Crystal oscillator with control feedback to maintain oscillation
US6819196B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 13, 2003 |
| Grant date | Nov 16, 2004 |
| Priority date | — |
| Expiry date | Feb 13, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L5/00
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An oscillator circuit. In one embodiment, the oscillator includes a gain circuit, an envelope detector, and an amplitude comparison circuit. The trans-conductance circuit is configured to amplify a periodic signal produced by a crystal. Amplitude peaks of the periodic signal may be detected in the envelope detector, which may determine an average amplitude value based on the detected peaks. The average amplitude value may be compared to a DC voltage value in an amplitude comparison circuit. The DC voltage value may include both a DC average of the periodic signal as well as a predetermined DC offset value. The gain circuit may adjust the level of amplification of the periodic signal based on a feedback signal in order to ensure that the oscillator produces a periodic output signal at a desired level so as to insure oscillation and the minimum use of current to achieve oscillations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.