Abstract: Aspects of the disclosure provide a method and an apparatus for clock and data recovery. The method and apparatus can increase jitter tolerance, and can provide recovered data with reduced jitter amplitude. The method for recovering data transmitted over a channel can include detecting a phase of a data transition within a full unit interval that includes an active zone and an inactive zone that are set based on a jitter characteristic for the channel, generating a phase directive when the phase of the data transition is located within the active zone, and adjusting a data sampling phase based on the phase directive, so that the data transmitted over the channel is sampled at a data transition edge free location.

Abstract: Aspects of the disclosure provide a method and an apparatus for clock and data recovery. The method and apparatus can increase jitter tolerance, and can provide recovered data with reduced jitter amplitude. The method for recovering data transmitted over a channel can include detecting a phase of a data transition within a full unit interval that includes an active zone and an inactive zone that are set based on a jitter characteristic for the channel, generating a phase directive when the phase of the data transition is located within the active zone, and adjusting a data sampling phase based on the phase directive, so that the data transmitted over the channel is sampled at a data transition edge free location.

Abstract: When used as a test data generator, CDR internal structures may be applied to generate drift conditions in the test data. For example, a finite state machine phase shifts a clock signal, over time, driving the test data generator thereby producing a drift condition on the test data. Once the test is completed, one of the other CDRs may be used as a tester to similarly generate test data for the first CDR. CDRs may be configured in pairs for this purpose so that one may be used to test the other.