US 8,138,840 B2 · Optimal dithering of a digitally controlled oscillator with clock dithering for gain and bandwidth control

Abstract

A digital phase locked loop (DPLL) and method include an adjustable delay line configured to receive a reference clock as an input and to output a dithered reference clock signal. A phase and frequency detector (PFD) is configured to compare the dithered reference clock signal with a feedback clock signal to determine phase and frequency differences between the dithered reference clock signal and the feedback clock signal. A digitally controlled oscillator (DCO) is configured to receive early or late determinations from the PFD to adjust an output in accordance therewith, wherein the dithered reference clock signal distributes jitter response to enhance overall operation of the DPLL.

Claims23

Dependent claims

A digital phase locked loop (DPLL), comprising:

an adjustable delay line configured to receive at least one of a reference clock and a feedback clock as an input and to output a dithered signal;
a phase and frequency detector (PFD) configured to compare clock signals including a reference clock signal and a feedback clock signal wherein at least one of the clock signals is the dithered signal to determine phase and frequency differences between the clock signals, and further wherein a gain of the PFD is adjusted such that noise power is shaped to higher frequencies beyond a loop bandwidth of the DPLL;
and
a digitally controlled oscillator (DCO) configured to receive early or late determinations from the PFD to adjust an output in accordance therewith, wherein the dithered signal distributes jitter response to enhance overall operation of the DPLL.

1 more element

Dependencies are inferred from the claim text.

Optimal dithering of a digitally controlled oscillator with clock dithering for gain and bandwidth control

Life of this patent

Optimal dithering of a digitally controlled oscillator with clock dithering for gain and bandwidth control

Life of this patent

Abstract

Claims23