First-order loop control configuration for a phase-rotator based clock

Abstract

In an embodiment of the present invention is electronic circuitry for producing a clock signal, and its quadrature, whose phase matches the phase of input data in response to receipt of the input data and a reference clock signal, the circuitry comprises: circuitry for providing the quadrature of the reference clock signal; circuitry for providing a Q-phase quadrant pointer in response to the input data, and the reference clock; circuitry for providing an I-phase quadrant pointer in response to the input data, and the quadrature reference clock; circuitry for providing a phase signal in response to the produced clock, the quadrature of the produced clock and the input data; circuitry for providing a phase-change signal for specifying whether to rotate the phase of the produced clock signal in one direction or the other, the circuitry operable in response to the I-phase quadrant pointer, Q-phase quadrant pointer and the produced clock signal; a first phase rotator for changing the phase of the produced clock in response to the phase-change signal, the I-phase quadrant pointer, the Q-phase quadrant pointer, the reference clock, and the quadrature reference clock; and a second phase rotator for changing the phase of the quadrature of the produced clock in response to the phase-change signal, the I-phase quadrant pointer, the Q-phase quadrant pointer, the reference clock, and the quadrature reference clock.