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US 2007/0182611 A1Published application
Sigma-delta modulation with minimized noise and fractional-N phase-locked loop including the same
AssigneeSamsung Electronics Co., Ltd.
InventorHwa-Yeal Yu
Life of this patent
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Abstract
A sigma-delta modulator (SDM) includes a delay circuit and an operation circuit. The delay circuit generates multiple clock signals with different delays. The operation circuit includes a plurality of operation stages that operate with timing according to all of the clock signals for high-order sigma-delta modulation. Thus, noise may be dispersed for minimizing noise coupling. The SDM is used to particular advantage within a fractional-N phase-locked loop.
Claims20
A sigma-delta modulator (SDM) comprising:
- a delay circuit that generates a plurality of clock signals, each clock signal having a respective unique delay from a reference clock signal;
- and
- an operation circuit including a plurality of operation stages that operate with timing according to all of the clock signals for high-order sigma-delta modulation.
A method of performing high-order sigma-delta modulation, comprising:
- generating a plurality of clock signals, each clock signal having a respective unique delay from a reference clock signal;
- and
- operating a plurality of operation stages that together perform high-order sigma-delta modulation with timing according to all of the clock signals.
A fractional-N phase-locked loop (PLL) comprising:
- a phase-frequency detector (PFD) that determines a phase difference between a reference frequency signal and a division frequency signal obtained by frequency division of an output frequency signal of the PLL by a division ratio;
- a voltage-controlled oscillator (VCO) that generates the output frequency signal depending on said phase difference;
- and
- a sigma-delta modulator (SDM) for generating the division ratio from a fractional input, the SDM including a plurality of operation stages that operate with timing according to a plurality of clock signals having different delays for high-order sigma-delta modulation.
1 more element
Dependencies are inferred from the claim text.