Patent ID: 7016613

Claim:
A clock and data recovery apparatus comprising: a voltage controlled oscillator configured to provide, at a clock output, a clock signal at substantially a first frequency; a half-rate phase detector comprising a data input configured to receive a data input signal having a data rate and a data pattern, wherein the data rate is substantially twice the first frequency, the half-rate phase detector further comprising a clock input, coupled to the clock output of the voltage controlled oscillator, to receive the clock signal; the half-rate phase detector further configured to provide a first signal and a second signal, and the first signal is dependent on the phase difference between the data input signal and the clock signal and also is dependent on the data pattern, and the second signal is dependent on the data pattern but is not dependent on the phase difference; a charge pump coupled to receive the first signal and the second signal from the half-rate phase detector, wherein the charge pump combines the first signal and the second signal to generate an output signal that is dependent on the phase difference but is not dependent on the data pattern; and a low-pass filter coupled to receive the output signal from the charge pump and configured to provide a signal to the voltage controlled oscillator.