Patent ID: 7545188
Filing Date: 2009-06-09
Classification: H03D,H03K,H03L

Abstract:
1. A clock generator, comprising: a phase detector configured to generate a phase difference signal for aligning a phase of an input signal with a phase of a feedback signal, the phase difference signal representing a phase difference between the phase of the input signal and the phase of the feedback signal; a charge pump coupled to the phase detector and configured to generate a voltage signal based on the phase difference signal, the voltage signal having a voltage representing the phase difference between the phase of the input signal and the phase of the feedback signal; a low pass filter coupled to the charge pump and configured to generate a first control signal by smoothing the voltage signal; a voltage controlled oscillator coupled to the low pass filter and configured to generate a plurality of clock signals having an oscillation frequency based on the first control signal, each clock signal of the plurality of clock signals having a phase, the plurality of clock signals having a substantially constant phase relationship with each other and including at least one in-phase clock signal and at least one quadrature clock signal; and a phase shift unit coupled to the voltage controlled oscillator and the phase detector, the phase shift unit configured to select clock signals of the plurality of clock signals and to generate the feedback signal based on the selected clock signals, the phase of the feedback signal between the phases of two of the selected clock signals, the phase shift unit further configured to determine a scale factor for each of the selected clock signals for positioning the phase of the feedback signal between the phases of the selected clock signals.