Clock recovery circuit for extracting clock information from a received baseband signal

Claim 1

A clock recovery circuit, comprising: an asynchronous oscillator for generating first clock pulses at a frequency n times the frequency of a baseband signal, where n is an integer greater than unity; sampler means for sampling said baseband signal in response to said first clock pulses and producing first samples; a voltage-controlled oscillator for producing second clock pulses at a controlled frequency; latch means for holding said first samples and delivering the held first samples in response to said second clock pulses as second samples; time difference detector means for detecting a time difference between said first clock pulses and said second clock pulses; means for producing a set of tap-gain values in response to said time difference; a transversal filter for successively delaying said second samples, weighting the successively delayed second samples with said tap-gain values respectively, and producing an output signal representative of a sum of the weighted second samples; and clock phase error detector means for detecting a phase error of the output signal of said transversal filter with respect to the clock timing of the received baseband signal and controlling said voltage-controlled oscillator according to the detected clock phase error.

Claim 3

A method for recovering transmitted clock pulses from a received baseband signal, using an asynchronous oscillator which produces first clock pulses at a frequency n times the frequency of a baseband signal, where n is an integer greater than unity, and a voltage-controlled oscillator which produces second clock pulses at a controlled frequency, comprising the steps of: a) sampling said baseband signal in response to said first clock pulses and producing first samples; b) holding said first samples and delivering the held first samples in response to said second clock pulses as second samples; c) detecting a time difference between said first clock pulses and said second clock pulses; d) generating a set of tap-gain values in response to said time difference; e) successively delaying said second samples; f) respectively weighting the successively delayed second samples with the tap-gain values generated by the step (d); g) summing the weighted second samples; and h) detecting a clock phase error of the second samples summed by the step (g) with respect to the clock timing of the received baseband signal and controlling said voltage-controlled oscillator with the detected clock phase error.

Claim 4

A method for recovering transmitted clock pulses from a received baseband signal, using an asynchronous oscillator which produces first clock pulses at a frequency n times the frequency of a baseband signal, where n is an integer greater than unity, and a voltage-controlled oscillator which produces second clock pulses at a controlled frequency, comprising the steps of: a) sampling said baseband signal in response to said first clock pulses and producing first samples; b) holding said first samples and delivering the held first samples in response to said second clock pulses as second samples; c) detecting a time difference between said first clock pulses and said second clock pulses; d) generating a set of tap-gain values in response to said time difference; e) successively delaying said second samples; f) respectively weighting the successively delayed second samples with the tap-gain values generated by the step (d); g) summing the weighted second samples; and h) detecting a clock phase error of the second samples summed by the step (g) with respect to the clock timing of the received baseband signal and controlling said voltage-controlled oscillator with the detected clock phase error.