Clock circuit and method for recalibrating an injection oscillator coupled to kick-start a crystal oscillator
US10673383B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 2018 |
| Grant date | Jun 2, 2020 |
| Priority date | — |
| Expiry date | Oct 13, 2038 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2200/0094
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Embodiments of clock circuits disclosed herein include a crystal oscillator circuit, an injection oscillator coupled to kick-start the crystal oscillator circuit and a digital frequency calibration circuit coupled to recalibrate the injection oscillator. The crystal oscillator circuit is configured to generate a clock signal at a resonant frequency. The injection oscillator is coupled to supply an oscillation signal at an injection frequency to the crystal oscillator circuit to reduce a start-up time of the crystal oscillator circuit. The digital frequency calibration circuit is coupled to receive the resonant frequency and the injection frequency as inputs, and configured to supply a digital control signal to the injection oscillator to set the injection frequency of the injection oscillator substantially equal to the resonant frequency of the crystal oscillator circuit. Methods are provided herein to recalibrate the injection frequency of an injection oscillator over time, temperature and/or supply voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.