公开(公告)号：US11139817B1

公开(公告)日：2021-10-05

申请号：US16855828

申请日：2020-04-22

Applicant: Apple Inc.

Inventor： Long Kong ,  Simone Gambini ,  Cristian Marcu ,  Nachum M. Kanovsky

IPC: H03L7/091 ,  H03L7/099 ,  H03L7/189 ,  H03L7/10

Abstract: A computer system may periodically calibrate an oscillator subsystem, which includes a voltage-controlled oscillator circuit configured to generate an oscillator signal using code signal. In response to activation of a calibration mode, an iterative calibration operation may be performed on the voltage-controlled oscillator circuit. In some cases, performing a given iteration of the calibration operation includes determining a value of the code signal using a number of pulses in the oscillator signal sampled during a particular time period, along with previous values of the code signal and a slope of an error function associated with the difference between a desired frequency and a current frequency of the oscillator signal. In other cases, iterations may employ variable sampling times with error handling, in order to decrease the duration of the calibration operation while maintaining a target accuracy.