Patent ID: 8248138
Filing Date: 2012-08-21
Classification: H03K

Abstract:
1. A phase rotator, for receiving a reference clock so as to generate a digital clock signal, comprising: a delay-locked loop, for outputting a plurality of even-spaced phases according to the reference clock; a multiplexer, coupled to the delay-locked loop, for selecting two contiguous first phase and second phase selected from the even-spaced phases as its output according to a selecting signal; a phase-interpolating circuit, coupled to the multiplexer, for outputting the digital clock signal by interpolating the two contiguous first phase and second phase based upon a phase interpolating weighted value; and a state machine, coupled to the multiplexer and the phase interpolating circuit, for receiving a control signal and the two contiguous first and second phase, and controlling the multiplexer; wherein, when the control signal is enabling and the first phase or a third phase which is contiguous to the second phase is of logic high, the state machine outputs the control signal so as to change the two contiguous first and second phase to be two second phases, and then the state machine outputs the selecting signal so as to change the two contiguous first phase and second phase to be the two contiguous second and third phase.