High resolution auto-tuning for a voltage controlled oscillator

摘要

According to one exemplary embodiment, an auto-tuning circuit (104) coupled to a voltage controlled oscillator (102) in a phase locked loop, where the voltage controlled oscillator is coupled to a capacitor array (105), includes a prescaler circuit (106) configured to provide a divided voltage controlled oscillator frequency, where the prescaler circuit is used in the phase locked loop during fine tuning of the voltage controlled oscillator in the auto-tuning circuit during coarse tuning of the voltage controlled oscillator. The auto-tuning circuit further includes a digital processing logic circuit (108) coupled to the prescaler circuit and configured to determine a capacitance of the capacitor array by comparing comp_cnt to a predetermined value, where comp_cnt is determined by a number of cycles of the divided voltage controlled oscillator frequency that occur in a calibration interval.