Delay locked loop circuitry for generating a predetermined 
phase relationship between a pair of clocks. A first 
delay-locked loop includes a 
delay elements arranged in a chain, the chain receiving an input 
clock and generating, from each 
delay element, a set of phase vectors, each shifted a 
unit delay from the adjacent vector. The first delay-locked loop adjusts the unit delays in the delay chain using a delay adjustment 
signal so that the phase vectors span a predetermined phase shift of the input 
clock. A second delay-locked loop selects, from the first delay-locked loop, a pair of phase vectors which brackets the phase of an input 
clock. A phase interpolator receives the selected pair of vectors and generates an output clock and a delayed output clock, the amount of the delay being controlled by the delay adjustment 
signal of the first delay-locked loop circuitry. A 
phase detector compares the delayed output clock with the input clock and adjusts the phase interpolator, based on the phase comparison, so that the phase of the delayed output clock is in phase with the input clock. As a result, there is a predetermined 
phase relationship between the output clock and the input clock, the 
phase relationship being the amount of delay between the output clock and the delayed output clock. Different phase relationships between the input and output clock are possible depending on the number of unit delays used in the path of the, delayed output clock or the output clock.