Low noise voltage-controlled oscillator
AssigneeMarvell International Ltd.
InventorsLi Lin, Thomas B. Cho
Life of this patent
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Abstract
Oscillator circuits for reducing phase noise are described in this disclosure. In one embodiment, an oscillator circuit includes a pair of cross-coupled transistors, including a first transistor and a second transistor, a first inductor in communication with a control terminal of the first transistor and an output terminal of the second transistor, a second inductor in communication with a control terminal of the second transistor and an output terminal of the first transistor, and a tank circuit in communication with the first inductor and the second inductor, where the tank circuit comprises a tank inductor and a variable capacitor.
Claims34
An oscillator circuit comprising:
- a first pair of cross-coupled transistors having a first metal oxide semiconductor (MOS) transistor and a second MOS transistor;
- a second pair of cross-coupled transistors having a third MOS transistor and a fourth MOS transistor, wherein a first pair of control terminals of the first MOS and third MOS transistors are coupled together, and a second pair of control terminals of the second MOS and fourth MOS transistors are coupled together;
- a first inductor in communication with the first pair of control terminals of the first MOS and third MOS transistors and a second pair of output terminals of the second MOS and fourth MOS transistors;
- a second inductor in communication with the second pair of control terminals of the second MOS and fourth MOS transistors and a first pair of output terminals of the first MOS and third MOS transistors;
- and
- a tank circuit at least one of coupled between the first pair of control terminals and the first pair of output terminals and coupled between the second pair of control terminals and the second pair of output terminals, wherein the tank circuit comprises a tank inductor and a variable capacitor.
An oscillator circuit comprising:
- a pair of cross-coupled transistors, including a first transistor and a second transistor;
- a first inductor in communication with a control terminal of the first transistor and an output terminal of the second transistor;
- a second inductor in communication with a control terminal of the second transistor and an output terminal of the first transistor;
- and
- a tank circuit in communication with the first inductor and the second inductor, wherein the tank circuit comprises a tank inductor and a variable capacitor,
- wherein outputs of the first and second transistors are outputs of the oscillator circuit, and
- wherein said tank circuit is at least one of coupled between the control terminal of the first transistor and the output terminal of the second transistor and coupled between the control terminal of the second transistor and the output terminal of the first transistor.
A method for operating an oscillator circuit having a first transistor and a second transistor forming a cross-coupled pair of transistors, comprising:
- coupling a first inductor between a control terminal of the first transistor and an output terminal of the second transistor;
- coupling a second inductor between a control terminal of the second transistor and an output terminal of the first transistor;
- coupling a tank circuit between the first inductor and the second inductor, wherein the tank circuit comprises a tank inductor and a variable capacitor, and wherein the tank circuit enables a first mutual inductance between the first inductor and the tank inductor, and enables a second mutual inductance between the tank inductor and the second inductor, and
- directly coupling at least one of a supply voltage and a source current to input terminals of the first and second transistors.
A system for generating a pair of differential output signals with an oscillating circuit having a first transistor and a second transistor forming a cross-coupled pair of transistors, comprising:
- a first inductive means for inductively coupling a control terminal of the first transistor to an output terminal of the second transistor;
- a second inductive means for inductively coupling a control terminal of the second transistor to an output terminal of the first transistor;
- and
- a third inductive means for inductively coupling the first inductive means to the second inductive means, wherein the third inductive means enables mutual inductances between the first inductive means and the second inductive means, and
- wherein a power source is directly coupled to output terminals of said first and second transistors.
A method for operating an oscillator circuit having a first transistor and a second transistor forming a cross-coupled pair of transistors, comprising:
- coupling a first inductor between a control terminal of the first transistor and an output terminal of the second transistor;
- coupling a second inductor between a control terminal of the second transistor and an output terminal of the first transistor;
- coupling a tank circuit between the first inductor and the second inductor, wherein the tank circuit comprises a tank inductor and a variable capacitor and wherein the tank circuit enables a first mutual inductance between the first inductor and the tank inductor, and enables a second mutual inductance between the tank inductor and the second inductor;
- directly coupling at least one of a supply voltage and a source current to input terminals of the first and second transistors;
- and
- coupling the first and second inductors and the tank inductor directly in series.
Dependencies are inferred from the claim text.