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US 11,817,868 B2Granted
Apparatus for digital frequency synthesizer with sigma-delta modulator and associated methods
AssigneeSilicon Laboratories Inc.
InventorJohn M. Khoury
Life of this patent
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Abstract
An apparatus includes a digitally controlled oscillator (DCO), which includes an inductor coupled in series with a first capacitor. The DCO further includes a second capacitor coupled in parallel with the series-coupled inductor and first capacitor, a first inverter coupled in parallel with the second capacitor, and a second inverter coupled back-to-back to the first inverter. The DCO further includes a digital-to-analog-converter (DAC) to vary a capacitance of the first capacitor.
Claims22
An apparatus comprising:
- a sigma-delta modulator (SDM) having three modes of operation;
- wherein an integer (N) is provided as a first input to the SDM;
- wherein an output signal of the SDM toggles between two values derived from the integer (N);
- and wherein a derivation of the two values depends on whether the SDM is operating in a first mode, a second mode, or a third mode of the three modes of operation.
1 more element
An apparatus comprising:
- a sigma-delta modulator (SDM) having a first mode, a second mode, and a third mode of operation;
- wherein a fractional divide parameter (n) is provided as an input to the SDM;
- and wherein a value of the fractional divide parameter (n) determines whether the SDM operates in the first mode, the second mode, or the third mode of operation.
A method of operating a digital frequency synthesizer (DFS), the method comprising;
- generating an output signal from a sigma-delta modulator (SDM) having a first mode, a second mode, and a third mode of operation;
- providing a fractional divide parameter (n) as an input to the SDM;
- and selecting the first mode, the second mode, or the third mode of operation for operation of the SDM according to a value of the fractional divide parameter (n).
Dependencies are inferred from the claim text.