Spectral shaping of spread spectrum clocks/frequencies through post processing
AssigneeTexas Instruments Incorporated
InventorJoerg Erik Goller
Life of this patent
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Abstract
An integrated circuit. The integrated circuit comprises a timebase generator and a switch mode direct current-to-direct current (DC-to-DC) converter coupled to the timebase generator. The timebase generator comprises a linear feedback shift register (LFSR) having an output and a logic circuit comprising a first logic inverter, a first AND logic gate, and a first multiplexer, wherein the first logic inverter has an input coupled to a most significant bit of the output of the LFSR, wherein the first AND logic gate has a first input coupled to a second most significant bit of the output of the LFSR and a second input coupled to an output of the first logic inverter, wherein a selector input of the first multiplexer is coupled to an output of the first AND logic gate.
Claims13
A system, comprising:
- an integrated circuit, comprising:
- a timebase generator that comprises a linear feedback shift register (LFSR) configured to output a timebase control word to spread a timebase frequency, a logic circuit having an input coupled to the LFSR and configured to modify selected values of the timebase control word, and a timebase signal generator coupled to the LFSR and to the logic circuit, wherein the timebase signal generator is configured to generate a timebase of the timebase generator based on the timebase control word received from the LFSR and from the logic circuit;
- and
- a switch mode direct current-to-direct current (DC-to-DC) converter coupled to the timebase generator and configured to output a DC power based on the timebase generated by the timebase generator,
- wherein the logic circuit is configured to modify selected values of the timebase control word by inverting a second most significant bit of the timebase control word.
A method of operating a switch mode direct current to direct current (DC-to-DC) converter, comprising:
- outputting a timebase control word from a linear feedback shift register configured to produce a sequence of different timebase control word values, wherein the timebase control word comprises bits;
- receiving the timebase control word by a logic circuit;
- based on a determination by the logic circuit that the timebase control word has a value in a center range of values, shifting the value of the timebase control word by the logic circuit;
- based on a determination by the logic circuit that the timebase control word has a value outside the center range of values, leaving the value of the timebase control word unchanged by the logic circuit;
- outputting the timebase control word by the logic circuit;
- generating a timebase by a timebase signal generator based on the timebase control word output by the logic circuit;
- and
- switching the switch mode DC-to-DC converter based on the timebase.
Dependencies are inferred from the claim text.