Frequency prescaler method and apparatus responsive to low input drive levels
US5939911A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 5, 1998 |
| Grant date | Aug 17, 1999 |
| Priority date | — |
| Expiry date | Mar 5, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L7/18
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A low input prescaler (800) that is responsive to input signals having low amplitude alternating current (AC) components includes a switched tunable prescaler (280) that generates a prescaler output signal (221) having a prescaler output frequency during an operational state of the prescaler and having a free-running frequency that is responsive to a tuning control signal (216) during a tuning state of the prescaler. A frequency comparator (235) generates a comparator output in response to a difference between a reference frequency and the prescaler output frequency. A prescaler tuner (290, 390) adjusts the tuning control signal in response to the comparator output during the tuning state to minimize the difference between the reference frequency and the prescaler output frequency, and holds the tuning control signal during the operational state. The prescaler is used in phase lock loops (200, 400, 600) and other circuits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.