Method and apparatus of a crystal oscillator with a noiseless and amplitude based start up control loop
US8816786B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 1, 2012 |
| Grant date | Aug 26, 2014 |
| Priority date | — |
| Expiry date | Oct 30, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03B2201/031
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A large gain is used to start up the oscillation of the crystal quickly. Once the oscillation starts, the amplitude is detected. A control circuit determines based on the measured amplitude to disable a low resistance path in the controlled switch array to reduce the applied gain below the power dissipation specification of the crystal. Another technique introduces a mixed-signal controlled power supply multi-path resistive array which tailors the maximum current to the crystal. A successive approximation register converts the amplitude into several partitions and enables/disables one of several power routing paths to the inverter of the oscillator. This allows a better match between the crystal selected by the customer and the on-chip drive circuitry to power up the oscillator without stressing the crystal. The “l/f” noise of the oscillator circuit is minimized by operating transistors in the triode region instead of the linear region.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.