Low power wide tuning range oscillator
AssigneeTexas Instruments Incorporated
InventorSudipto Chakraborty
Life of this patent
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Abstract
A wide tuning range oscillator system uses multiple active cores with cross-coupled transistors and multiple tapped inductors having windings that can be connected to circuit nodes. These active cores are connected to a pair of symmetric tapping points and are switched ON/OFF by biasing elements. Biasing schemes and the topology of the individual cross-coupled cores may be different from each other. The tapping points are symmetrically arranged around the center point of the inductor. One or more of the active cores may be enabled for tuning the center frequency of the oscillator system.
Claims15
An oscillator comprising:
- a first oscillator core comprising:
- a first pair of cross-coupled transistors including first and second transistors;
- and
- a first variable resistor coupled to the first pair of cross-coupled transistors;
- and
- a resonator tank comprising a capacitor and a tapping inductor, the tapping inductor having a first symmetrical pair of tapping nodes including first and second tapping nodes, the first tapping node coupled to the first transistor, the second tapping node coupled to the second transistor, the capacitor coupled between the first and second tapping nodes;
- wherein the tapping inductor has differential symmetry and self biasing at a point of symmetry within the tapping inductor;
- wherein when a first signal and a second signal, the first and second signal being opposite in phase, are applied to terminals of the oscillator, an effective AC swing at the point of symmetry is substantially zero.
An oscillator comprising:
- a first oscillator core comprising:
- a first pair of cross-coupled transistors including first and second transistors, the first transistor having a first source, a first gate, and a first drain, the second transistor having a second source, a second gate, and a second drain, wherein the first gate is coupled to the second drain and the second gate is coupled to the first drain;
- and
- a first variable resistor coupled to the first and second sources;
- and
- a resonator tank comprising a capacitor and a tapping inductor, the tapping inductor having a first symmetrical pair of tapping nodes including first and second tapping nodes, the first tapping node coupled to the first drain, the second tapping node coupled to the second drain, the capacitor coupled between the first and second tapping nodes;
- wherein the tapping inductor has differential symmetry and self biasing at a point of symmetry within the tapping inductor;
- wherein when a first signal and a second signal, the first and second signal being opposite in phase, are applied to terminals of the oscillator, an effective AC swing at the point of symmetry is substantially zero.
Dependencies are inferred from the claim text.