Patent · US Active

System and method for an automatic coarse tuning of a voltage controlled oscillator in a phase-locked loop (PLL)

US7808288B2 · kind B2 · utility

5Cited by

7References

8Claims

0Family size

Assignee

STMICROELECTRONICS, INC. · US

Inventor

Kallol Chatterjee · Noida, IN

Key dates

Filing date	Dec 28, 2007
Grant date	Oct 5, 2010
Priority date	—
Expiry date	Dec 8, 2028

Classification

Technology area (CPC H)Electricity
CPC primaryH03B2200/005
WIPO fieldBasic communication processes
WIPO sectorElectrical engineering

Abstract

Circuits and methods for an automatic coarse tuning in a phase locked loop (PLL) include observing a variation in a control voltage to disable a fine loop and to enable a coarse loop as the control voltage departs from a specified range. The circuit includes the fine loop, the coarse loop, and a control circuit. The fine loop includes a phase frequency detector (PFD), a charge pump, a loop filter, a VCO and a divider. The coarse loop includes a frequency detector, an up counter, a down counter, and an LC VCO. The control circuit includes a bandgap module, a comparator and other circuits such as a lock detect circuit. The control circuit is used to switch between the coarse loop and the fine loop.

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