Jitter measurement using a statistically locked loop

An apparatus for determining the jitter profile of a serial data link employing a self-clocking data signal, said apparatus comprising:

• clock recovery means coupled to receive the self-clocking data signal for generating a recovered clock signal and a recovered data signal in response to said self-clocking data signal, said recovered clock signal establishing a first time to sample said self-clocking data signal;
• programmable delay means coupled to receive the recovered clock signal for establishing a second time to sample said self-clocking data signal, the interval between said first and said second sampling times being a function of a delay value signal input to said programmable delay means;
• first circuit means operatively connected to an output of the clock recovery means and the programmable delay means for producing an induced error signal at an output indicative of a difference of results when sampling said self-clocking data signal at said first sampling time and then at said second sampling time;
• second circuit means coupled to the output of the first circuit means for producing an error ratio signal indicative of the number of said induced error signals occurring within a predetermined measurement interval;
• third circuit means including means for comparing said error ratio to a predetermined error ratio reference signal, the third circuit means producing said delay value signal in response to a difference between said error ratio signal and said predetermined error ratio reference signal;
• and
• said apparatus operating iteratively in a closed-loop manner to control said delay value signal such that said error ratio signal substantially corresponds to said predetermined error ratio reference signal.