Patent · US Expired

Phase locked loop and method for trimming a loop filter

US7180344B2 · kind B2 · utility

4Cited by

9References

22Claims

0Family size

Assignee

Infineon Technologies AG · DE

Inventors

Thomas Mayer · Kolbermoor, DE
Werner Schelmbauer · Linz, AT
Günter Märzinger · Eisenlohrsweg, AT

Key dates

Filing date	Aug 25, 2005
Grant date	Feb 20, 2007
Priority date	—
Expiry date	Aug 25, 2025

Classification

Technology area (CPC H)Electricity
CPC primaryH03L7/1075
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

The invention includes a phase locked loop which has a voltage-controlled oscillator, a phase comparator and a charge pump. The charge pump is coupled to a setting input of the voltage-controlled oscillator via a loop filter. A feedback input of the phase comparator is connected to the output of the voltage-controlled oscillator via a frequency divider, and the phase comparator is designed to output an actuating signal to the charge pump. The loop filter has a first charge store and at least one tunable element that alters a filter characteristic of the loop filter. In addition, there is a trimming circuit which is coupled to the at least one further element in order to alter the filter characteristic of the loop filter and which is designed to compare a time period for a charging operation in a loop filter with a reference time period.

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