An apparatus for automatic delay calibration of a forward clock. According to the invention, the apparatus includes control logic to receive a normal clock, a lead clock and a lag clock. The control logic therefore generates a delay control signal based on a timing relationship among the normal, the lead and the lag clocks. The apparatus also includes a delay calibrator to receive a reference clock having the same frequency as the forward clock. The delay calibrator generates the lead, the phase lag and the normal clocks from the reference clock and provides them as feedback to the control logic. According to the delay control signal, the delay calibrator can adjust the lead and the lag clocks. Once the timing relationship meets a predetermined condition, the delay control signal is provided to calibrate a delay for the forward clock.