Invention Grant
US08698566B2 Phase locked loop calibration 有权
锁相环校准

Phase locked loop calibration
Abstract:
An inductor-capacitor phase locked loop (LCPLL) includes an inductor-capacitor voltage controlled oscillator (LCVCO) that provides an output frequency. A calibration circuit includes two comparators and provides a coarse tune signal to the LCVCO. The two comparators respectively compare the loop filter signal with a first reference voltage and a second reference voltage that is higher than the first reference voltage to supply a first and second comparator output, respectively. The calibration circuit is capable of adjusting the coarse tune signal continuously in voltage values and adjusts the coarse tune signal based on the two comparator outputs. A loop filter provides a loop filter signal to the calibration circuit and a fine tune signal to the LCVCO. A coarse tune frequency range is greater than a fine tune frequency range.
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