Frederick E Martin

US Patent:

6774732, Aug 10, 2004

Filed:

Feb 14, 2003

Appl. No.:

10/367007

Inventors:

David B. Harnishfeger - Chandler AZ
Daniel E. Brueske - Fort Lauderdale FL
Frederick L. Martin - Plantation FL

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

H03L 7085

US Classification:

331 25, 331 1 A, 331 10, 331 14, 331 16

Abstract:

A system for coarsely tuning at least one voltage controlled oscillator (VCO) ( ) in a phase locked loop (PLL) synthesizer ( ) that includes a phase-frequency detector (PFD) for determining a phase difference between a VCO frequency and a reference frequency and providing an error signal if the VCO frequency and reference frequency are at least 2 radians out of phase. A monitor ( ) is then used for tracking the number of error signals produced by the PFD. The free running frequency of the VCO may be coarsely tuned in the event the monitor circuit reaches some predetermined level. The invention offers great advantage in enabling a PLL to be coarsely tuned to enable the PLLs VCO to remain with an operational range despite operational factors that effect circuit operation.