Digital phase locked loop for different frequency bands

US6445252B1 · kind B1 · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Jens Peter Eilken · Munich, DE
• Harry Siebert · Germering, DE

Key dates

• Filing date: Sep 26, 2000
• Grant date: Sep 3, 2002
• Expiry date: Sep 26, 2020

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03L7/18
• WIPO field: Basic communication processes
• WIPO sector: Electrical engineering

Abstract

For controlling frequency and phase of an output clock signal dependent on a reference signal, a digital phase locked loop comprises a ring oscillator connected to a switch-over unit for generating the output clock signal. The ring oscillator has a plurality of serially arranged delay units. A phase comparator for comparing the phase of the reference signal and of the output clock signal. At least one switchable frequency divider unit is provided between the phase comparator and the output clock signal. A control unit controls the ring oscillator frequency by cut-in or cut-outs of delay units with the assistance of the switchover unit.