Fast start-up crystal oscillator
US8120439B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 13, 2009 |
| Grant date | Feb 21, 2012 |
| Priority date | — |
| Expiry date | Aug 19, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0094
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An exemplary fast start-up crystal oscillator with reduced start-up time. The exemplary oscillator reduces the start-up time (i.e., the time taken to attain sustained stable oscillations after the power is turned on) by increasing the negative resistance of a circuit. Increasing the negative resistance increases the rate of growth of the oscillations, thereby reducing start-up time. The exemplary crystal oscillator includes a gain stage with negative resistance. A crystal with shunt capacitance is placed in the feedback loop of the gain stage. A buffer is coupled to the gain stage such that it blocks the crystal shunt capacitance from loading the gain stage, effectively increasing the negative resistance of the gain stage. Further, an oscillation detection and control circuit is coupled between the crystal and the gain stage. The oscillation detection and control circuit connects the buffer during start-up, and disconnects the buffer once an oscillation signal attains sustained stable oscillations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.