an interleaved , tunable ring oscillator is disclosed that produces more output phases without resorting to interpolation . the oscillator is inherently symmetrical and suffers from none of the systematic time errors of an interpolator approach . the oscillator stages are interconnected to allow the oscillating frequency to be higher than the conventional limit of 1 /. frequency tuning is accomplished by electronically varying the delay of each stage of the ring oscillator . a mixer cell performs a weighted sum of a first input and a second delayed input . the delay ranges from the delay of the mixer itself to the sum of the delays of the mixer and the delay cell .