Phase noise filter for oscillator circuitry
AssigneeApple Inc.
InventorOmar E Elaasar
Life of this patent
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Abstract
An electronic device may include wireless circuitry having an oscillator. The oscillator can include a first transistor having a source-drain terminal coupled to a tail node, a second transistor having a source-drain terminal coupled to the tail node, a first coil having a first terminal coupled to the tail node and having a second terminal coupled to a power supply line, and a second coil inductively coupled to the first coil. The first and second coils can be part of a balun. The balun can be coupled to a tunable capacitance. The tunable capacitance can include multiple differential switchable capacitor circuits. The balun and the tunable capacitance can form a balun phase noise filter configured to reduce a phase noise associated with the oscillator.
Claims19
Circuitry comprising:
- a first transistor having a first source-drain terminal coupled to a tail node;
- a second transistor having a first source-drain terminal coupled to the tail node;
- load components coupled to a second source-drain terminal of the first transistor and a second source-drain terminal of the second transistor;
- a first coil having a first terminal coupled to the tail node and having a second terminal coupled to a power supply line;
- a second coil inductively coupled to the first coil;
- and
- a tunable capacitor connected to the second coil.
Oscillator circuitry comprising:
- a first transistor having a drain terminal coupled to a first output terminal;
- a second transistor having a drain terminal coupled to a second output terminal, an oscillating signal being produced at the first and second output terminals;
- and a balun that includes a first coil having a first terminal coupled to source terminals of the first and second transistors and a second coil having a center tap terminal coupled to a power supply line.
Oscillator circuitry comprising:
- a first transistor having a first source-drain terminal coupled to a first output terminal;
- a second transistor having a first source-drain terminal coupled to a second output terminal;
- a load inductor coupled across the first and second output terminals;
- a tunable load capacitor coupled across the first and second output terminals;
- and a balun phase noise filter configured to reduce a phase noise associated with the oscillator circuitry and including a first coil having a first terminal coupled to the first and second transistors and a second terminal directly coupled to a ground line.
Dependencies are inferred from the claim text.