Phase measurement and adjustment of digital signals using random sampling technique

This paper introduces a technique to measure and adjust the relative phase of on-chip high speed digital signals using a random sampling technique of inferential statistics. The proposed technique as applied to timing uncertainty mitigation in the signaling of a digital system is presented as an example; the relative phase information is used to minimize the timing skew. The proposed circuit captures the state of the signals under measurement simultaneously at random instants of time and gathers a large sample data to estimate the relative phase between the signals. By carefully premeditating the sample size, the accuracy and confidence of the result can be set to a level as high as desired. Accurately sensed value of relative phase enables the correction circuit to reduce the maximum correction error, less than half the maximum delay resolution unit available for adjustment. A pure standard cell based circuit design approach is used that reduces the overall design time and circuit complexity. The test results of the proposed circuit manifest a very close correlation to the simulated and theoretically expected results. The random sampling unit (RSU) circuit proposed for phase measurement in this paper occupies 3350 (mum)² area in 130nm technology, which is an order of magnitude smaller than what is required for its analog equivalent in the same technology