Signal delay apparatus employing a phase locked loop

Abstract

An apparatus is provided for delaying digital data signals by fixed amounts within an integrated circuit. A delay lock loop includes an adaptive delay line, a phase detector and an integrator. The integrator provides control signals c.sub.p, c.sub.n for controlling the delay line, in dependence upon the relative phase of a reference clock signal .phi..sub.0 and a delayed clock signal .phi..sub.n. The delay line includes a plurality of delay cells. By maintaining a phase relationship .phi..sub.n =.phi..sub.0 +360.degree. one clock cycle, T.sub.c, delay through the delay line is provided. Thus each delay cell provides T.sub.c /n delay. By placing identical cells in signal paths elsewhere on a chip, fixed delays can be introduced which are controlled by the delay lock loop.