LC oscillator with wide tuning range and low phase noise
First Claim
Patent Images
1. A system comprising:
- at least one adjusting circuit operably coupled to an oscillator, wherein the adjusting circuit comprises;
a resistor;
a reactive element;
a first switch, wherein the first switch is electrically connected to the reactive element and couples and decouples the reactive element to an output of the oscillator based on a control signal, and wherein the resistor provides a bias voltage to the reactive element so that the reactive element has a bias voltage when the first switch is open; and
a second switch, wherein the second switch couples the resistor to the bias voltage based on the control signal when the first switch decouples the reactive element and the second switch decouples the resistor from the bias voltage when the first switch couples the reactive element.
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Abstract
A voltage-controlled oscillator including an active oscillator circuit, an inductor, and capacitive circuits is disclosed. The capacitive circuits are selectively turned on and off to control the frequency of the voltage-controlled oscillator. Particularly, the inductor and the capacitors in the capacitive circuits form LC circuits that provide feedback to the active oscillator circuit. To avoid damage to the switches in the capacitive circuits, the capacitive circuits further comprise resistors. The resistors can be configured in several different ways so that the voltage-controlled oscillator can have a high degree of reliability, and a wide tuning range with constant phase noise performance.
48 Citations
50 Claims
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1. A system comprising:
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at least one adjusting circuit operably coupled to an oscillator, wherein the adjusting circuit comprises;
a resistor;
a reactive element;
a first switch, wherein the first switch is electrically connected to the reactive element and couples and decouples the reactive element to an output of the oscillator based on a control signal, and wherein the resistor provides a bias voltage to the reactive element so that the reactive element has a bias voltage when the first switch is open; and
a second switch, wherein the second switch couples the resistor to the bias voltage based on the control signal when the first switch decouples the reactive element and the second switch decouples the resistor from the bias voltage when the first switch couples the reactive element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus comprising:
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an active oscillator, wherein the active oscillator comprises a first output node and a second output node;
an inductor, wherein the inductor couples the first output node and the second output node; and
at least one capacitive circuit coupled to either the first output node or the second output node, the at least one capacitive circuit comprising a capacitor;
a resistor; and
a first switch, wherein the resistor provides a bias voltage to the capacitor when the first switch is open and wherein the first switch is in series with the capacitor and couples and decouples the capacitor to the output of the oscillator, wherein the capacitor couples the first switch to either the first or second output node, the first switch couples the capacitor to a ground voltage level, and the resistor is coupled to the capacitor and the first switch at a common node of the capacitor and first switch. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for adjusting an oscillator, the method comprising:
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providing a bias voltage via a resistor to a reactive element so that the reactive element has a bias voltage when a first switch is open;
using the first switch to couple and decouple the reactive element to an output of oscillator based on a control signal, thereby adjusting the frequency of the oscillator;
coupling the resistor to the bias voltage via a second switch when the first switch decouples the reactive element; and
decoupling the resistor from the bias voltage via the second switch when the first switch couples the reactive element.
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18. A system comprising:
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at least one adjusting circuit operably coupled to an oscillator, wherein the adjusting circuit comprises;
a resistor;
a reactive element;
a first switch, wherein the first switch is electrically connected to the reactive element and couples and decouples the reactive element to an output of the oscillator, wherein the resistor provides a bias voltage to the reactive element so that the reactive element has a bias voltage when the first switch is open, wherein the bias voltage is generated from a resistor divider and ranges from a ground voltage to a supply voltage. - View Dependent Claims (19, 20)
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21. An apparatus comprising:
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an active oscillator including a first and second output nodes;
an inductor coupled between the first and second output nodes; and
at least one capacitive circuit coupled to either the first output node or the second output node, the at least one capacitive circuit comprising;
a capacitor;
a resistor; and
a first switch,wherein the resistor provides a bias voltage to the capacitor when the first switch is open, wherein the first switch is electrically connected to the capacitor and couples and decouples the capacitor to the output of the oscillator based on a control signal, and wherein the at least one capacitive circuit comprises a second switch and the second switch couples and decouples the resistor to the bias voltage. - View Dependent Claims (22, 23, 49)
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24. An apparatus, comprising:
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at least one reactive element;
a first switch circuit to selectively couple the reactive element to an output of an oscillator based on a control signal; and
a second switch circuit to couple the reactive element to a bias voltage when the first switch circuit decouples the reactive element from the oscillator output, wherein the reactive element tunes an output frequency of the oscillator output when the first switch couples the reactive element to the oscillator. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 50)
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37. A method, comprising:
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operating a first switch circuit to couple a reactive element to an output of an oscillator based on a control signal; and
operating a second switch circuit to couple the reactive element to a bias voltage when the first switch circuit decouples the reactive element from the oscillator output, wherein the reactive element tunes an output frequency of the oscillator when the reactive element is coupled to the oscillator output. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48)
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Specification