Patent ID: 7741886

Claim:
A frequency divider, comprising: a first frequency-dividing unit, for receiving an input signal, and dividing a frequency of the input signal to output a plurality of phase signals, wherein phases of the phase signals are mutually different, wherein the first frequency-dividing unit comprises: a first latch, having a trigger terminal, a non-inverting input terminal, an inverting input terminal, a non-inverting output terminal and an inverting output terminal, wherein the trigger terminal of the first latch receives the input signal; and a second latch, having a trigger terminal, a non-inverting input terminal, an inverting input terminal, a non-inverting output terminal and an inverting output terminal, wherein the trigger terminal of the second latch receives an inverted signal of the input signal, the non-inverting input terminal of the second latch is coupled to the inverting output terminal of the first latch, the inverting input terminal of the second latch is coupled to the non-inverting output terminal of the first latch, the non-inverting output terminal of the second latch is coupled to the non-inverting input terminal of the first latch, and the inverting output terminal of the second latch is coupled to the inverting input terminal of the first latch; wherein signals output from the non-inverting output terminal and the inverting output terminal of the first latch, and signals output from the non-inverting output terminal and the inverting output terminal of the second latch are the phase signals; a selecting unit, coupled to the first frequency-dividing unit, for selecting one of the phase signals according to a control signal to output an inner signal; a second frequency-dividing unit, coupled to the selecting unit, for dividing the frequency of the inner signal to serve as an output signal; and a counting unit, coupled to the selecting unit, for counting the inner signal and outputting a counting result as the control signal.