Clock generators capable of generating clocks with different frequency according to a binary code. A voltage controlled oscillation module generates a plurality of first clocks (D.sub.0.about.D.sub.m) with a first frequency (f0), in which the first clocks D.sub.i and D.sub.i-1 have a fixed phase difference and 1<i<m. A logic control circuit outputs a set of corresponding clocks arranged in a corresponding sequence according to the first clocks and a binary code. A clock synthesizer generates a second clock with a second frequency (f1) according to the set of corresponding clocks, in which f1=A/B f0, A<B and A and B are positive integers.
