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US 6,969,978 B2Granted
DC-DC converter with reduced electromagnetic interference
AssigneeRF Micro Devices, Inc.
InventorDavid Dening
Life of this patent
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Abstract
A DC-DC converter includes a variable frequency oscillator, a control system and a power train. The DC-DC converter is well suited for use in a cell phone. The control system uses the output of the oscillator to control the power train. The oscillator varies its frequency as a function of a pseudo random number generator, thereby reducing electromagnetic interference caused by ripple in the output of the DC-DC converter.
Claims14
A DC-DC switching power supply, comprising:
- a power train;
- a variable frequency oscillator generating a variable frequency output as a function of a pseudo random number and comprising:
- a pseudo random number generator providing the pseudo random number;
- and
- a digital to analog converter that takes the pseudo random number output by the pseudo random number generator and sets a current level as a function of the pseudo random number;
- and
- a control system adapted to control the power train as a function of the variable frequency output of the variable frequency oscillator.
4 more elements
A DC-DC switching power supply, comprising:
- a power train;
- a variable frequency oscillator having an output and comprising:
- a pseudo random number generator;
- and
- a pair of digital to analog converters adapted to take a pseudo random number output by the pseudo random number generator and set a current level for charging and discharging a capacitor as a function of the pseudo random number;
- and
- a control system adapted to control the power train as a function of the output of the variable frequency oscillator.
4 more elements
A method of operating a DC-DC converter comprising:
- generating a variable frequency output with an oscillator as a function of a pseudo random number, generating the variable frequency output comprising:
- generating the pseudo random number with the pseudo random number generator;
- and
- providing the pseudo random number to a pair of digital to analog converters to set a current level used to charge and discharge a capacitor, thereby generating the variable frequency output as a function of the pseudo random number;
- and controlling a power train as a function of the variable frequency output.
2 more elements
Dependencies are inferred from the claim text.