System for measuring delay of digital signal using clock generator and delay unit wherein a set of digital elements of clock generator identical to a set of digital elements of delay unit

摘要

A method and apparatus for a propagation delay and time calibration. The apparatus includes a ring oscillator having a first set of elements. The apparatus also includes delay units. The ring oscillator is used to generate a clock signal used to measure the delay in signals received at the delay blocks. In the depicted examples, the clock signal generated by the ring oscillator is used to run a counter that counts the delay between a transition in a data signal and a reference signal. Each of the delay units includes a second set of elements matching those of the first set of elements in the ring oscillator. The elements in the set of elements are selected such that they track the period of the ring oscillator signal generated by the ring oscillator. The delay units are used to implement the desired delay.