Patent ID: 9594541
Date: 2017-03-14
CPC Classifications: G06F,H03K

Claim:
1. A device for detecting locking of a free running oscillator (FRO), comprising: a sampler configured to take periodic samples of an output of the FRO; a sample storage medium coupled to the sampler and configured to store a plurality of consecutive samples of the output of the FRO; a first pattern detector coupled with the sample storage medium, the first pattern detector being configured to, in response to a new sample being stored in the sample storage medium, detect, in the plurality of consecutive samples of the output of the FRO, repeating patterns of a first length; a second pattern detector coupled with the sample storage medium in parallel with the first pattern detector, the second pattern detector being configured to, in response to the new sample being stored in the sample storage medium, detect, in the plurality of consecutive samples of the output of the FRO, repeating patterns of a second length, the second length being different than the first length; an error counter coupled with the first pattern detector and the second pattern detector, the error counter being configured to count instances of detected repeating patterns; a threshold detector coupled to the error counter, the threshold detector being configured to output a FRO lock indication signal when the error counter reaches a preselected number of instances of detected repeating patterns, the preselected number being greater than or equal to one; and a FRO adjuster configured to adjust the FRO in response to the FRO lock indication signal.