Variable-path-length voltage-controlled oscillator circuit
US5847617A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1997 |
| Grant date | Dec 8, 1998 |
| Priority date | — |
| Expiry date | Aug 11, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K3/0315
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A variable-path-length voltage-controlled oscillator circuit is provided. The oscillator circuit has a ring oscillator formed from a series of voltage-controlled inverter stages. The path length (i.e., the number of inverter stages) in the ring is selected based on path length configuration data stored in memory. The selected path length determines the nominal or center frequency of operation of the ring oscillator. The output frequency of the oscillator circuit is voltage-tuned about this center frequency by varying the delay of each inverter stage in the ring oscillator path. Various types of voltage-controlled inverter stages may be used, including current-starved inverter stages, variable-capacitive-load inverter stages, and differential-delay inverter stages. The voltage-controlled oscillator circuit may be used in a phase-locked loop on a programmable logic device for frequency synthesis or to eliminate clock skew.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.