Patent · US Expired

Post-filtered delta sigma for controlling a phase locked loop modulator

US6047029A · kind A · utility

21Cited by

11References

14Claims

0Family size

Assignee

Telefonaktiebolaget LM Ericsson (Publ) · SE

Inventors

Håkan Eriksson · Täby, SE
Kjell Gustafsson · Lund, SE
Paul W. Dent · Stehag, SE

Key dates

Filing date	Sep 16, 1997
Grant date	Apr 4, 2000
Priority date	—
Expiry date	Sep 16, 2017

Classification

Technology area (CPC H)Electricity
CPC primaryH04L27/2017
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

A frequency synthesizer has a phase locked loop, a .DELTA..SIGMA. modulator, and a filter. The phase locked loop includes a frequency divider that controls the frequency of the phase locked loop output signal. The output of the .DELTA..SIGMA. modulator is fed through the filter and the output of the filter is used to control a division factor in the frequency divider. Compensation may be performed at the input to the .DELTA..SIGMA. modulator in order to compensate for the filtering performed between the .DELTA..SIGMA. modulator and the frequency divider. The filter may be used to reduce quantization noise in an input to the frequency divider, and thereby reduces phase noise in an output of the phase locked loop.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.