Digitally controlled crystal oscillator with integrated coarse and fine control
US6747522B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 2002 |
| Grant date | Jun 8, 2004 |
| Priority date | — |
| Expiry date | May 17, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03J2200/10
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method of tuning a DCXO includes the step of providing a coarse tuning array and a fine tuning array of capacitors fabricated on the same integrated circuit die. The coarse array is adjusted until the difference between a desired frequency and the output frequency corresponds to a change in capacitance no greater than half the range of the fine tuning array. In one embodiment, the fine tuning array is adjusted to mid-range before adjusting the coarse tuning array. A DCXO apparatus includes at least one integrated circuit segmented switched capacitor network providing a capacitance that is a nonmonotonic function of a composite input code. The segmented switched capacitor network includes parallel coupled binary weighted and thermometer coded switched capacitor networks for coarse and fine tuning, respectively.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.