PROGRAMMABLE DELAY CIRCUIT WITH INTEGER AND FRACTIONAL TIME RESOLUTION

摘要

A programmable delay circuit capable of providing a delay with integer and fractional time resolution is described. In one exemplary design, an apparatus includes first and second (500) delay circuits. The first delay circuit provides a first delay of an integer number of time units. The second delay circuit (500) couples to the first delay circuit and provides a second delay of a fraction of one time unit. The first delay circuit may include multiple unit delay cells coupled in series. Each unit delay cell may provide a delay of one time unit when enabled. The second delay circuit (500) may have first and second paths. The first path may provide a shorter delay when selected, and the second path may provide a longer delay when selected. The second path may be coupled to at least one dummy logic gate (518) that provides extra loading to obtain the longer delay for the second path.