Patent ID: 7688929

Claim:
A modulator comprising: a plurality of multi-phase clocks, each clock of multi-phase clocks having a same frequency but being offset in phase from other clocks in the plurality of multi-phase clocks; a phase rotator, coupled to the plurality of multi-phase clocks, for selecting a selected clock from the plurality of multi-phase clocks in response to a count value, and for outputting a fixed-phase clock having the same frequency as the plurality of multi-phase clocks; wherein the fixed-phase clock is a separate clock from the selected clock, wherein the fixed-phase clock and the selected clock are two different clocks; an up/down counter, responsive to an increment signal, for increasing or decreasing the count value to the phase rotator; an output divider, receiving the selected clock from the phase rotator, for generating a phase-modulated output signal that is phase-modulated in response to changes in the count value from the up/down counter; a feedback divider, receiving the fixed-phase clock from the phase rotator, for generating a feedback clock; wherein the fixed-phase clock has a phase offset that is fixed over time relative to a first clock in the plurality of multi-phase clocks; and a clocked front-end, receiving the feedback clock and an input signal, for generating the increment signal in response to changes of the input signal, wherein the feedback clock synchronizes the clocked front-end, whereby changes to the input signal cause the phase rotator to select different phase clocks from the plurality of multi-phase clocks to adjust phase of the phase-modulated output signal.