transistor to the second current mirror transistor and the crystal;
- coupling a third current mirror transistor to the high power supply;
- coupling a second current source to the third current mirror transistor and the low power supply.
4 more elements
Dependencies are inferred from the claim text.